Chapter 28: Fractures of the Distal Femoral Physis

Martin J. Herman, Brian G. Smith

Chapter Outline

Introduction to Fractures of the Distal Femoral Physis

Distal femoral physeal injuries are uncommon, accounting for fewer than 2% of all physeal injuries.40,52,65 However, complications requiring additional surgery occur after approximately 40% to 60% of these injuries.2,24,29,37,50,71,82,83 The most common complication is growth disturbance of the distal femur resulting in angular deformity and/or shortening. In one meta-analysis of the published literature from 1950 to 2007 that included 564 fractures, 52% of fractures resulted in a growth disturbance.7 This complication has been reported in patients of all ages regardless of the mechanism of injury, type of fracture, anatomic reduction of the fracture, and the type of treatment.2,24,29,37,50,82,83 In addition to growth complications, knee stiffness, ligamentous disruption, neurovascular injuries, and compartment syndrome may occur as a result of these injuries.24,29,71,80,83 Although the prognosis is better for very young children and nondisplaced fractures, complications may occur after any distal femoral physeal injury. Careful clinical assessment, complete diagnostic imaging, anatomic reduction, and secure immobilization or fixation to maintain reduction are necessary to ensure the best possible outcomes. Close follow-up at regular 6-month intervals after fracture healing until skeletal maturity is recommended to allow for early detection and treatment of clinically significant growth disturbances. 

Assessment of Fractures of the Distal Femoral Physis

Mechanisms of Injury of Fractures of the Distal Femoral Physis

Prior to the advent of radiography, this injury was termed the “wagon-wheel injury” or “cartwheel injury” because it occurred when a child attempted to jump onto or fell from a moving wagon and the leg became entrapped between the spokes of the moving wheel. Because adequate methods of evaluation and orthopedic management had not yet been developed, this injury often led to amputation frequently because of associated neurovascular trauma.36 Today, most distal femoral physeal fractures are the result of high-energy mechanisms, such as motor vehicle or sports-related trauma, and occur in older children and adolescents. Children between the ages of 2 and 11 years are less likely to sustain these fractures compared to adolescents, or even infants.71 

Infants and Toddlers

Neonates are susceptible to distal femoral physeal fractures from birth trauma. Factors that predispose the newborn to this injury include breech presentation, macrosomia, difficult vaginal delivery, and rapid labor and delivery.42 This injury has been also reported after delivery by caesarean section.38 Child abuse should be suspected in infants and toddlers when a small peripheral metaphyseal fragment of bone, also called a “corner fracture,” or the “classic metaphyseal lesion,” is identified in association with widening of the distal femoral physis on radiographs of the femur or knee (Fig. 28-1).48 This radiographic finding is pathognomonic for child abuse. If this radiographic sign is identified, regardless of the reported mechanism of injury, the child should be carefully examined for other signs of mistreatment; a skeletal survey is obtained to identify other skeletal injuries and an immediate referral to your institution's child protection team and local child welfare services must be initiated. 
Figure 28-1
Lateral radiograph of a swollen knee in a 3-month-old girl who reportedly fell out of her crib 8 days earlier.
 
Subperiosteal ossification along the distal femoral shaft indicates separation of the distal femoral epiphysis. Note evidence of fracture separation of the proximal tibial epiphysis as well. Final diagnosis: Abused child.
Subperiosteal ossification along the distal femoral shaft indicates separation of the distal femoral epiphysis. Note evidence of fracture separation of the proximal tibial epiphysis as well. Final diagnosis: Abused child.
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Figure 28-1
Lateral radiograph of a swollen knee in a 3-month-old girl who reportedly fell out of her crib 8 days earlier.
Subperiosteal ossification along the distal femoral shaft indicates separation of the distal femoral epiphysis. Note evidence of fracture separation of the proximal tibial epiphysis as well. Final diagnosis: Abused child.
Subperiosteal ossification along the distal femoral shaft indicates separation of the distal femoral epiphysis. Note evidence of fracture separation of the proximal tibial epiphysis as well. Final diagnosis: Abused child.
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Pathologic Fractures

Underlying conditions such as neuromuscular disorders, joint contractures, or nutritional deficiencies may predispose some children, regardless of age, for separation of the distal femoral epiphysis.35,51,63 Like other pathologic fractures, distal femoral physeal separations that occur in children with underlying conditions typically result from low-energy mechanisms, such as inadvertent twisting of the limb during transferring from a bed or stretching during physical therapy. Nonambulatory children, such as children with cerebral palsy, are particularly susceptible to pathologic fractures due to disuse osteopenia. Ambulatory children with spina bifida may develop epiphysiolysis, or a chronic separation of the distal femoral physis, and be unaware of it because of altered sensation. Salter–Harris fractures of the distal femur have been reported during manipulation of the knee under anesthesia in children who had developed knee contractures secondary to arthrofibrosis after treatment of displaced tibial eminence fractures.86 

Biomeachanics of the Injury of Fractures of the Distal Femoral Physis

In the adolescent with open growth plates about the knee, the most common mechanism of fracture of the distal femoral physis is a varus or valgus stress (Fig. 28-2) across the knee joint from a direct blow or buckling while landing from a jump or fall from a height. In most cases, this medially or laterally directed force is coupled with a torsional moment from direct application of force to the foot, or more commonly, from twisting of the knee on the planted foot. In an animal model, the physis is least able to resist torsional forces.15 Knee hyperextension or hyperflexion forces result in sagittal plane displacement. The combination of forces applied to the physis, however, determines the direction of displacement of the distal fragment. 
Figure 28-2
Valgus and torsional stress across the knee may cause a ligament injury or physeal separation.
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Loading the limb to failure across the immature knee is more likely to lead to physeal disruption due to tensile stresses that are transmitted through the ligaments to the adjacent physis than it is to disruption of the major knee ligaments.25 Varus or valgus forces (Fig. 28-3A) create tension on one side of the physis and compression on the opposite side. The result is the disruption of the periosteum, which may become entrapped between the epiphysis and the metaphysis, and the perichondrial ring on the tension side, followed by a fracture plane that begins in the hypertrophic zone and proceeds in an irregular manner through the physis.15 In adults, a similar mechanism of injury is more likely to cause ligamentous disruption rather than bone failure because ligaments of the mature knee are less able to withstand extreme tensile forces compared to the bone of the adult distal femur and proximal tibia (Fig. 28-3B). 
Figure 28-3
 
A: In a skeletally immature patient, valgus force at the knee is more likely to cause a physeal fracture of the distal femur than a medial collateral ligament tear, an injury that occurs in adults. B: With correction of the valgus deformity, periosteum may become entrapped.
 
(Reprinted with permission from Skaggs DL, Flynn JF. Trauma about the knee, tibia, and foot. In: Skaggs DL, Flynn JF, eds. Staying Out of Trouble in Pediatric Orthopaedics. Philadelphia, PA: Lippincott Williams & Wilkins; 2006.)
A: In a skeletally immature patient, valgus force at the knee is more likely to cause a physeal fracture of the distal femur than a medial collateral ligament tear, an injury that occurs in adults. B: With correction of the valgus deformity, periosteum may become entrapped.
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Figure 28-3
A: In a skeletally immature patient, valgus force at the knee is more likely to cause a physeal fracture of the distal femur than a medial collateral ligament tear, an injury that occurs in adults. B: With correction of the valgus deformity, periosteum may become entrapped.
(Reprinted with permission from Skaggs DL, Flynn JF. Trauma about the knee, tibia, and foot. In: Skaggs DL, Flynn JF, eds. Staying Out of Trouble in Pediatric Orthopaedics. Philadelphia, PA: Lippincott Williams & Wilkins; 2006.)
A: In a skeletally immature patient, valgus force at the knee is more likely to cause a physeal fracture of the distal femur than a medial collateral ligament tear, an injury that occurs in adults. B: With correction of the valgus deformity, periosteum may become entrapped.
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Associated Injuries with Fractures of the Distal Femoral Physis

Because many of these injuries are the result of high-energy mechanisms such as traffic accidents and motor sports, associated visceral injuries occur in approximately 5% of patients.24 Other musculoskeletal injuries are seen in association with distal femoral physeal fractures in 10% to 15% of patients.24,83 Other long bone fractures, as well as pelvic and spine fractures, must be ruled out, especially if the mechanism of injury is high-energy motor trauma (Fig. 28-4). Knee ligament disruption, however, is the most common concomitant musculoskeletal injury. Knee instability is diagnosed in 8% to 37% of patients11,24 and is typically diagnosed after fracture healing with the initiation of rehabilitation and return to activities. Salter–Harris type III fractures of the medial femoral condyle are most frequently associated with anterior cruciate ligament injuries.16,54,68,85 Open fractures and vascular injuries are uncommon associated injuries, occurring in about 3% of patients. Peroneal nerve injury occurs in about 2% to 7% of patients with displaced fractures.10,24 
Figure 28-4
A 7-year-old girl struck by a car sustained this closed injury while crossing the street.
 
Radiographs (A, AP and B, lat) reveal an anteriorly displaced distal femoral physeal separation and a tibial shaft fracture. Upon admission she had no pulse in the extremity. She underwent emergency open reduction and fixation of the distal femur and IM nail fixation of the tibia (C–E). Her pulses returned to normal after femur reduction. She did not develop a compartment syndrome.
Radiographs (A, AP and B, lat) reveal an anteriorly displaced distal femoral physeal separation and a tibial shaft fracture. Upon admission she had no pulse in the extremity. She underwent emergency open reduction and fixation of the distal femur and IM nail fixation of the tibia (C–E). Her pulses returned to normal after femur reduction. She did not develop a compartment syndrome.
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Figure 28-4
A 7-year-old girl struck by a car sustained this closed injury while crossing the street.
Radiographs (A, AP and B, lat) reveal an anteriorly displaced distal femoral physeal separation and a tibial shaft fracture. Upon admission she had no pulse in the extremity. She underwent emergency open reduction and fixation of the distal femur and IM nail fixation of the tibia (C–E). Her pulses returned to normal after femur reduction. She did not develop a compartment syndrome.
Radiographs (A, AP and B, lat) reveal an anteriorly displaced distal femoral physeal separation and a tibial shaft fracture. Upon admission she had no pulse in the extremity. She underwent emergency open reduction and fixation of the distal femur and IM nail fixation of the tibia (C–E). Her pulses returned to normal after femur reduction. She did not develop a compartment syndrome.
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Signs and Symptoms of Fractures of the Distal Femoral Physis

Presentation

Emergency department assessment for children who are victims of high-energy trauma with a suspected distal femoral physeal separation should be initially evaluated by the trauma team to identify potential life-threatening injuries, to evaluate the ABCs, and to initiate resuscitation protocols if indicated. On the initial survey, head trauma, thoracoabdominal injuries, unstable spine and pelvic fractures, and limb-threatening extremity injuries are the priorities. After stabilization of the cardiovascular status, a thorough secondary survey should focus on the extremities. Long-bone fractures and ligamentous injuries of the extremities are identified with a careful orthopedic examination of all four extremities. Although severe injuries may occur in association with fractures of the distal femoral physis, this fracture, however, occurs as an isolated injury in most patients. 
For patients with displaced distal femoral physeal fractures, the diagnosis may be obvious. Patients typically describe severe pain, giving way of the limb and obvious knee deformity after a sports injury, motor vehicle accident, or other high-energy mechanism and are unable to walk or bear weight on the injured limb. On examination, visible limb malalignment, severe swelling, and often ecchymosis at the apex of the knee deformity are identified. In fractures with severe displacement, the skin at the apex may be tented or puckered from protrusion of the metaphyseal distal femur through the periosteum and quadriceps muscle into the dermis. Hematoma may be palpable beneath the skin. Abrasions or laceration of the overlying soft tissues may be a clue to the mechanism of injury or to an open fracture (Fig. 28-5). Assessment of knee range of motion and ligament stability is not possible in most cases with obvious displacement because of pain and the poor reliability of the examination in the face of fracture instability. Aggressive manipulation is also potentially harmful to the fractured physis or neurovascular structures that are already compromised. 
Figure 28-5
 
A: Completely displaced Salter–Harris type II fracture of the distal femur in a 6-year-old girl whose foot was on the back of the driver's headrest when the automobile in which she was riding was involved in an accident. B: Ecchymosis in the popliteal fossa and anterior displacement of the distal femur are evident. Clinical examination revealed absence of peroneal nerve function and a cold, pulseless foot. The fracture was irreducible by closed methods and required open reduction, internal fixation, and repair of a popliteal artery laceration. C, D: Follow-up x-rays show excellent healing after pin removal. The reduction had been incomplete with 25 degrees of posterior angulation remaining. E, F: Four years later, remodeling has occurred and no growth disturbance is noted. Results such as this cannot be relied upon, and early anatomic reduction is recommended.
A: Completely displaced Salter–Harris type II fracture of the distal femur in a 6-year-old girl whose foot was on the back of the driver's headrest when the automobile in which she was riding was involved in an accident. B: Ecchymosis in the popliteal fossa and anterior displacement of the distal femur are evident. Clinical examination revealed absence of peroneal nerve function and a cold, pulseless foot. The fracture was irreducible by closed methods and required open reduction, internal fixation, and repair of a popliteal artery laceration. C, D: Follow-up x-rays show excellent healing after pin removal. The reduction had been incomplete with 25 degrees of posterior angulation remaining. E, F: Four years later, remodeling has occurred and no growth disturbance is noted. Results such as this cannot be relied upon, and early anatomic reduction is recommended.
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A: Completely displaced Salter–Harris type II fracture of the distal femur in a 6-year-old girl whose foot was on the back of the driver's headrest when the automobile in which she was riding was involved in an accident. B: Ecchymosis in the popliteal fossa and anterior displacement of the distal femur are evident. Clinical examination revealed absence of peroneal nerve function and a cold, pulseless foot. The fracture was irreducible by closed methods and required open reduction, internal fixation, and repair of a popliteal artery laceration. C, D: Follow-up x-rays show excellent healing after pin removal. The reduction had been incomplete with 25 degrees of posterior angulation remaining. E, F: Four years later, remodeling has occurred and no growth disturbance is noted. Results such as this cannot be relied upon, and early anatomic reduction is recommended.
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Figure 28-5
A: Completely displaced Salter–Harris type II fracture of the distal femur in a 6-year-old girl whose foot was on the back of the driver's headrest when the automobile in which she was riding was involved in an accident. B: Ecchymosis in the popliteal fossa and anterior displacement of the distal femur are evident. Clinical examination revealed absence of peroneal nerve function and a cold, pulseless foot. The fracture was irreducible by closed methods and required open reduction, internal fixation, and repair of a popliteal artery laceration. C, D: Follow-up x-rays show excellent healing after pin removal. The reduction had been incomplete with 25 degrees of posterior angulation remaining. E, F: Four years later, remodeling has occurred and no growth disturbance is noted. Results such as this cannot be relied upon, and early anatomic reduction is recommended.
A: Completely displaced Salter–Harris type II fracture of the distal femur in a 6-year-old girl whose foot was on the back of the driver's headrest when the automobile in which she was riding was involved in an accident. B: Ecchymosis in the popliteal fossa and anterior displacement of the distal femur are evident. Clinical examination revealed absence of peroneal nerve function and a cold, pulseless foot. The fracture was irreducible by closed methods and required open reduction, internal fixation, and repair of a popliteal artery laceration. C, D: Follow-up x-rays show excellent healing after pin removal. The reduction had been incomplete with 25 degrees of posterior angulation remaining. E, F: Four years later, remodeling has occurred and no growth disturbance is noted. Results such as this cannot be relied upon, and early anatomic reduction is recommended.
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A: Completely displaced Salter–Harris type II fracture of the distal femur in a 6-year-old girl whose foot was on the back of the driver's headrest when the automobile in which she was riding was involved in an accident. B: Ecchymosis in the popliteal fossa and anterior displacement of the distal femur are evident. Clinical examination revealed absence of peroneal nerve function and a cold, pulseless foot. The fracture was irreducible by closed methods and required open reduction, internal fixation, and repair of a popliteal artery laceration. C, D: Follow-up x-rays show excellent healing after pin removal. The reduction had been incomplete with 25 degrees of posterior angulation remaining. E, F: Four years later, remodeling has occurred and no growth disturbance is noted. Results such as this cannot be relied upon, and early anatomic reduction is recommended.
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Patients with nondisplaced fractures are more difficult to diagnose. Many children with nondisplaced distal femoral physeal fractures present with knee pain or mild knee swelling after a twisting injury or blow to the knee but are able to bear weight, albeit with often a painful limp. Point tenderness at the level of the distal femoral physis, either medially or laterally about the knee, is perhaps the most reliable way to detect this injury. Range of motion is typically painful but may not be severely restricted in all cases, and fracture crepitus is absent because the periosteum is not fully disrupted. Varus/valgus stress testing of the knee ligaments is usually painful and, in some cases, may reveal subtle movement or suggest instability. The examiner, however, must be mindful that a skeletally immature patient with point tenderness at the physis is more likely to have sustained a physeal fracture of the distal femur, compared to disruption of the medial or lateral collateral ligaments of the knee. Therefore, forceful or repeated stress testing of the knee in these cases should be avoided to minimize trauma to the injured physis. 

Motor and Sensory Testing

Careful neurovascular examination of the lower leg and foot must be performed for all children with suspected fractures of the distal femoral physis, especially for those with obvious limb deformity. Complete motor and sensory testing of the distal limb is necessary to identify injury of the sciatic nerve and its branches, the tibial and common peroneal nerves. Because the peroneal nerve is injured in about 2% of patients with displaced fractures10 and is the most commonly injured nerve related to this fracture,24 it is especially important that anterior (deep branch) and lateral (superficial branch) compartment muscle function and lower leg sensation be carefully documented. This nerve injury is typically a neurapraxia, the result of stretching from anterior or medial displacement of the distal femoral epiphysis. 

Vascular Assessment

Although vascular injuries are rare after fractures of the distal femoral physis,24,50,71,83 the vascular status must also be evaluated carefully. The distal pulses are palpated in the foot and ankle and other signs of adequate perfusion are evaluated. These other signs include assessment of capillary refill, skin temperature, and signs of venous insufficiency such as distal swelling or cyanosis. Doppler ultrasound and measurement of ankle-brachial indices are methods available in the emergency department which are useful for detecting less obvious vascular injury when pulses and other signs are equivocal. Laceration, intimal tear, and thrombosis in the popliteal artery may occur by direct injury to the artery by the distal end of the metaphysis when the epiphysis is displaced anteriorly during a hyperextension injury.10,24,74 Because anteriorly displaced fractures have an increased risk of neurovascular damage in general compared to other directions of displacement,21,80 the patient must be particularly suspicious for a vascular injury with obvious hyperextension deformity of the knee. 
Compartment syndrome after distal femoral physeal fracture is rare but in one series occurred in 1.2% of patients.24 Signs of compartment syndrome in the lower leg such as severe swelling, tenseness or tenderness of compartments, and examination abnormalities consistent with the diagnosis are also evaluated. Compartmental pressure recordings should be obtained if there are clinical findings of compartment syndrome of the lower leg. Compartment syndrome in association with this fracture is more likely to manifest hours after injury; however, not at the time of initial presentation. Patients at risk for developing a delayed compartment syndrome after fracture are those with other injuries of the lower leg, such as tibial shaft fractures, and those with compromised vascularity.24 

Imaging and Other Diagnostic Studies for Fractures of the Distal Femoral Physis

Radiographs

High-quality orthogonal radiographic views of the femur and knee are for diagnosing distal femoral physeal separations (Table 28-1). On the AP radiographic, physeal widening and the presence of a fracture line proximally in the metaphysis or distally in the epiphysis allows the surgeon to differentiate between the four most common Salter–Harris types, i.e., types 1 to 4. In addition, epiphyseal varus (also called apex lateral angulation) or valgus (also called apex medial angulation) and medial or lateral translation in the coronal plane are determined on the AP view. The lateral projection defines the amount of angulation and translation of the epiphysis in the sagittal plane. The anteriorly displaced epiphysis is usually tilted so that the distal articular surface faces anteriorly. This direction of displacement is alternatively called hyperextension of the epiphysis or apex posterior angulation. The posteriorly displaced epiphysis is tilted downward so that the distal articular surface faces the popliteal fossa, sometimes described as hyperflexion of the epiphysis or apex anterior angulation. Minor degrees of displacement may be difficult to measure on plain films unless the x-ray projection is precisely in line with the plane of fracture. Even small amounts of displacement are significant.37,50 Rotational malalignment of the distal fragment relative to the proximal fragment may be identified on either view and is dramatic in some cases with severe displacement. 
Table 28-1
Imaging Studies in the Evaluation of Distal Femoral Physeal Fractures
Study Indications Limitations
Standard radiographs First study, often sufficient May miss nondisplaced Salter–Harris type I or III fractures or underestimate fracture displacement
CT scan Best defines fracture pattern and amount of displacement Poor cartilage visualization. Increased radiation exposure
Useful for planning surgery, especially for metaphyseal comminution Less useful than MRI in evaluating for occult Salter–Harris type I or III fractures
MRI Evaluation of occult Salter–Harris type I fracture, especially in infants with little epiphyseal ossification Availability, cost, duration of procedure
Identifies associated soft tissue injuries, especially with Salter–Harris type III fractures Fracture geometry less clear than with CT scans
Stress views Differentiate occult Salter–Harris fracture from ligament injury Painful, muscle spasm may not permit opening of fracture if patient awake. Potentially harmful to physis
Contralateral radiographs Infants, or to assess physeal width Usually not helpful in acute fractures
Follow-up to compare growth
Ultrasonography
Arthrography
Infants to assess swelling and displacement of epiphysis Not useful after infancy
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Diagnosis of minimally displaced distal femoral physeal fractures is challenging. Because the physis normally is radiolucent, injury is typically identified because of physeal widening, epiphyseal displacement, or metaphyseal bone injury suggestive of a fracture. Without obvious radiographic abnormalities, nondisplaced Salter–Harris type I or III fracture without separation can be easily overlooked.5,72,85 Oblique views of the distal femur may reveal an occult fracture through the epiphysis or metaphysis. In the past, stress views of the distal femur were recommended for patients with negative radiographs who have an effusion or tenderness localized to the physis.78 However, it is our practice to forego stress radiographs because they are painful to the patient and may damage the already compromised physis. Presumptive S-H I fractures are then either immobilized for 1 to 2 weeks and reexamined or are further evaluated with MRI.54,78,81,85 

MRI

MRI is the most commonly used advanced imaging study for evaluating traumatic knee injuries in children and adolescents. The primary utility of MRI is to identify acute knee injuries when the examination and radiographs are nondiagnostic or to confirm diagnostic suspicions. In one large MRI study of 315 adolescents with acute traumatic knee injuries, physeal injuries of the distal femur were diagnosed in seven patients with negative plain radiographs.19 MRI also facilitates identification of knee ligament tears, meniscal pathology, and osteochondral fractures that may occur concomitantly with distal femoral physeal fractures,54 both in the acute setting and after fracture healing. MR arteriography is one method of evaluating vascular anatomy and flow in patients with an abnormal vascular examination in association with displaced distal femoral physeal fractures. 

CT Scan

Computed tomography (CT) scan is recommended for all patients with Salter–Harris III and IV fractures diagnosed on plain radiographs. In one study, CT identified fracture displacement and comminution that was not recognized on plain radiographs of the knee. The authors encouraged its use for evaluation of these fractures to identify displacement, define fracture geometry, and plan surgical fixation.46 CT may also be useful to identify fractures and displacement in cases where the plain radiographs are negative but the examination is suspicious for a distal femoral physeal fracture. 

Special Situations of Fractures of the Distal Femoral Physis

Neonate

Separation of the distal femoral epiphysis in a neonate is particularly difficult to diagnose on initial X-rays unless there is displacement, because only the center of the epiphysis is ossified at birth. This ossification center is in line with the axis of the femoral shaft on both AP and lateral views in normal infants. Any degree of malalignment of the ossification center from the shaft should raise suspicion for this fracture. Comparison views of the opposite knee and other modalities may also be helpful to identify its presence in neonates when radiographs of the affected leg are equivocal. MRI, performed under anesthesia, is another commonly used diagnostic imaging study that may help to identify a separation of the unossified femoral epiphysis.88 
Unique to the neonate is the use of ultrasonography35 to evaluate distal femoral physeal separation. Typically used to evaluate the immature hip for developmental dysplasia of the hip, diagnostic ultrasound imaging may also be used to evaluate the cartilaginous distal femur in a young child with incomplete ossification of the distal femoral epiphysis. Although this study is safe and readily available, it is unfamiliar to many technicians and radiologists, making its reliability questionable unless performed by an experienced team. This modality may be used not only to diagnose injuries but also to guide reduction. Knee arthrography, another option for evaluating the immature distal femoral epiphysis for possible disruption, is primarily used to facilitate reduction and fixation in the operating room. 

Physeal Arrest

The best method for determining the viability of the physis after healing of a traumatic injury is MRI performed with fat-suppressed three-dimensional spoiled gradient-recalled echo sequences.22 Impending growth disturbance can be identified early with this MRI22,26 technique and MRI can be used to map the extent of physeal bony bar formation to determine if excision is an option for treatment.22,49 Although CT may also be used to map the location and area of physeal bars, it is out preference to use MRI because it does not expose the child to radiation and evaluates the quality of the physeal cartilage adjacent to the bar, a possible predictor of the success of physeal excision. 

Classifications of Fractures of the Distal Femoral Physis

Salter–Harris Classification

Several types of classification schemes have been used to describe fractures of the distal femoral physis, each with some merit because of the information that its use provides to the surgeon. The Salter–Harris classification74 is the most widely used classification scheme (Fig. 28-6). This familiar classification system, based on plain radiographs, is useful for the description of the types of physeal fractures of the distal femur. As opposed to its application to other physeal fractures, however, the Salter–Harris scheme is not as reliable in predicting the risk of growth disturbance as it relates to the fracture types.24,50 For many physeal fractures in other anatomic sites, risk of growth disturbance is smaller after type I and II fractures and higher after types III and IV. Distal femoral physeal fractures, however, are at risk for significant growth disturbance regardless of type.7,50,82 This classification scheme is useful for treatment planning and is also a good indicator of the mechanism of injury.21 
Figure 28-6
The Salter–Harris classification of fractures involving the distal femoral physis.
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Salter–Harris I Fractures.
The Salter–Harris type I pattern is a fracture that traverses the distal femoral physis, without extension either proximally into the metaphysis or distally into the epiphysis or knee joint (Fig. 28-7). Anatomically, this fracture cleaves the physis predominately across the physeal zones of cell hypertrophy and provisional calcification. Because of the undulation of the distal femoral physis, likely evolutionarily developed to increase the stability of the physeal plate when subject to shear stress, most distal femoral physeal fractures do not propagate cleanly across these zones but instead also extend into the germinal zones of the physis. This encroachment of the fracture line into cartilage precursor cells is likely the explanation for increased rates of growth disturbance after S-H I and S-H II fracture types. 
Figure 28-7
 
A: Salter–Harris type I fracture of the distal femur in an 8-year old. B: Lateral view shows hyperextension. C: Fixation following closed reduction under general anesthesia. Note that pins are widely separated at the fracture site. D: Lateral view of fixation.
A: Salter–Harris type I fracture of the distal femur in an 8-year old. B: Lateral view shows hyperextension. C: Fixation following closed reduction under general anesthesia. Note that pins are widely separated at the fracture site. D: Lateral view of fixation.
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Figure 28-7
A: Salter–Harris type I fracture of the distal femur in an 8-year old. B: Lateral view shows hyperextension. C: Fixation following closed reduction under general anesthesia. Note that pins are widely separated at the fracture site. D: Lateral view of fixation.
A: Salter–Harris type I fracture of the distal femur in an 8-year old. B: Lateral view shows hyperextension. C: Fixation following closed reduction under general anesthesia. Note that pins are widely separated at the fracture site. D: Lateral view of fixation.
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Although this fracture pattern may be seen in any age group of skeletally immature patients, it occurs more frequently in infants, the result of birth trauma or abuse, and in adolescents with sports-related trauma. Many S-H I fractures are nondisplaced and may go undetected. Sometimes, the diagnosis is made only in retrospect, after subperiosteal new bone formation occurs along the adjacent metaphysis, evident on follow-up radiographs 10 to 14 days after injury or by MRI. When displacement is present before the age of 2 years, it usually occurs in the sagittal plane. Approximately 15% of physeal fractures of the distal femur are type I fractures.7 
Salter–Harris II Fractures.
The Salter–Harris type II pattern is the most common type of separation of the distal femoral epiphysis (Fig. 28-8). This pattern is characterized by a fracture line that extends through the physis incompletely and then exits proximally via an oblique extension of the fracture line through the metaphysis. The metaphyseal corner that remains attached to the epiphysis is called the Thurston Holland fragment. Although the direction of displacement varies, typically the direction of displacement is also the location of the metaphyseal fragment because the metaphyseal spike occurs on the side of compression forces. This fracture type may also be seen in children of all ages but is more common in adolescents. Slightly more than half (57%) of all distal femoral physeal fractures are S-H II fractures.7 
Figure 28-8
 
A: Salter–Harris type II fracture in a 12-year-old boy. B: Lateral view. C: AP view after closed reduction and fixation. Note that screws function in compression with threads across fracture line. D: Lateral view. E: Six months after injury, this plain radiograph was suspicious of increased valgus. Note that the radiograph is not centered on the distal physis, and thus the physis is difficult to visualize.
A: Salter–Harris type II fracture in a 12-year-old boy. B: Lateral view. C: AP view after closed reduction and fixation. Note that screws function in compression with threads across fracture line. D: Lateral view. E: Six months after injury, this plain radiograph was suspicious of increased valgus. Note that the radiograph is not centered on the distal physis, and thus the physis is difficult to visualize.
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Figure 28-8
A: Salter–Harris type II fracture in a 12-year-old boy. B: Lateral view. C: AP view after closed reduction and fixation. Note that screws function in compression with threads across fracture line. D: Lateral view. E: Six months after injury, this plain radiograph was suspicious of increased valgus. Note that the radiograph is not centered on the distal physis, and thus the physis is difficult to visualize.
A: Salter–Harris type II fracture in a 12-year-old boy. B: Lateral view. C: AP view after closed reduction and fixation. Note that screws function in compression with threads across fracture line. D: Lateral view. E: Six months after injury, this plain radiograph was suspicious of increased valgus. Note that the radiograph is not centered on the distal physis, and thus the physis is difficult to visualize.
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Salter–Harris III Fractures.
The Salter–Harris type III injury has a fracture line that traverses part of the physis then exits distally, with extension of the fracture line vertically across the physis, epiphysis, and its articular surface (Fig. 28-9). Most Salter–Harris type III injuries of the distal femur traverse the medial physis and extend into the joint, separating the medial condyle from the lateral condyle of the distal femur. These injuries are often produced by valgus stress across the knee, the same mechanism of injury that produces medial collateral and cruciate ligament disruption in skeletally mature patients may have an associated injury to the cruciate ligaments.16,66 This fracture occurs most frequently in older children and adolescents and comprises about 10% of all distal femoral physeal fractures.7 
Figure 28-9
 
A: Salter–Harris type III fracture separation of the distal femur. Note the vertical fracture line extending from the physis distally into the intercondylar notch with displacement. B: After reduction and fixation with two compression screws extending transversely across the epiphyseal fragments. Note closure and healing of the vertical fracture line in the epiphysis, with restoration of the articular surface.
A: Salter–Harris type III fracture separation of the distal femur. Note the vertical fracture line extending from the physis distally into the intercondylar notch with displacement. B: After reduction and fixation with two compression screws extending transversely across the epiphyseal fragments. Note closure and healing of the vertical fracture line in the epiphysis, with restoration of the articular surface.
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Figure 28-9
A: Salter–Harris type III fracture separation of the distal femur. Note the vertical fracture line extending from the physis distally into the intercondylar notch with displacement. B: After reduction and fixation with two compression screws extending transversely across the epiphyseal fragments. Note closure and healing of the vertical fracture line in the epiphysis, with restoration of the articular surface.
A: Salter–Harris type III fracture separation of the distal femur. Note the vertical fracture line extending from the physis distally into the intercondylar notch with displacement. B: After reduction and fixation with two compression screws extending transversely across the epiphyseal fragments. Note closure and healing of the vertical fracture line in the epiphysis, with restoration of the articular surface.
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Nondisplaced S-H III and IV fractures and other more complex patterns of distal femoral physeal fracture may not always be detectable or fully delineated on plain radiographs, requiring MRI or CT to identify.45,53,54,58 It has been hypothesized that the Salter–Harris type III fracture, seen mostly in older children and adolescents, may occur as a consequence of the progression of closure of the distal femoral physis. This pattern of fracture occurs near skeletal maturity when the central portion of the distal femoral physis begins to close before the medial and lateral parts of the physis, similar to a juvenile Tillaux fracture of the distal tibia.54 Occasionally, a type III fracture may occur in the coronal plane of the distal femoral condyle, more commonly the medial femoral condyle, similar to the “Hoffa fracture” of the posterior condyle seen in adults.45,58 This fracture is difficult to diagnose with standard x-rays72 and is also challenging to reduce and fix. A triplane fracture of the distal femur, a fracture that appears as an S-H I injury in the sagittal plane and an S-H III fracture in the coronal and sagittal planes, has also been described.53 This triplane fracture is not completely analogous to the classic triplane fracture of the ankle, however, because, while the fracture line extends in three dimensions about the physis, the distal femoral physis is completely open. 
Salter–Harris IV Fractures.
In Salter–Harris type IV injuries of the distal femur, the fracture line extends vertically through the metaphysis, across the physis, ultimately extending through the epiphysis and its articular surface (Fig. 28-10). It is at times difficult to distinguish between S-H III and S-H IV fractures because the metaphyseal fragment may be small and difficult to identify on plain radiographs. S-H III and IV fractures likely occur from similar mechanisms and in the same age ranges, with both presenting management challenges that require anatomic realignment of the joint line and physis to minimize risk of growth disturbance. Of fractures of the distal femoral physis, this fracture type is seen slightly more frequently than type III fractures, accounting for about 12% of fractures.7 
Figure 28-10
 
A: Comminuted Salter–Harris type IV fracture of the distal femur in a 14-year-old boy involved in a motor vehicle accident. B: Six months after open reduction and internal fixation with cannulated screws in the metaphysis and epiphysis.
A: Comminuted Salter–Harris type IV fracture of the distal femur in a 14-year-old boy involved in a motor vehicle accident. B: Six months after open reduction and internal fixation with cannulated screws in the metaphysis and epiphysis.
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Figure 28-10
A: Comminuted Salter–Harris type IV fracture of the distal femur in a 14-year-old boy involved in a motor vehicle accident. B: Six months after open reduction and internal fixation with cannulated screws in the metaphysis and epiphysis.
A: Comminuted Salter–Harris type IV fracture of the distal femur in a 14-year-old boy involved in a motor vehicle accident. B: Six months after open reduction and internal fixation with cannulated screws in the metaphysis and epiphysis.
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Salter–Harris V Fractures.
When initial radiographs of the distal femur are normal but subsequent imaging months after the traumatic injury identify a growth arrest, this fracture is termed a Salter–Harris V.79 It is hypothesized that compression forces across the physis causes damage to the cartilage-producing cells in the growth plate but no epiphyseal displacement. Axial loading of the limb, such as from a fall from a height, is considered the classic mechanism of injury. It important to bear in mind, however, that premature growth arrest also may occur in association with nonphyseal fractures of the femoral and tibial shafts.8,33,57,76 MRI may identify bone contusion on both sides of the growth plate after a traumatic injury that may be a harbinger to its occurrence.76 Approximately 3% of physeal separations of the distal femur are Salter–Harris V fractures. 
Salter–Harris VI.
Rang59,70 proposed a sixth type of Salter–Harris fracture that applies to the distal femur in children and adolescents with open growth plates. A type VI injury is an avulsion fracture of the periphery of the physis, resulting in an osteocartilaginous fragment comprising a portion of the perichondrial ring of the physis as well as small pieces of metaphyseal and epiphyseal bone. These may occur at many different anatomic sites but are seen most commonly about the physes of the distal fibula, distal femur, and distal tibia.32 The mechanism of distal femur injury is typically an indirect force such as varus stress that causes avulsion of the fragment from partial detachment of the proximal lateral collateral ligament, often resulting in no displacement of the epiphysis. Alternatively, open injuries that abrade or skeletonize the area around the physis or loss of a peripheral portion of the physis, such as occurs from lawnmower injuries or motor vehicle trauma, and burns around the physis are other possible mechanisms. This injury is not included in many large series of physeal fractures of the femur but it is exceedingly rare. In one series of 29,878 children's fractures, only 36 were identified as Salter–Harris VI injuries.32 

Classification by Displacement

Several authors have evaluated direction and magnitude of displacement to predict final outcome.2,37,50,83 Direction of displacement may guide treatment but does not predict the frequency of poor outcomes.2,37,80 Anterior displacement of the epiphysis, or apex posterior angulation, resulting from violent hyperextension of the knee is associated with an increased risk of neurovascular damage.21,80 Peroneal nerve injury may occur with significant medial or lateral displacement of the epiphysis. Otherwise, direction of displacement has not been shown to correlate with other complications such as angular deformity, growth disturbance, or loss of motion. 
By contrast, the magnitude of displacement has been shown to be predictive of complications.2,37,83 The critical amount of displacement that is associated with worsening outcomes varies but, generally, displaced fractures of all S-H types are more likely to develop complications compared to nondisplaced fractures. In one study, fractures with displacement of greater than 50% of the transverse diameter of the distal femoral metaphysis on either radiographic view were more likely to develop growth complications compared to less displaced fractures.83 Others have determined that displacement of more than one-third of bone width correlates with more frequent complications.2,37,50,83 Fractures without bony contact between the fragments and those with metaphyseal comminution,37 both radiographic indicators of high-energy trauma, have also been correlated with an increased risk of complications. 

Classification by Age

Age at the time of injury also correlates with the frequency and severity of complications.71 Distal femoral epiphyseal fractures in children aged 2 to 11 years typically result from high-energy mechanisms and have a poorer prognosis compared to fractures in children younger than 2 years of age or older than 11 years.24,71 Separations of the distal femoral epiphysis before the age of 2 years generally have satisfactory outcomes,71,83 possibly because epiphyseal undulations and the central peak are not as prominent in infants (Fig. 28-11A), allowing fractures to occur with less force and less damage to germinal cells and their blood supply.61 In adolescents, low-energy sports injuries are the most frequent cause of epiphyseal separation. Because children in this age group have little growth remaining, the consequences of growth disturbance, should this complication occur, are often trivial. In juveniles and adolescents, the fracture may pass through the central prominence and lead to central growth arrest because of interference with vascularity in this region or because of the fracture plane exiting and reentering the central physis (Fig. 28-11B).61,71,81 
Figure 28-11
 
A: Distal femoral physeal separation prior to the age of 2 years may not disrupt growth because the physis is flat. B: After the age of 2 years, a central ridge and four quadrants of undulation develop in the distal femur. Fractures in this age group are more likely to cross multiple planes of bone and cartilage.
A: Distal femoral physeal separation prior to the age of 2 years may not disrupt growth because the physis is flat. B: After the age of 2 years, a central ridge and four quadrants of undulation develop in the distal femur. Fractures in this age group are more likely to cross multiple planes of bone and cartilage.
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Figure 28-11
A: Distal femoral physeal separation prior to the age of 2 years may not disrupt growth because the physis is flat. B: After the age of 2 years, a central ridge and four quadrants of undulation develop in the distal femur. Fractures in this age group are more likely to cross multiple planes of bone and cartilage.
A: Distal femoral physeal separation prior to the age of 2 years may not disrupt growth because the physis is flat. B: After the age of 2 years, a central ridge and four quadrants of undulation develop in the distal femur. Fractures in this age group are more likely to cross multiple planes of bone and cartilage.
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Outcome Measures of Fractures of the Distal Femoral Physis

In the largest published series2,24,83 outcomes of distal femoral physeal fractures are determined by clinical assessment and radiographic parameters at follow-up. The primary clinical factors are the resulting neurovascular status of the affected limb and the range of motion of the knee. Secondarily, knee stability is assessed by subjective reporting of symptoms of instability and objective clinical stress testing of the knee ligaments. No study reported knee scores or the results of instrumented tests of knee ligament laxity. 
Radiographic assessment of the injured limb is utilized in most studies to assess fracture healing, to identify physeal bar formation, to measure angular deformity about the knee, and to assess for leg-length discrepancies that may result from a growth disturbance. Fracture healing is determined subjectively by identifying fracture line bridging as well as clinical signs of healing. Physeal bar formation may be identified on plain radiographs but also is assessed by MRI or CT scan. Angular deformity is determined by measuring angulation of the fracture fragments or the tibiofemoral angle. Although limb-length discrepancy may be determined clinically, bilateral lower extremity scanograms, obtained by the Bell–Thompson method or by CT scanning, are utilized to assess the true LLD. 

Surgical and Applied Anatomy Relating to Fractures of the Distal Femoral Physis

Ossification and Growth

The epiphysis of the distal femur is the first epiphysis to ossify and is present at birth, appearing as a small round bony structure distal to and in line with the axis of the metaphysis. This epiphyseal ossification center is the only radiographic sign of the larger cartilaginous anlagen of the distal femur. With maturation, the bony distal epiphysis enlarges as the cartilage model ossifies and becomes bicondylar, at times appearing irregular along the distal articular surface as ossification proceeds. From birth to skeletal maturity, the distal femoral physis contributes 70% of the growth of the femur and 37% of the growth of the lower extremity. The annual rate of growth is approximately three-eighths of an inch or 9 to 10 mm. The growth of the distal femur, like the physes of other long bones, ceases at a mean skeletal age of 14 years in girls and 16 years in boys, with a wide range of variability.1,87 

Physeal Anatomy

At birth, the distal femoral physis is flat, or planar, making this physis in infants the least stable compared to other age groups. With maturation, the physis assumes an undulating and more convoluted shape.47 By the age of 2 to 3 years, the physis develops an intercondylar groove, or central prominence, as well as sulci that traverse medial and lateral proximal to each condyle. This configuration effectively divides the physis into four quadrants, each with concave surfaces that match the four convex surfaces of the distal femoral metaphysis over a large surface area. The complex physeal geometry and large area of the distal femoral physis contribute to its stability by better resisting shear and torsional forces compared to the smaller, flat physes of infants. The perichondral ring also circumferentially reinforces the physis at its periphery. This structure, combined with the some reinforcement of the physeal periphery by the knee ligaments, provides additional resistance to disruption of the physis.18,56 During adolescence, however, the perichondrial ring becomes thinner. It is hypothesized that this change contributes to relative weakening of the distal femoral physis, partially explaining the fact that fractures of this physis in adolescents are more frequent and generally occur from lower energy mechanisms compared to children of 2 to 11 years of age. 
The irregular configuration of the physis, while contributing to stability, however, also is an important factor in the high incidence of growth disturbance from these fractures. Fracture lines, instead of cleanly traversing the hypertrophic zone and area of provisional calcification, extend through multiple regions of the physis and damage germinal cells regardless of fracture type.71 In addition, during reduction of displaced fractures, epiphyseal ridges may grind against the metaphyseal projections and further damage cartilage-producing resting cells. Minimizing contact and shear across the physis during reduction is preferable to improve the chances of normal growth after injury. Reductions in the operating room with muscle-relaxing agents, use of traction during reduction, and limiting the number of closed manipulation attempts before converting to open reduction are some techniques that are generally recommended. 

Bony Anatomy

Proximal to the medial border of the medial condyle, a small area of the metaphysis of the distal femur widens abruptly, forming the adductor tubercle. The lateral metaphysis, by contrast, flares only minimally at the proximal part of the lateral condyle, forming the lateral epicondyle. The distal femur is divided into two discrete condyles at the level of the knee joint, separated by the intercondylar notch. Nearly the entire distal femur is covered by hyaline cartilage for articulation with the proximal tibia. The anterior, or patellar, surface just proximal to the intercondylar notch, has a shallow midline concavity to accommodate the longitudinal convex ridge of the undersurface of the patella. Posteriorly, the distal femur contacts the tibial cartilage as the knee flexes. The posterior condyles, projections of the femoral condyles posteriorly, contain this cartilage that extends on either side of the intercondylar notch and nearly to the posterior margin of the physis. 
The distal femur has well-defined normal anatomical alignment parameters. The mechanical axis of the femur is formed by a line between the centers of the hip and knee joints (Fig. 28-12). A line tangential to the distal surfaces of the two condyles (the joint line) is in approximately 3 degrees of valgus relative to the mechanical axis. The longitudinal axis of the diaphysis of the femur inclines medially in a distal direction at an angle of 6 degrees relative to the mechanical axis and an angle of 9 degrees relative to the distal articular plane.34 
Figure 28-12
The mechanical and anatomic axis of the lower extremity.
 
Note that the knee joint is in a mean of 3 degrees of valgus. The femoral shaft intersects the transverse plane of the distal femoral articular surface at an angle of 87 degrees.
Note that the knee joint is in a mean of 3 degrees of valgus. The femoral shaft intersects the transverse plane of the distal femoral articular surface at an angle of 87 degrees.
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Figure 28-12
The mechanical and anatomic axis of the lower extremity.
Note that the knee joint is in a mean of 3 degrees of valgus. The femoral shaft intersects the transverse plane of the distal femoral articular surface at an angle of 87 degrees.
Note that the knee joint is in a mean of 3 degrees of valgus. The femoral shaft intersects the transverse plane of the distal femoral articular surface at an angle of 87 degrees.
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Soft Tissue Anatomy

The distal femoral physis is completely extrasynovial. Anteriorly and posteriorly, the synovial membrane and joint capsule of the knee attach to the femoral epiphysis just distal to the physis. The suprapatellar pouch, however, is a ballooning out of the synovium that extends proximally over the anterior surface of the metaphysis. On the medial and lateral surfaces of the epiphysis, the proximal attachment of the synovium and capsule is distal to the physis and separated from the physis by the insertions of the collateral ligaments. The strong posterior capsule and all of the major ligaments of the knee are attached to the epiphysis distal to the physis. Varus/valgus-directed forces that would cause collateral ligament disruption in adults often result in physeal separations in children and adolescents because the tensile strength of the ligaments is greater than that of the physis. The anterior and posterior cruciate ligaments originate in the upward-sloping roof of the intercondylar notch distal to the physis. Compression and tension forces can be transmitted across the extended knee to the epiphysis of the femur by taut ligaments. The medial and lateral heads of the gastrocnemius muscles originate from the distal femur proximal to the joint capsule and physis. Although forces generated by the gastrocnemius are probably not a major factor that contributes to fractures of the distal femoral physis, pull of the muscles may be a deforming force for metaphyseal fractures of the distal femur. 

Neurovascular Anatomy

Arterial Anatomy

The popliteal artery runs along the posterior surface of the distal femur, separated from it by only a thin layer of fat.20 Directly proximal to the femoral condyles, this artery sends off transverse branches medially and laterally, called the medial and lateral superior geniculate arteries, along the surface of the distal femoral metaphysis beneath the overlying muscles which they supply. The popliteal artery then continues distally, adjacent to the posterior capsule of the knee joint between the femoral condyles. At this level, the middle geniculate artery branches from it anteriorly to the posterior surface of the epiphysis, providing the primary blood supply to the distal femoral epiphysis and the physis. The distal femoral epiphysis, however, receives its blood supply from a rich anastomosis of vessels. Because of this, osteonecrosis of this epiphysis is exceedingly rare, occurring only in situations where distal femoral epiphysis is completely stripped of its soft tissue attachments. Since the popliteal artery and its branches course along the posterior distal femur, it is especially vulnerable to injury because of contact with the distal femoral metaphysis from hyperextension injuries of the knee with anterior displacement of the epiphysis. While tenting of the artery causing occlusion and arterial spasm are the most common reasons for vascular abnormalities related to distal femoral physeal fractures, intimal injury and laceration may also occur. 

Nerve Supply

The sciatic nerve, extending from the upper thigh, divides into the common peroneal and tibial nerves just proximal to the popliteal space. The peroneal nerve then descends posteriorly, between the biceps femoris muscle and the lateral head of the gastrocnemius muscle, to a point just distal to the head of the fibula. The peroneal nerve then changes course, wrapping around the proximal fibula to enter the anterior compartment of the lower leg, where it divides into the deep and superficial branches. The common peroneal nerve's course between muscles protects it from direct injury from fracture ends. This nerve, however, because of limited excursion due to its anteriorly directed course around the fibular head, is susceptible to injury from stretch. Neurapraxia, and even axonotmesis of the common peroneal nerve, results most commonly from fractures with severe anterior displacement and medial translation (varus displacement).80 The tibial nerve, coursing through the popliteal space adjacent to the popliteal artery, enters the calf along the arch of the soleus muscle. This nerve is vulnerable to injury from mechanisms that are similar to those that cause injury to the popliteal artery, although clinically tibial nerve injury is rare. 

Treatment Options for Fractures of the Distal Femoral Physis

Management Considerations for Fractures of the Distal Femoral Physis

Distal femoral physeal fractures in children and adolescents are challenging fractures that require careful preoperative evaluation and assessment of the injury including both physical and radiographic examinations so as to devise an appropriate treatment plan (Table 28-2). The treatment principles for these injuries can be summarized as follows. 
 
Table 28-2
Methods of Treatment for Distal Femoral Physeal Fractures
Treatment Pros Cons Indications
Closed reduction and immobilization Avoids anesthesia High risk of loss of reduction Nondisplaced, stable fractures
Closed reduction and screw fixation Minimal dissection Only in reducible fractures Reducible Salter–Harris type II fractures Nondisplaced Salter–Harris type III and IV fractures
Closed reduction and smooth pinning Minimal dissection Pins may lead to joint infection or require later removal Reducible Salter–Harris type I fractures, and Salter–Harris type II fractures with small metaphyseal fragment
Open reduction and screws and/or pins Anatomic reduction Stiffness Irreducible Salter–Harris type I and II fractures, displaced Salter–Harris type III and IV fractures
External fixation Allows soft tissue access Pin site (joint) infection Severe soft tissue injury
Rigid plate crossing physis Rigid fixation Can stop future growth when spans physis Adolescents near the end of growth. Severe injuries with growth disturbance inevitable
Possible temporary fixation with extraperiosteal locked plating removed soon after union
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  1.  
    Restore the anatomy without iatrogenically compromising the distal femoral physis.
  2.  
    Stabilize the fracture in the position of anatomic reduction.
The surgeon must keep in mind that by definition there has already been an injury to the physis and further damage to the physis by repeated or forceful manipulations may contribute to one of the complications of this injury, premature physeal closure. Closed reduction of these injuries must be done gently, preferably under either under IV sedation or general anesthesia, so that this reduction be accomplished easily with minimal force. Once the reduction has been achieved, maintaining it has been shown to be vitally important for influencing outcome (as redisplaced fractures tend to have poor prognosis and higher complication rates).7,83 Treatment is also guided by the Salter type. Salter types III and IV are intra-articular and require an anatomic reduction to minimize the potential for future arthritis and degenerative joint disease. Therefore these fractures are most commonly treated with open reduction and internal fixation to restore anatomic integrity of the joint surface. The ultimate goals of treatment are to maintain anatomic alignment of the lower extremity, preserve range of motion in the knee joint, and not disturb ongoing growth of the distal femoral physis.9 

Closed Treatment of Fractures of the Distal Femoral Physis

Nondisplaced or minimally displaced distal femoral physeal fractures especially Salter I or Salter II fractures, may be treated with, a gentle closed reduction and immobilization in a cast. Conceivably even a Salter III or Salter IV fracture that was completely nondisplaced could also be managed in this manner. The treating surgeon must be cognizant of the fact that displacement may have been far greater at the time of injury than the injury radiographs depict. At the time of the injury, the periosteum and/or resilience of the child's bone as well as reduction at the site of injury may have occurred, rendering the acute trauma or injury films to be either non- or minimally displaced.9 Evidence of considerable soft tissue injury such as swelling, ecchymosis, and/or other skin changes may also be an indication that the fracture was more displaced at the time of injury. 
If minimal force is required to perform a reduction, most series indicate that these fractures can still be successfully managed in this manner. This technique of a closed reduction and immobilization in a long-leg cast has been performed primarily in minimally or nondisplaced Salter I and II fractures. 
Careful assessment of stability of the fracture by the surgeon is crucial to having a successful outcome with closed reduction and manipulation. In a recent study of 82 patients immobilized in a long-leg cast, 36% had redisplacement in the first 2 weeks including three patients in a series of 29 immobilized with a hip spica cast.24 Of the 32 patients that displaced in a cast in this study, only eight were successfully remanipulated. Closed reduction and casting is never the best definitive treatment for displaced or unstable distal femoral physeal fractures because of the significant risk of fracture redisplacement.2 Persistent widening after provisional reduction may reflect interposed periosteum and lead to reduction less than anatomic and more likely to redisplace.9 Recent literature suggests that periosteal interposition may theoretically place the physis at increased risk for closure.75 Anatomic reduction is always the goal with these injuries and if an adequate reduction cannot be obtained by closed means, alternative methods of treatment must be utilized. 

Techniques of Reduction

Displaced distal femoral physeal fractures with more than 2 mm of malalignment typically require reduction and surgical stabilization with internal fixation. The overriding principle regarding reduction maneuvers is to avoid further injury to the physis (Fig. 28-13). Most authors recommend that the reductions be done with the patient relaxed with muscle relaxants or under general anesthesia. However, so-called gentle reduction does not preclude the possibility of growth arrest, as has been noted by Thomson et al.83 The technique of reduction relies on assessment of the fracture pattern. In a general sense, the concave side of the fracture would be gently manipulated to realign it with the long axis or shaft of the femur, essentially closing down the convexity of the fracture. The periosteum is typically intact on the concave side of the injury. For example, the periosteum on the side of the Thurston Holland fragment for Salter II fractures is usually intact, but disrupted on the convex side of the fracture. Periosteal interposition at the fracture site is a frequent occurrence in these fractures and necessitates careful assessment of the postreduction imaging and anatomy. 
Figure 28-13
Closed reduction of a Salter–Harris type I or II fracture.
 
A: With medial or lateral displacement, traction is applied longitudinally along the axis of the deformity to bring the fragments back to length. B: For anterior displacement, the reduction can be done with the patient prone or supine. Length is gained first, then a flexion moment is added.
A: With medial or lateral displacement, traction is applied longitudinally along the axis of the deformity to bring the fragments back to length. B: For anterior displacement, the reduction can be done with the patient prone or supine. Length is gained first, then a flexion moment is added.
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Figure 28-13
Closed reduction of a Salter–Harris type I or II fracture.
A: With medial or lateral displacement, traction is applied longitudinally along the axis of the deformity to bring the fragments back to length. B: For anterior displacement, the reduction can be done with the patient prone or supine. Length is gained first, then a flexion moment is added.
A: With medial or lateral displacement, traction is applied longitudinally along the axis of the deformity to bring the fragments back to length. B: For anterior displacement, the reduction can be done with the patient prone or supine. Length is gained first, then a flexion moment is added.
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For a Salter II fracture that is displaced into valgus alignment such as the epiphysis is displaced laterally and there is a lateral Thurston Holland fragment of metaphysis attached to the epiphysis, the reduction maneuver would involve gentle longitudinal traction often with the knee flexed slightly and counter pressure applied over the distal medial femur while the epiphyseal portion of the fracture is gently guided back in place. More challenging reductions occur in the sagittal plain when the epiphysis is displaced either anteriorly or posteriorly. Anteriorly displaced physeal fractures generally require some level of knee flexion to achieve reduction. In all reductions, generally longitudinal traction is the first force applied followed by the gentle manipulation of the epiphysis back into place starting with counterpressure on the proximal segment in an opposite direction. For a displaced epiphysis that is anterior, holding the fracture reduced may require a significant amount of knee flexion, which especially in a swollen knee, which may not be advisable from a neurovascular standpoint. Fractures like these may require internal stabilization with pins simply to be able to splint the knee in slight flexion. Some authors recommend aspiration of the knee or the hematoma that may be present especially in Salter III or IV fractures prior to closed reduction maneuvers. Various reports indicate redisplacement of reduced fractures in a cast of 30% or higher such that there has been a tendency for internal stabilization with implants for displaced fractures.83 A recent report indicated that internal fixation is the preferred method of treatment for all displaced injuries.2 

Technique of Closed Reduction and Percutaneous Pinning

One of the most common methods that displaced distal femoral physeal fractures are stabilized is a technique of percutaneous internal fixation with pins or screws (Fig. 28-14). These fractures can often be reduced fairly anatomically and given their propensity to be unstable, fixation with crossed pins or with a screw or two through the Thurston Holland fragment in the case of Salter II fractures provides stable internal fixation of the fracture. Even Salter III and IV fractures can be treated this way if there is minimal displacement on the injury films and an anatomic reduction can be achieved by closed means. 
Figure 28-14
Screw fixation following closed or open reduction of Salter–Harris type II fracture with a large metaphyseal fragment.
 
A: When using cannulated screws, place both guidewires before screw placement to avoid rotation of the fragment while drilling or inserting screw. Screw threads should be past the fracture site to enable compression. Washers help increase compression. Screws may be placed anterior and posterior to each other, which is particularly helpful when trying to fit multiple screws in a small metaphyseal fragment. B: This form of fixation is locally “rigid,” but must be protected with long-leg immobilization.
A: When using cannulated screws, place both guidewires before screw placement to avoid rotation of the fragment while drilling or inserting screw. Screw threads should be past the fracture site to enable compression. Washers help increase compression. Screws may be placed anterior and posterior to each other, which is particularly helpful when trying to fit multiple screws in a small metaphyseal fragment. B: This form of fixation is locally “rigid,” but must be protected with long-leg immobilization.
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Figure 28-14
Screw fixation following closed or open reduction of Salter–Harris type II fracture with a large metaphyseal fragment.
A: When using cannulated screws, place both guidewires before screw placement to avoid rotation of the fragment while drilling or inserting screw. Screw threads should be past the fracture site to enable compression. Washers help increase compression. Screws may be placed anterior and posterior to each other, which is particularly helpful when trying to fit multiple screws in a small metaphyseal fragment. B: This form of fixation is locally “rigid,” but must be protected with long-leg immobilization.
A: When using cannulated screws, place both guidewires before screw placement to avoid rotation of the fragment while drilling or inserting screw. Screw threads should be past the fracture site to enable compression. Washers help increase compression. Screws may be placed anterior and posterior to each other, which is particularly helpful when trying to fit multiple screws in a small metaphyseal fragment. B: This form of fixation is locally “rigid,” but must be protected with long-leg immobilization.
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Preoperative planning and room setup for percutaneous pinning would involve the use of a radiolucent table although a traction-type table is usually not necessary. Obviously, imaging must be available, as well as the appropriate instrumentation, typically cannulated large fragment screws and smooth Steinmann pins. Muscle relaxation of the patient provided by the anesthesiology team is especially helpful before initiating reduction maneuvers. Neurovascular status of the extremity should be checked routinely both before and after reduction maneuvers. At times, reduction is facilitated by placing a bump under the patient's thigh. In the case of flexion or extension-type physeal displacement, these injuries may actually be managed in a prone position. The actual technique would require closed reduction to be accomplished with virtually anatomic alignment as discussed previously. In terms of a Salter I or Salter II fracture without a significant Thurston Holland fragment, the technique involves placing typically retrograde two large Steinmann pins. These are frequently 3.2-mm or even larger diameter smooth pins. With x-ray guidance and the reduction held by an assistant, a small incision is usually made laterally over the condyle in midpoint. The placement of the pin is not in the articular cartilage but just off the articular margin in the epiphyseal bone and directed slightly anteriorly to avoid injury to the posterior neurovascular structures (Fig. 28-15). It may be more helpful to start with the pin on the side that was the concave side of the fracture pattern. Two pins are typically placed. Careful assessment radiographically should be done with C-arm imaging in both AP and lateral planes. 
Figure 28-15
 
A: Clinical photo of right S-H II right knee; note swelling compared to normal left knee. B: Photo of knee showing guide pin for cannulated screw in place in Thurston Holland fragment. Vertical line marks cephalad extent of TH fragment. Smaller line marks the physis. C: Preparing entry site for second guide pin with C-arm guidance. D: Using a hemostat to spread IT band and periosteum and to create path to distal femur for pin placement. E: Placing guide pin parallel to original pin. F: Two pins in distal femur, parallel and verified in good position with C-arm. G: Measuring depth of guide pin to determine screw length. Note a third pin was added. H: Drilling over guide pin: Note that far cortex does not need to be drilled. I: Placing cannulated cancellous screw. J: Appearance after screws are placed. K: Appearance after wound closure. L: Dressing in place. M: Final cast in place.
A: Clinical photo of right S-H II right knee; note swelling compared to normal left knee. B: Photo of knee showing guide pin for cannulated screw in place in Thurston Holland fragment. Vertical line marks cephalad extent of TH fragment. Smaller line marks the physis. C: Preparing entry site for second guide pin with C-arm guidance. D: Using a hemostat to spread IT band and periosteum and to create path to distal femur for pin placement. E: Placing guide pin parallel to original pin. F: Two pins in distal femur, parallel and verified in good position with C-arm. G: Measuring depth of guide pin to determine screw length. Note a third pin was added. H: Drilling over guide pin: Note that far cortex does not need to be drilled. I: Placing cannulated cancellous screw. J: Appearance after screws are placed. K: Appearance after wound closure. L: Dressing in place. M: Final cast in place.
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A: Clinical photo of right S-H II right knee; note swelling compared to normal left knee. B: Photo of knee showing guide pin for cannulated screw in place in Thurston Holland fragment. Vertical line marks cephalad extent of TH fragment. Smaller line marks the physis. C: Preparing entry site for second guide pin with C-arm guidance. D: Using a hemostat to spread IT band and periosteum and to create path to distal femur for pin placement. E: Placing guide pin parallel to original pin. F: Two pins in distal femur, parallel and verified in good position with C-arm. G: Measuring depth of guide pin to determine screw length. Note a third pin was added. H: Drilling over guide pin: Note that far cortex does not need to be drilled. I: Placing cannulated cancellous screw. J: Appearance after screws are placed. K: Appearance after wound closure. L: Dressing in place. M: Final cast in place.
View Original | Slide (.ppt)
A: Clinical photo of right S-H II right knee; note swelling compared to normal left knee. B: Photo of knee showing guide pin for cannulated screw in place in Thurston Holland fragment. Vertical line marks cephalad extent of TH fragment. Smaller line marks the physis. C: Preparing entry site for second guide pin with C-arm guidance. D: Using a hemostat to spread IT band and periosteum and to create path to distal femur for pin placement. E: Placing guide pin parallel to original pin. F: Two pins in distal femur, parallel and verified in good position with C-arm. G: Measuring depth of guide pin to determine screw length. Note a third pin was added. H: Drilling over guide pin: Note that far cortex does not need to be drilled. I: Placing cannulated cancellous screw. J: Appearance after screws are placed. K: Appearance after wound closure. L: Dressing in place. M: Final cast in place.
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Figure 28-15
A: Clinical photo of right S-H II right knee; note swelling compared to normal left knee. B: Photo of knee showing guide pin for cannulated screw in place in Thurston Holland fragment. Vertical line marks cephalad extent of TH fragment. Smaller line marks the physis. C: Preparing entry site for second guide pin with C-arm guidance. D: Using a hemostat to spread IT band and periosteum and to create path to distal femur for pin placement. E: Placing guide pin parallel to original pin. F: Two pins in distal femur, parallel and verified in good position with C-arm. G: Measuring depth of guide pin to determine screw length. Note a third pin was added. H: Drilling over guide pin: Note that far cortex does not need to be drilled. I: Placing cannulated cancellous screw. J: Appearance after screws are placed. K: Appearance after wound closure. L: Dressing in place. M: Final cast in place.
A: Clinical photo of right S-H II right knee; note swelling compared to normal left knee. B: Photo of knee showing guide pin for cannulated screw in place in Thurston Holland fragment. Vertical line marks cephalad extent of TH fragment. Smaller line marks the physis. C: Preparing entry site for second guide pin with C-arm guidance. D: Using a hemostat to spread IT band and periosteum and to create path to distal femur for pin placement. E: Placing guide pin parallel to original pin. F: Two pins in distal femur, parallel and verified in good position with C-arm. G: Measuring depth of guide pin to determine screw length. Note a third pin was added. H: Drilling over guide pin: Note that far cortex does not need to be drilled. I: Placing cannulated cancellous screw. J: Appearance after screws are placed. K: Appearance after wound closure. L: Dressing in place. M: Final cast in place.
View Original | Slide (.ppt)
A: Clinical photo of right S-H II right knee; note swelling compared to normal left knee. B: Photo of knee showing guide pin for cannulated screw in place in Thurston Holland fragment. Vertical line marks cephalad extent of TH fragment. Smaller line marks the physis. C: Preparing entry site for second guide pin with C-arm guidance. D: Using a hemostat to spread IT band and periosteum and to create path to distal femur for pin placement. E: Placing guide pin parallel to original pin. F: Two pins in distal femur, parallel and verified in good position with C-arm. G: Measuring depth of guide pin to determine screw length. Note a third pin was added. H: Drilling over guide pin: Note that far cortex does not need to be drilled. I: Placing cannulated cancellous screw. J: Appearance after screws are placed. K: Appearance after wound closure. L: Dressing in place. M: Final cast in place.
View Original | Slide (.ppt)
A: Clinical photo of right S-H II right knee; note swelling compared to normal left knee. B: Photo of knee showing guide pin for cannulated screw in place in Thurston Holland fragment. Vertical line marks cephalad extent of TH fragment. Smaller line marks the physis. C: Preparing entry site for second guide pin with C-arm guidance. D: Using a hemostat to spread IT band and periosteum and to create path to distal femur for pin placement. E: Placing guide pin parallel to original pin. F: Two pins in distal femur, parallel and verified in good position with C-arm. G: Measuring depth of guide pin to determine screw length. Note a third pin was added. H: Drilling over guide pin: Note that far cortex does not need to be drilled. I: Placing cannulated cancellous screw. J: Appearance after screws are placed. K: Appearance after wound closure. L: Dressing in place. M: Final cast in place.
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X
Fracture stability may also be assessed by gently applying varus, valgus, or flexion–extension force once pins are in place. Some authors will leave the pins external in this area. Some will bend them slightly and cut them short and leave them under the skin. Other authors advocate driving the pins out and through the metaphysis of the bone such that they are flush with the edge of the epiphysis at the entry site and bend them externally above the knee. One concern with external pins in this area is the issue that the joint itself could be contaminated since the pins are essentially intra-articular, hence the reason some surgeons drive the pins proximally to exit through the metaphysis.9 Starting the pins proximally in the metaphysis and placing them across the fracture in an antegrade fashion and ending them in the subchondral bone of the epiphysis is becoming more popular in some centers to minimize pin tract infections that could communicate with the joint. Typically patients are immobilized in a fiberglass long-leg cast with the knee gently flexed. 
Distal femoral physeal fractures heal readily and are healed within 4 weeks at which point pins may be removed. Touchdown weight bearing in the cast may be allowed in the last week or two prior to pin removal. Often a splint or hinged knee brace is used for a few weeks to facilitate regaining range of motion of the knee with increasing weight bearing, such that most patients are able to bear weight fully about 6 weeks post-op. Pin removal at 4 weeks may be done in the office if the pins are external or as a day surgery procedure if they were buried beneath the skin. The patients are instructed to work on quad strengthening and active range of motion of the knee often facilitated by physical therapy. 

Screw Fixation

The technique for stabilizing a Salter II fracture with a significant metaphyseal fragment again involves performing a gentle closed reduction under anesthesia. A small incision is then made in the metaphysis over the Thurston Holland fragment which typically is either on the medial or lateral aspect of the distal femur. The guide pins from the cannulated screw systems are used to help stabilize the fracture. Typically only drilling the outer cortex is necessary and either one or two 6.5 or larger screws are utilized to stabilize the fracture fragment. Care must be taken to ensure that the screws do not approach or cross the physis. Generally, screws are placed in a manner that is parallel to the distal femoral physis. Again assessment of fracture stability by gentle stress with the hardware in and secure is helpful to ensure that internal fixation is adequate in providing optimum stability. Postoperative treatment would be the same with typically long-leg casting for 4 weeks. Screw removal is at the discretion of the family and surgeon at a convenient time in the future. Occasionally the Thurston Holland permits only one screw to be placed. These fractures may be unstable enough that one screw is insufficient to provide adequate internal fixation. It is not uncommon that a single screw in a Salter II fracture may be supplemented with a Steinmann pin in the fashion as described for percutaneous pinning. If one Steinmann pin is to be used, it would ideally enter on the side opposite the entry of the screw to provide stability of the fracture. 

Closed Reduction and Screw Fixation of Salter III and IV Fractures

Minimally displaced Salter III fractures may also be managed with percutaneous reduction and screw fixation. The use of reduction bone forceps or clamps may be helpful in closing down a gap or diastasis of the condyles. Again, careful and accurate assessment of intraoperative imaging is essential to ascertain whether the reduction is adequate for percutaneous technique versus an open reduction. Screw placement in a Salter III or IV fracture may be done in the epiphysis with x-ray guidance using a cannulated screw system. Care must be taken not to place the screws too distal in the epiphysis such that they would impinge on the intercondylar notch of the femur. Again typically two screws possibly placed one more anterior and one more posterior would be utilized to stabilize a Salter III fracture internally. A Salter IV fracture may have a metaphyseal fragment that is sufficiently large enough to be stabilized with a screw. The epiphyseal portion or the Salter IV fracture may then be stabilized by another screw (Fig. 28-16). 
Figure 28-16
Open reduction of displaced lateral Salter–Harris type IV fracture of the distal femur.
 
A: A longitudinal skin incision is made anteriorly on the knee at the location of the intra-articular fracture or in the midline if fracture severity raises concern of needing a total knee replacement in the future. B: Alignment of joint and physis are used to judge reduction. Guidewires for cannulated screws placed above and below physis, parallel to physis. C: Screws inserted in compression with washer on metaphyseal fragment. Washer is optional in epiphyseal fragment if later prominence is of more concern than need for additional compression.
A: A longitudinal skin incision is made anteriorly on the knee at the location of the intra-articular fracture or in the midline if fracture severity raises concern of needing a total knee replacement in the future. B: Alignment of joint and physis are used to judge reduction. Guidewires for cannulated screws placed above and below physis, parallel to physis. C: Screws inserted in compression with washer on metaphyseal fragment. Washer is optional in epiphyseal fragment if later prominence is of more concern than need for additional compression.
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Figure 28-16
Open reduction of displaced lateral Salter–Harris type IV fracture of the distal femur.
A: A longitudinal skin incision is made anteriorly on the knee at the location of the intra-articular fracture or in the midline if fracture severity raises concern of needing a total knee replacement in the future. B: Alignment of joint and physis are used to judge reduction. Guidewires for cannulated screws placed above and below physis, parallel to physis. C: Screws inserted in compression with washer on metaphyseal fragment. Washer is optional in epiphyseal fragment if later prominence is of more concern than need for additional compression.
A: A longitudinal skin incision is made anteriorly on the knee at the location of the intra-articular fracture or in the midline if fracture severity raises concern of needing a total knee replacement in the future. B: Alignment of joint and physis are used to judge reduction. Guidewires for cannulated screws placed above and below physis, parallel to physis. C: Screws inserted in compression with washer on metaphyseal fragment. Washer is optional in epiphyseal fragment if later prominence is of more concern than need for additional compression.
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Challenges or problems with the technique of a closed reduction and internal fixation with pins or screws include an inadequate reduction that may be secondary to periosteal interposition. As mentioned, the periosteum is often torn on the convex side so an incomplete reduction that has still a wide physis on the convex side may need to be opened on that side to extract the periosteum to ensure an adequate, stable, and anatomic reduction. Interposed periosteum has been shown experimentally to increase the risk of growth disturbance.67 In addition, when trying to utilize this technique for Salter III or Salter IV fractures, if the articular surface cannot be well aligned or if there is comminution present, an open approach would be necessary. Likewise, comminution of the metaphysis may make screw fixation of a Thurston Holland fragment difficult, necessitating that some Salter II fractures be fixed internally in a stable configuration with transphyseal pins and not screws. The technique of utilizing transphyseal pins to stabilize distal femoral physeal fractures requires the use of smooth pins to minimize injury to the physis. A recent paper looked specifically at the issue of physeal injury and subsequent growth arrest to determine if the pins could possibly be the culprit causing the arrest.27 The conclusion of this work was that the pins themselves were not the primary cause of the subsequent physeal arrest or growth disturbance. This potential for physeal arrest varied with increasing severity based on the Salter–Harris classification and percutaneous smooth pins were not statistically associated with the growth arrest.27 

Reduction and Internal Fixation

Open reduction and internal fixation is necessary for all irreducible distal femoral physeal fractures. Irreducible fractures may have interposed periosteum on the side of the open physis or the convex side of the fracture. An incision is necessary over that area whether it is medial or lateral; even in sagittal plane displacements, typically the incision is still on the medial or lateral aspect. The periosteum is carefully removed from the physis and care is taken to avoid causing any more injury to the physis by surgical instruments or retractors.9 Evacuation of organized hematoma is helpful to achieve anatomic reduction. Internal fixation may proceed accordingly with either pins or screws as warranted. 
Fractures that undergo open reduction and internal fixation may be more prone to get stiff and healing by 4 weeks remains the norm with early mobilization of the knee recommended starting at about 4 weeks. 

Other Means of Fixation

The use of external fixators in open fractures of the knee involving the distal femoral physis may be a helpful means of managing severe soft tissue trauma and injuries. Typically one or even two half pins from an external fixation frame may be placed in the epiphysis of the fracture with 2 pins placed in the femoral shaft. Salter III and IV fractures may be somewhat more difficult to manage with the external fixation technique. Fixation across the knee may be necessary. 
Another means of fixation is a plate spanning the physis. A recent paper from France described good outcomes with this technique.37 The plates were removed at a relatively early interval to minimize any growth disturbance and screw insertion and placement occurred so as to avoid the physis. Absorbable screws have also been utilized in some of these patients. There is little current literature on this technique. 
In Salter III and Salter IV fractures, arthroscopically aided reduction of the fracture may be helpful in somewhat minimally displaced fractures to ensure an anatomic reduction of the joint line and articular cartilage.44 In addition, visualization of the knee joint, whether with arthroscopy or at the time of arthrotomy, permits assessment for other associated injuries such as ligamentous injuries or meniscal injuries. 
Most authors recommend dealing with intra-articular ligamentous injuries later after the fracture has healed. Peripheral tears of the meniscus may be repaired primarily at the time of an operative open reduction. As in most current protocols for ACL reconstruction, resolution of the acute phase swelling and in this case fracture healing and rehabilitation would be accomplished prior to consideration of ACL reconstruction. 
For those fractures associated with vascular injuries, typically full and rapid reduction of the fracture and stabilization is necessary. If there is still a vascular compromise of the leg, the orthopedic surgical team may consider compartment pressure monitoring and/or fasciotomies as warranted while the vascular team is evaluating the need for intervention for an occluded artery.9 

Author's Preferred Treatment of Fractures of the Distal Femoral Physis

Key Concepts

The critical factor in distal femoral physeal fractures is the amount of energy sustained by the distal femoral physis which often determines the outcome and future growth of the physis. The management of these fractures must be focused on minimizing further injury or trauma to the physis, especially with reduction maneuvers. Displaced fracture reduction must be done easily, gently, and in a relaxed patient. Often the fractures reduce with longitudinal traction and a little medial or lateral pressure; physeal fractures elsewhere in the skeletal system often do not require a lot of force. Repeated forceful reductions must be avoided to minimize potential iatrogenic injury to the physis. Treatment principles really are based on the Salter–Harris classification as well as the amount and degree of displacement. The authors have a very low threshold for operative stabilization of these fractures with pins or screws as needed. 
For nondisplaced and stable fractures regardless of Salter type, the authors are comfortable with a well-molded long-leg cast. In children with certain body types, especially obese patients that are relatively short stature, cast immobilization may not provide fracture stability. Treatment must be individualized to the specific patient and consideration given to the possibility that casting may not adequately stabilize a nondisplaced fracture. The treating surgeon must recall that what appears nondisplaced on radiographs in the emergency room may have displaced and returned to normal anatomic positioning at the time of injury, and not lulled into a false sense of fracture stability for “nondisplaced” fractures. 
Should cast immobilization be elected as a treatment option for nondisplaced fractures, seeing the patient back in the office and obtaining the x-rays within 4 to 5 days is recommended to ensure that the fracture reduction is maintained or to identify loss of anatomic position as early as possible. Literature indicates that loss of reduction and rereduction of fractures is associated with a higher incidence of physeal growth arrest, but accepting a malalignment is also less than ideal for the patient's functional outcome. 

Displaced Salter–Harris I and II Fractures

Many Salter I and Salter II fractures of the distal femoral physis that are displaced can be managed by a reduction in the operating room and stabilization with internal fixation. If one or two screws can be placed through the Thurston Holland fragment to stabilize a Salter II fracture, it would certainly be the desired treatment. Large Steinmann pins are also commonly utilized to stabilize both Salter I and Salter II fractures as needed. Typically these patients are then managed with 4 weeks of long-leg casting, removal of the cast around 4 weeks, and use of a knee immobilizer or hinged knee brace for initiation of early motion. Therapy may be helpful for these patients to assist with regaining range of motion, but the therapist must be cautioned against any forcible passive manipulation in the early post casting phase. Most patients seem to be off crutches and ambulating fairly well by 7 or 8 weeks postinjury. 

Displaced Salter–Harris III and IV Fractures

Displaced intra-articular fractures that involve the distal femoral physis require careful scrutiny of the fracture alignment and pattern preoperatively and especially careful assessment of the intraoperative imaging. Salter III or IV fractures may require open reduction and internal fixation to ensure anatomic restoration of the articular cartilage. This can sometimes be done with a closed percutaneous reduction, sometimes with the bone reduction forceps, and then percutaneous cannulated screw fixation. A number of authors point out that imaging with the image intensifier or C-arm in the OR may not be the most accurate way to assess post-op reduction in a fracture like this. The other option would be to obtain true hard copy radiographs with a standard machine intraoperatively. One option is to utilize arthroscopy as a means to assess the joint alignment and integrity. The authors do not have extensive experience with arthroscopically assisted reduction of these fractures, but in some centers this is becoming a routine procedure for Salter III and IV fractures. The post-op regimen is the same with casting for 4 weeks and then initiation of early motion and particularly in these patients a hinged knee brace versus knee immobilizer may also be very helpful. 
The authors explain to all distal femoral physeal fracture patients and their families that these physeal injuries of all Salter types may have a long-term guarded prognosis regarding growth of the physis. Follow-up is done essentially at monthly intervals for the first several months; usually the 1-month visit is a day surgical procedure to remove pins. Screw removal of the cannulated screws done percutaneously is left to the discretion of the family. Occasionally these are removed if MRI imaging is needed to assess the physis. Follow-up should be scheduled at 3 months, approximately four-and-a-half months and 6 months postinjury to specifically assess alignment of the extremity length and carefully assess radiographs for signs of physeal injury or arrest. 

Surgical Complications of Fractures of the Distal Femoral Physis

Impending Complications

As has been mentioned these distal femoral physeal injuries require significant trauma to be sustained by the extremity to cause displacement of the physis. With that amount of force or pressure other associated injuries may occur. Those patients with displaced fractures in particular must be carefully assessed for neurovascular status at the time of injury in the emergency room. For Salter II distal femoral physeal fractures that displace the epiphysis anteriorly, the distal portion of the femoral artery or popliteal artery is at risk from the distal end of the segment of the femur. Careful assessment of the pulses and circulation to the foot are essential. In patients with a documented vascular compromise or white foot, this reduction and surgery is truly an operative emergency and careful assessment post-op for return of vascular status is necessary. Consultation with the vascular surgical team is often necessary if concerns of vascular status remain postreduction. Vascular imaging may be needed to assess circulation if pulses are still diminished following reduction and stabilization of the distal femoral physeal fracture. Likewise some of these patients may sustain such injury to the leg that a compartment syndrome could ensue, so careful monitoring of the compartments by clinical examination or if needed by compartment pressure measurements may be necessary. 

Malalignment and Poor Reduction or Loss of Reduction

Often displacement in distal femoral physeal fractures can be significant. In an operating room with muscle relaxation, reduction can often be accomplished without significant force by simply placing traction on the leg and guiding the epiphysis back into position. Careful assessment both clinically and radiographically of leg alignment and fracture reduction needs to be done to ensure that as anatomically as possible a reduction is achieved. Reduction that remains malaligned in either the coronal or sagittal plane may persist in that malalignment and require subsequent late constructive surgery. It is especially critical to accurately assess imaging in the operating room to ensure that physeal widening, which may be subtle, is not present. 
Interposed periosteum may cause physeal widening and block a more anatomic reduction as well as contribute to fracture instability that could lead to loss of reduction in a casted patient postoperatively. The treating surgeon should have a low threshold to make an incision and inspect the fracture to ensure there is no soft tissue impeding reduction in cases that may look less than anatomically reduced. 
When a loss of reduction of what was thought to be a stable nondisplaced fracture in a cast is noted, the patient should be expeditiously returned to the operating room and anatomic alignment reestablished as easily and safely as possible. In this situation, if the patient had previously been treated with casting only, it is necessary to add internal fixation in the form of pins or screws as appropriate to stabilize that patient's fracture. 

Fixation

Many of these fractures do not have sizable Thurston Holland fragments in the Salter I or II category that would enable screw fixation. Many of the patients are managed with pin fixation with transphyseal pinning techniques. The surgeon must ensure that an adequate pin size is used. Typically in the author's experience this is a minimum of 2.4- or 2.8-mm pin diameter and in larger patients even 3.2-mm diameter pins must be used. Intraoperative imaging should ensure that these pins are bicortical and have good purchase in both the distal and proximal fracture fragments. 

Infection

The literature substantiates that infection and in fact septic knee arthritis may result from pins left externally that are placed in a retrograde manner in the epiphysis on either side of the knee joint. The author's preferred technique is to not leave these pins exposed outside the skin. If the pin can be gently bent, it is bent and cut in such way that the pin is inside the skin with the wound closed over it. Another technique described by Blaiser13 places the pins retrograde across the physis and advances them up through the skin proximal to the knee joint. The pins left are flush with edge of the condyle or epiphysis distally. The areas can be closed and the pins are external above the knee joint. Closing the skin over the retrograde pinning entry sites helps minimize the risk of intra-articular sepsis in these patients. In the event of a true infection the patient is returned to the operating room for irrigation and debridement. The pins may have to be left in if the fracture is not sufficiently healed at least 4 weeks postinjury. Appropriate antibiotic treatment and surgical wound management are necessary in these cases of an infection, especially in the first few weeks following the injury. 

Management of Expected Adverse Outcomes and Unexpected Complications

In the immediate postoperative period, loss of reduction and neurovascular injuries are important complications. In follow-up, the most common complications of distal femoral physeal fractures include knee ligament injury, growth disturbances of the distal femur, neurovascular complications from the fracture and persistent knee stiffness (Tables 28-3 and 28-4). 
 
Table 28-3
Distal Femoral Physeal Fractures: Pitfalls and Prevention
Pitfall Preventative Strategy
Missed diagnosis Immobilize and reexamine if uncertain, or MRI
Be cognizant of nondisplaced injury in infants, pathologic conditions, multitrauma, or unresponsive patients
Redisplacement of fracture Pin or screw fixation for all fractures that require reduction. Radiographs at 5–7 days postinjury
High long-leg cast with triangular molding proximally or spica cast
Growth disturbance Minimize trauma at reduction
Follow-up at 6, 12, and possibly 24 months with full-length radiographs of both lower extremities
Knee joint instability Check ligaments when fracture stabilized or healed. Consider MRI, especially for type III fractures
Stiffness Avoid prolonged immobilization
Remove casts in 4 weeks and apply knee immobilizer with gentle range of motion in most cases. Avoid manipulation because of risk of added injury
X
 
Table 28-4
Complications of Fractures of the Distal Femoral Physis
View Large
Table 28-4
Complications of Fractures of the Distal Femoral Physis
Number of Patients Ligamentous Injury (%) Neurovascular Problems (%) Angular Deformity (%) Shortening (%) Stiffness (%)
Stephens and Louns82 20 25 5 25 40 25
Lombardo and Harvey50 34 23 3 33 35 33
Czitrom et al.21 41 0 2.5 41 14% clinical
58% radiographic
22
Riseborough et al.7(a) 133a 4 25 55 23
Thomson et al.83 30 Two anterior cruciate ligament injuries 18 47 18
Eid and Hafez24 151 8% symptomatic 14% asymptomatic 10 51 38 29
Ilharreborde et al.37(b) 20 0 55 40 25
Arkader et al.2 73 1 12 12 4
X

Loss of Reduction

Redisplacement after closed reduction of distal femoral physeal separations has been reported in 30% to 70% of patients immobilized in a long-leg cast.24,29,71,83 Placement of a hip spica cast may reduce this loss of reduction to as low as 10%.24 Multiple attempts at initial closed reduction, and late reduction after injury or after a failed first attempt at reduction, are potentially damaging to the physis and may increase the risk of growth disturbance.70 In one experimental rat model, risk of physeal injury was similar for fractures reduced after the equivalent of 7 human days. After 10 days, however, manipulation of physeal fractures led to diaphyseal fractures because of the degree of physeal healing.23 Based on the experimental evidence and clinical experience, it is reasonable to attempt manipulation, or repeat manipulation, of physeal fractures of the distal femur within 7 to 10 days of injury. After 10 days, however, open reduction may be required to reestablish alignment and to minimize damage to the physis. For children with more than 2 years of growth remaining who have Salter–Harris I and II fractures, observation for remodeling may be more prudent, depending on the degree of deformity. Osteotomy of the femur may be performed later if remodeling is incomplete. Older children with type I and II fractures are best treated with open reduction and fixation possibly combined with epiphysiodesis of the uninjured distal femur. For patients of all ages who present late after sustaining displaced Salter–Harris type III and IV fractures, open reduction is recommended as soon as possible to restore articular surface.55 Any resultant leg-length discrepancy can be managed in the future. 

Neurovascular Abnormalities

Vascular Injury

Vascular injuries are uncommon with this fracture, with most series reporting no vascular injuries.24,50,71,83 Trauma to the popliteal artery may be caused by trauma from the distal end of the metaphysis and occurs most commonly from fractures caused by forced knee hyperextension resulting in anterior displacement of the epiphysis.10,24,74 In the emergency department, clinical signs of vascular impairment should prompt the surgeon to perform emergency reduction of the fracture. It is our preference to perform the reduction in the operating room but, in situations when a delay of treatment in the operating room is expected, reduction of the gross deformity and splinting of the fracture is a reasonable course of action. Arteriography is not indicted prior to reduction of the fracture. 
In the operating room, the fracture is reduced and stabilized first. If vascular examination is normal after reduction, as evidenced by return of distal pulses, normal capillary refill, and symmetric ankle-brachial indices, the limb is splinted or casted with cut-outs to permit serial evaluation of the pulses easily and the child is admitted for observation. Because intimal injuries of the artery and thrombosis may occur in a delayed fashion, the child's vascular status is monitored closely for 24 hours or so after surgery for signs of worsening vascular status and compartment syndrome. Arteriography is sometimes utilized during the observation period to assess patients with distal perfusion and some abnormality of vascularity, such as diminished pulses, and for those with a worsening of vascular status after reduction and pinning. 
If, after reduction and fixation in the operating room, distal perfusion does not return within 15 to 20 minutes, the time course over which vessel spasm typically recovers, immediate exploration of the vessel by a vascular surgeon is indicated. Although ischemia time may be increased when prolonged fracture stabilization is performed first, manipulation of the fracture after vascular surgery may compromise the repair. Arteriography is indicated only if the fracture has occurred in association with an ipsilateral pelvic fracture or another more proximal leg injury to localize the site of vascular injury or to assist the vascular surgeon in planning the type of repair for those with isolated distal femoral physeal fractures. In most cases, thrombectomy and direct vessel repair or bypass of the injury with a vein graft are necessary to restore flow. If ischemia time exceeds 6 to 8 hours, four-compartment fasciotomies of the lower leg are done in conjunction with the vascular repair to minimize the effects of reperfusion and treat prophylactically compartment syndrome of the calf. 

Peroneal Nerve Injury

The peroneal nerve is the most frequently injured nerve after distal physeal separations.24 It is injured primarily from traction, the result of anteromedial displacement most commonly, but may also be damaged from direct trauma as well. Most peroneal nerve injuries are neurapraxias that spontaneously recover within 6 to 12 weeks of injury.24,80 Persistent neurologic deficit 3 months after fracture warrants electromyographic examination. If the conduction time is prolonged and fibrillation or denervation is present in distal muscles, exploration and microneural reanastomosis or resection of any neuroma may be indicated. Open injuries that result in peroneal nerve transection are best treated with repair or nerve grafting as early as possible after injury based on the child's condition and the status of the soft tissues about the nerve laceration. An ankle-foot orthosis is typically prescribed for patients with peroneal nerve injuries to facilitate rehabilitation and is discontinued after nerve recovery. 

Ligamentous Injuries

Symptomatic knee joint instability has been reported in 8% to 40% of patients with distal femoral physeal fractures.11,24 Although these ligament injuries occur at the time of initial trauma, most are not identified until after the fracture has healed and rehabilitation has been initiated. The anterior cruciate ligament is most commonly disrupted, especially after Salter–Harris type III fractures of the medial femoral condyle.16,54,68,85 Collateral ligament and posterior cruciate ligament disruptions and meniscal injuries may also occur after these fractures but are less common. 
Difficulty with stairs, pain or swelling with activities and episodes of giving way, or knee buckling are typical presenting complaints indicative of knee. The physical examination may identify knee stiffness, signs of ligament instability, and joint line tenderness. Early diagnosis of injuries to the ligaments or menisci can facilitate earlier management11 but, in many cases, the symptoms related to recovery from the fracture make identifying these other injuries difficult. MRI of the knee after healing of the fracture is the best way to delineate these injuries. Meniscal surgery, especially repair, is ideally done soon after fracture healing to facilitate rehabilitation. Knee ligament reconstruction is best done after knee range of motion has been restored and other factors are taken into account including the degree of instability, the child's age, and level of activity. 

Knee Stiffness

Limitation of knee motion after separation of the distal femoral epiphysis is seen in as many as one-third of the patients after fracture healing. This complication is the result of several factors including, intra-articular adhesions, capsular contracture, and muscle contractures, most notably the hamstrings and quadriceps. Initial treatment consists of active and active-assistive range-of-motion exercises. Drop-out casts and dynamic bracing may be of benefit for some with persistent stiffness. For patients with persistent stiffness and loss of functional range of motion despite nonsurgical treatments, surgical interventions may be utilized to restore mobility. Gentle knee manipulation under anesthesia is sometimes useful but is associated with the risk of periarticular fractures of the knee.18 Surgical release of contractures and adhesions, followed by continuous passive motion, is most reliable for regaining motion.77 

Growth Disturbance

The most common complication of distal femoral epiphyseal fractures is growth disturbance. This complication is manifested clinically by the development of angular deformity in cases where the physeal injury is incomplete (Fig. 28-17), shortening of the limb after injuries that result in complete arrest, or, as in some cases, both angulation and limb shortening. In one meta-analysis of case series reported from 1950 to 2007 that included 564 fractures, 52% of fractures resulted in a growth disturbance.7 Although Salter–Harris type I and II fractures in other areas of the body usually have a low risk of growth arrest, these Salter–Harris fractures in the distal femur are also at risk for premature physeal closure (Fig. 28-18). Of the most common Salter–Harris types, growth abnormalities are seen in 36% of type I fractures, 58% of type II fractures, 49% of type III fractures, and 64% of type IV fractures. Displaced distal femoral physeal fractures are four times more likely to develop growth arrest compared to nondisplaced fractures. Growth disturbance is uncommon in patients younger than 2 years of age who sustain these injuries, possibly because of the flat shape of the physis in this age group71 which reduces the damage of physeal cartilage precursor cells. Older children who have more than 2 years of growth remaining are at highest risk for this complication and are most likely to have clinically significant deformities resulting from physeal arrest.71 Although adolescents frequently sustain this fracture and may develop growth complications, the clinical consequences of growth arrest are not as severe, compared to patients between the ages of 2 and 12 years. Increased growth arrest is also seen more commonly in patients who had surgery for these fractures, particularly if transphyseal fixation was utilized.2 
Figure 28-17
An 8-year-old girl struck by a car while on bicycle.
 
Initial AP (A) and lateral (B) radiographs reveal displaced physeal fracture of the distal femur. She underwent closed reduction and pinning (C and D). Four years later she has angular deformity and shortening from asymmetric growth arrest (E and F).
Initial AP (A) and lateral (B) radiographs reveal displaced physeal fracture of the distal femur. She underwent closed reduction and pinning (C and D). Four years later she has angular deformity and shortening from asymmetric growth arrest (E and F).
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Initial AP (A) and lateral (B) radiographs reveal displaced physeal fracture of the distal femur. She underwent closed reduction and pinning (C and D). Four years later she has angular deformity and shortening from asymmetric growth arrest (E and F).
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Figure 28-17
An 8-year-old girl struck by a car while on bicycle.
Initial AP (A) and lateral (B) radiographs reveal displaced physeal fracture of the distal femur. She underwent closed reduction and pinning (C and D). Four years later she has angular deformity and shortening from asymmetric growth arrest (E and F).
Initial AP (A) and lateral (B) radiographs reveal displaced physeal fracture of the distal femur. She underwent closed reduction and pinning (C and D). Four years later she has angular deformity and shortening from asymmetric growth arrest (E and F).
View Original | Slide (.ppt)
Initial AP (A) and lateral (B) radiographs reveal displaced physeal fracture of the distal femur. She underwent closed reduction and pinning (C and D). Four years later she has angular deformity and shortening from asymmetric growth arrest (E and F).
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Figure 28-18
Five-year-old boy hit by car with fracture of the distal femur.
 
A: AP radiograph of minimally displaced Salter–Harris type IV fracture of the distal femur. B: AP radiograph of healed fracture. From this view, it is difficult to determine if injury to the physis has occurred, though a central growth arrest was suspected. C: MRI shows a central growth plate injury probably did occur, although this did not result in formation of a bony bar or growth arrest.
 
(Courtesy of Robert Kay, MD, Los Angeles, CA.)
A: AP radiograph of minimally displaced Salter–Harris type IV fracture of the distal femur. B: AP radiograph of healed fracture. From this view, it is difficult to determine if injury to the physis has occurred, though a central growth arrest was suspected. C: MRI shows a central growth plate injury probably did occur, although this did not result in formation of a bony bar or growth arrest.
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Figure 28-18
Five-year-old boy hit by car with fracture of the distal femur.
A: AP radiograph of minimally displaced Salter–Harris type IV fracture of the distal femur. B: AP radiograph of healed fracture. From this view, it is difficult to determine if injury to the physis has occurred, though a central growth arrest was suspected. C: MRI shows a central growth plate injury probably did occur, although this did not result in formation of a bony bar or growth arrest.
(Courtesy of Robert Kay, MD, Los Angeles, CA.)
A: AP radiograph of minimally displaced Salter–Harris type IV fracture of the distal femur. B: AP radiograph of healed fracture. From this view, it is difficult to determine if injury to the physis has occurred, though a central growth arrest was suspected. C: MRI shows a central growth plate injury probably did occur, although this did not result in formation of a bony bar or growth arrest.
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Diagnosis

Growth arrest is typically evident by 6 months after distal femoral epiphyseal fracture healing. Because the distal femur grows approximately 1 cm a year, complete cessation of growth, or even angular deformity, may not be evident clinically for 12 to 18 months after injury. Subtle radiographic clues may be seen, however, in some cases within 4 to 6 months of injury. Follow-up radiographs after fracture healing should be carefully scrutinized to determine if the physeal line is reconstituted and that Park–Harris growth arrest lines are running parallel to the physis on both AP and lateral views. Growth arrest lines develop when there is a temporary slowing of growth during periods of malnutrition, trauma, chemotherapy, or alcohol consumption, among other things.28,30,60,62 The normal longitudinal orientation of the zone of provisional calcification becomes dense and interconnected, forming a transverse line in the metaphysis. After growth resumes, this dense layer moves away from the physis and is visible on radiographs as a radiodense line of bone in the metaphysis.60 If the line is growing symmetrically away from the physis, then normal growth has resumed. Failure of a Park–Harris line to appear is evidence of premature growth arrest if a line is visible in the comparison radiograph of the uninjured distal femur. An oblique Park–Harris line that converges toward the physis indicates asymmetrical growth caused by a bone bridge across the physis that is preventing growth of one side of the physis. 
Full-length standing x-rays of both lower extremities may also be a clue to help determine if growth disturbance has occurred. It is our practice to obtain standing radiographs of the lower extremities as soon as possible following the initial injury to document the leg-length difference and limb alignment for children at high risk for growth disturbance. Imaging is then repeated at approximately 6-month intervals so that any leg-length difference or change in angulation may be identified. Bilateral lower extremity scanograms and CT scanograms are also useful for measuring leg-length discrepancies but drawbacks compared to full-length radiographs include inability to assess the mechanical axis and increased radiation exposure, respectively.73 If growth disturbance is suspected, MRI or CT is utilized to determine its extent; screw removal is typically done before imaging to improve the quality of imaging by eliminating the scatter effect of the metal. Physeal growth arrest is best detected by fat-suppressed three-dimensional spoiled gradient-recalled echo sequence MRI technique and may identify abnormalities as early as 2 months after injury.22 

Treatment of Physeal Arrest

Progressive Angulation

Early recognition and management of progressive angulation can reduce the need for osteotomy if the diagnosis is made before a clinically significant deformity develops by excising the physeal bar to allow resumption of normal growth. After deformity has developed, however, an osteotomy is generally required whether bar excision is performed or not. The bar is typically located across the portion of the physis that was directly injured. Physeal bars may arise after any fracture type but are most common after type II, III, and IV fractures. When asymmetric growth follows a type II separation, the portion of the physis protected by the Thurston Holland fragment is usually spared, leading to growth inhibition in that portion separated from the metaphyseal fragment. For fractures with a medial metaphyseal spike, the resultant deformity is more likely to be valgus because of lateral growth arrest, whereas the opposite is true for fractures with a lateral metaphyseal spike. For type III and IV fractures, the physeal bar is usually centered on the site of the physis that was traversed by the fracture line. 
Excision is generally recommended for posttraumatic physeal bars that constitute less than 50% of the total cross-sectional area of the distal femoral physis in children with a small degree of angulation and at least 2 years of growth remaining.41,64 In one series, resumption of normal growth was seen in 80% of patients whereas others have reported less stellar results, with growth restoration seen in only 25% to 50% of patients.12,17,31,89 Because bar excision may be unreliable, it is our practice to perform ipsilateral hemiepiphysiodesis combined with contralateral distal femoral epiphysiodesis for patients with less than 15 to 20 degrees of angulation and less than 3 to 4 cm of growth remaining in the injured physis, a scenario most commonly encountered in older children and adolescents with less than 2 years of growth potential. For children with more than 4 cm of growth remaining, physeal bar excision is attempted for those bars that encompass less than 50% of the physis because the combination of ipsilateral hemiepiphysiodesis and contralateral epiphysiodesis results in unacceptable loss of overall height. For older children and adolescents with physeal bars and angulation exceeding 15 to 20 degrees, distal femoral osteotomy may be done at the time of bilateral distal femoral physeal ablation surgery. Physeal bar excision in combination with distal femoral osteotomy may be considered for those younger children who are candidates for bar resection and have angulation that exceeds 15 to 20 degrees.41,43,64 If physeal bar excision fails to restore growth, or limb-length discrepancy is severe at the time of diagnosis of the growth disturbance, limb lengthening and other reconstructive procedures are options to consider based on the projected growth remaining and the limb-length difference. 

Complete Physeal Arrest with Leg-Length Discrepancy

Limb-length discrepancy is a frequently reported complication of distal femoral physeal fractures2,24,37,71,83 but only 22% of patients with distal femoral physeal fractures have leg-length discrepancies measuring greater than 1.5 cm (Fig. 28-19).7 This is the case because many fractures occur in older children and adolescents with limited growth remaining at the time of injury. The treatment strategy varies, depending on the projected amount of discrepancy. Because the decision for treatment must often be made at the time of diagnosis of the complete arrest, methods of predicting the ultimate leg-length discrepancy that do not require serial measurements, such as the Paley or Menelaus methods, are utilized. Immediate contralateral distal femoral epiphysiodesis is indicated for older children and adolescents with projected discrepancies greater than 2 to 2.5 cm. For children with discrepancies that are projected to be larger than 2.5 cm, planning for limb lengthening is initiated. 
Figure 28-19
A 13-year-old male fell off a wall.
 
He sustained a comminuted fracture of the distal femur (A) with superficial abrasions over his leg and underwent closed reduction and fixation with smooth wires (B and C). Eighteen months later he has an LLD of about 2 cm. After a discussion with the family, screw epiphysiodeses of the femur and tibia were done (D). At 1-year follow-up he has nearly equal leg-lengths (E).
He sustained a comminuted fracture of the distal femur (A) with superficial abrasions over his leg and underwent closed reduction and fixation with smooth wires (B and C). Eighteen months later he has an LLD of about 2 cm. After a discussion with the family, screw epiphysiodeses of the femur and tibia were done (D). At 1-year follow-up he has nearly equal leg-lengths (E).
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Figure 28-19
A 13-year-old male fell off a wall.
He sustained a comminuted fracture of the distal femur (A) with superficial abrasions over his leg and underwent closed reduction and fixation with smooth wires (B and C). Eighteen months later he has an LLD of about 2 cm. After a discussion with the family, screw epiphysiodeses of the femur and tibia were done (D). At 1-year follow-up he has nearly equal leg-lengths (E).
He sustained a comminuted fracture of the distal femur (A) with superficial abrasions over his leg and underwent closed reduction and fixation with smooth wires (B and C). Eighteen months later he has an LLD of about 2 cm. After a discussion with the family, screw epiphysiodeses of the femur and tibia were done (D). At 1-year follow-up he has nearly equal leg-lengths (E).
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Summary, Controversies, and Future Directions Related to Fractures of the Distal Femoral Physis

Summary

Physeal fractures of the distal femur, while relatively uncommon, are associated with a higher incidence of complications compared to other physeal fractures. Although the majority are isolated injuries resulting from sports activities and other relatively low-energy mechanisms, some of these fractures are caused by high-energy trauma. Patient evaluation must focus on identifying possible associated injuries and the neurovascular status of the affected limb. Peroneal nerve and popliteal artery injuries, and compartment syndrome of the leg, may occur in association with fractures of the distal femoral physis. Radiographs and CT scan are utilized to fully delineate the fracture pattern and to guide treatment. Most Salter–Harris I and II fractures may be treated with closed reduction and fixation with smooth wires or screws. Salter–Harris III and IV fractures frequently require open reduction and fixation to ensure anatomic alignment of the joint line and physis. Growth disturbance, manifest as angular deformity and leg-length discrepancy, is the most common complication related to distal femoral physeal separations and is seen in approximately half of the patients, especially those who sustain displaced fractures regardless of Salter–Harris type. Other complications of these injuries include knee ligament tears, knee joint stiffness, and neurologic deficits. 

Controversies and Future Directions

Some important issues regarding physeal fractures of the distal femur require clarification and warrant future study. The diagnosis of physeal separations in the face of negative radiographs by stress radiographs of the distal femur remains somewhat controversial. In a past era when open repair of medial collateral ligament injuries were performed, distinguishing physeal separations from ligament tears by stress views was important for making expedient treatment decisions.28 Iatrogenic worsening of physeal injury, however, is a concern when performing this diagnostic test. Now, because initial treatment is similar for both injuries, specifically immobilization and not surgery, and with the increasing use of MRI to evaluate acute knee injuries, stress views are no longer routinely utilized for children and adolescents with possible physeal separations with few exceptions. 
The best method of advanced imaging for displaced fractures is another area of controversy. For intra-articular fractures, some46 have recommended the routine use of CT scan as part of the preoperative evaluation to help delineate the fracture pattern and to plan fixation. Others prefer MRI for these injuries, trading some diminution of bone details for the ability to diagnose chondral, meniscal, and ligament injuries.54,81 In the acute setting, the best choice of imaging studies is unclear. The surgeon must weigh the pros and cons of each modality, taking into consideration, among other concerns, the availability of each of the modalities in the emergency setting, the radiation risk of CT, and familiarity with interpretation of MRI for fracture assessment. Further study is needed. 
Despite advanced imaging methods of fracture evaluation and modern surgical techniques for management of displaced fractures, the fact remains that complications, particularly growth disturbance, are a significant problem associated with these fractures. The future research for this injury, as well as other physeal fractures, must focus on the methods that diminish the incidence of growth disruption and restore growth when arrest occurs. The use of stem cells, cartilage cell regeneration, and other novel techniques are being developed to solve the problem of growth arrest after physeal injury in children.39,69,90 

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