Chapter 26: Fractures and Traumatic Dislocations of the Hip in Children

Ernest L. Sink, Young-Jo Kim

Chapter Outline

Introduction to Hip Fractures

Hip fractures are very common in adults, but are rare in children, comprising less than 1% of all pediatric fractures.11,12,98 Pediatric hip fractures typically result from high-energy mechanisms that can result in other extremity, visceral, or head injuries in 30% of patients, unlike low-energy adult hip fractures common in elderly patients (whose fractures are typically associated with osteoporosis). Occasionally, pediatric hip fractures result from minor trauma superimposed upon bone that is weakened by tumor or metabolic bone disease. These fractures can occur through the physis, but more commonly occur through the femoral neck and the intertrochanteric region. 
The presence of the proximal femoral physis presents many important considerations when treating pediatric femoral neck fractures. Injury to the greater trochanter apophysis following an intertrochanteric fracture can lead to coxa valga.18 Damage to the physis of the femoral neck from fracture, necrosis, or from implant use can result in limb length discrepancies or coxa breva or vara. The surgeon should generally place fixation across the physis in older children with poor bone quality, in adolescents who have little growth potential remaining or if fracture location dictates that adequate fixation must cross the physis. If fixation is not placed across the physis, it may be less stable and the surgeon has to be cognizant how to guide weight-bearing status and provide further immobilization such as a spica cast in younger children. The physis may also be a barrier to any potential interosseous blood supply for the femoral head. Because of this, and the fact that there is little blood supply to the femoral head from the ligamentum teres, an increased risk of necrosis is present following fracture and injury to the important retinacular vessels. 
Although they are less common than other pediatric fractures pediatric hip fractures are important because of the high rate of complications and the potential lifetime morbidity that may result from complications. Potential complications from the fracture and its treatment include chondrolysis, osteonecrosis (ON), varus malunion, nonunion, delayed physiolysis, and growth abnormalities leading to length discrepancy or angular deformities.18 Because the hip is developing in the growing child, deformities can progress and change with age. In addition, review of more recent publications is important because it has been suggested that outcome can be significantly improved if certain treatment principles are consistently followed.11,38,111 

Assessment of Hip Fractures

Mechanisms of Injury for Hip Fractures

Hip fractures in children can be caused by axial loading, torsion, hyperabduction, or a direct blow to the hip. Almost all hip fractures in children are caused by severe, high-energy trauma.6,37,105 Except for the physis, the proximal femur in children is extremely strong, and high-energy forces, such as from motor vehicle accidents and high falls, are necessary to cause fracture.28 If a child suffers a fracture as a result of insignificant trauma, then one should suspect an underlying etiology such as prior injury or surgery,21 metabolic bone disease, or pathologic lesion of the proximal femur (Fig. 26-1). 
Figure 26-1
A 10-year-old boy with a fracture through a unicameral bone cyst sustained while running for a soccer ball.
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Associated Injuries with Hip Fractures

Because these fractures are caused by high-energy trauma, they frequently are accompanied by associated injuries that can affect the patient's overall outcome. Pape et al.,85 in a series of 28 patients with a mean follow-up of 11 years, found favorable outcomes in type II, III, and IV fractures according to Ratliff's criteria.98 Poor functional outcomes were attributed to head trauma, amputation, or peripheral neurologic damage.85 In a series of 14 patients with hip fractures, all of which were caused by vehicular accidents or falls from heights, 12 patients had associated injuries including head and facial injury, other fractures, as well as visceral injury.78 In a series of fractures from high-energy trauma, Bagatur and Zorer5 similarly found associated injuries in 4 of their 17 patients. Infants with hip fractures and without a plausible cause for fracture should be evaluated for nonaccidental trauma by a careful history and an examination of the skin, other extremities, trunk, and head. Further skeletal radiographic imaging is often indicated, and an evaluation by a child protective team is required to diagnose life-threatening head and visceral injuries that can be easily missed in this group. 

Signs and Symptoms of Hip Fractures

The diagnosis of hip fracture in a child is based on the history of high-energy trauma and the typical signs and symptoms of the shortened, externally rotated, and painful lower extremity. Clinical examination is usually obvious, and a patient with a complete fracture is unable to ambulate because of severe pain in the hip and has a shortened, externally rotated extremity. With an incomplete or stress fracture of the femoral neck, the patient may be able to bear weight with a limp and may demonstrate hip or knee pain only with extremes of range of motion, especially internal rotation. An infant with a hip fracture holds the extremity flexed, abducted, and externally rotated. Infants and newborns with limited ossification of the proximal femur can be challenging patients to diagnose with hip fractures as the differential diagnosis can include infection and congenital dislocation of the hip. In the absence of infection symptoms, pseudoparalysis, shortening, and a strong suspicion are the keys to a fracture diagnosis in this age group. 

Imaging and Other Diagnostic Studies for Hip Fractures

A good-quality anteroposterior (AP) pelvic radiograph will provide a comparison view of the opposite hip if a displaced fracture is suspected. For the pelvic radiograph, the leg should be held in extension and in as much internal rotation as possible without causing extreme pain to the patient. A cross-table lateral radiograph should be considered to avoid further displacement and unnecessary discomfort to the patient from an attempt at a frog-leg lateral view. Any break or offset of the bony trabeculae near Ward triangle is an evidence of a nondisplaced or impacted fracture. Nondisplaced fracture or stress fractures may be difficult to detect on radiographs. Special studies may be required to reveal an occult fracture as case examples of further displacement of nondisplaced fracture have been reported.40 Adjunctive studies for stress fracture diagnosis may include a magnetic resonance imaging (MRI), computed tomography (CT) scan, or a technetium bone scan which can demonstrate increased uptake at the fracture site. The typical MRI appearance of a fracture is a linear black line (low signal) on all sequences surrounded by a high-signal band of bone marrow edema and hemorrhage. The low signal represents trabeculae impaction (Fig. 26-2). MRI may detect an occult hip fracture within the first 24 hours after injury.59 In addition, pathologic fractures may require special imaging to aid diagnosis or to fully appreciate bone quality which would impact implant placement. MRI is also a useful test in planning treatment for a pathologic fracture; this test will delineate soft tissues in and around the fracture, which can provide insight into diagnosis and delineate high-yield areas for biopsy. 
Figure 26-2
 
Right hip pain with nondisplaced stress fracture (A). The T1-weighted image shows the impacted cortex (B). The STIR sequence image shows surrounding bony edema (C).
Right hip pain with nondisplaced stress fracture (A). The T1-weighted image shows the impacted cortex (B). The STIR sequence image shows surrounding bony edema (C).
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Figure 26-2
Right hip pain with nondisplaced stress fracture (A). The T1-weighted image shows the impacted cortex (B). The STIR sequence image shows surrounding bony edema (C).
Right hip pain with nondisplaced stress fracture (A). The T1-weighted image shows the impacted cortex (B). The STIR sequence image shows surrounding bony edema (C).
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In infants, an ultrasound can be used to detect epiphyseal separation. In addition, an ultrasound can determine if the patient's epiphysis is located and the presence of an effusion which may be aspirated to confirm diagnosis of sepsis. A bloody aspirate establishes the diagnosis of fracture, whereas a serous or purulent aspirate suggests synovitis or infection, respectively. If performed in the operating room, an aspiration and confirmatory arthrogram of the hip can also be useful, especially if closed reductions and cast immobilization is chosen for the newborn with physiolysis. 
In a patient with posttraumatic hip pain without evidence of a fracture, other diagnoses must be considered, including Perthes disease, synovitis, spontaneous hemarthrosis, and infection. A complete blood count, erythrocyte sedimentation rate, C-reactive protein, and temperature are helpful to evaluate for infection. MRI scan is a useful test to diagnose aseptic ON as a result of Perthes disease or more remote causes of necrosis. In children under 5 years of age, developmental coxa vara can be confused with an old hip fracture.18 

Classification of Hip Fractures

Pediatric hip fractures generally are classified by the method of Delbet (Fig. 26-3).26 This classification system continues to be useful because it is not only descriptive but also has prognostic significance.74 In general, more significant rates of ON and growth arrest are noted in fractures in the proximal end of the femoral neck (type I and type II injuries); whereas lower rates of ON are noted in type III and type IV injuries. Conversely, the latter two groups tend to have higher rates of significant varus malunion if not treated appropriately. Subtrochanteric fractures have been included by some in the discussion of proximal femoral fractures but they are not included in the Delbet classification and are discussed elsewhere. 
Figure 26-3
Delbet classification of hip fractures in children.
 
I, transepiphyseal with (IB) or without (IA) dislocation from the acetabulum; II, transcervical; III, cervicotrochanteric; and IV, intertrochanteric.
I, transepiphyseal with (IB) or without (IA) dislocation from the acetabulum; II, transcervical; III, cervicotrochanteric; and IV, intertrochanteric.
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Figure 26-3
Delbet classification of hip fractures in children.
I, transepiphyseal with (IB) or without (IA) dislocation from the acetabulum; II, transcervical; III, cervicotrochanteric; and IV, intertrochanteric.
I, transepiphyseal with (IB) or without (IA) dislocation from the acetabulum; II, transcervical; III, cervicotrochanteric; and IV, intertrochanteric.
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Type I

Transphyseal fractures occur through the proximal femoral physis, with (type IA) or without (type IB) dislocation of the femoral head from the acetabulum (Fig. 26-4). Such fractures are rare, constituting 8% of femoral neck fractures in children.58 Approximately half of type I fractures are associated with a dislocation of the capital femoral epiphysis. True transphyseal fractures tend to occur in young children after high-energy trauma19,34 and are different from unstable slipped capital femoral epiphysis (SCFE) of the preadolescent, which usually follows a prodromal period of activity-related hip or knee pain. Unstable SCFE differs from traumatic separation as it occurs following minor trauma, which is superimposed on a weakened physis from a combination of multiple factors including obesity and subtle endocrinopathy. 
Figure 26-4
This 2-year-old boy fell on the trampoline and subsequently complained of right hip pain.
 
A: AP radiographs were not grossly abnormal. B: Frog lateral radiograph revealed a transepiphyseal fracture. C, D: Closed reduction in the operating room was stabilized with a percutaneous pin. E: At 8 months, he was asymptomatic and there was no evidence of ON.
A: AP radiographs were not grossly abnormal. B: Frog lateral radiograph revealed a transepiphyseal fracture. C, D: Closed reduction in the operating room was stabilized with a percutaneous pin. E: At 8 months, he was asymptomatic and there was no evidence of ON.
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Figure 26-4
This 2-year-old boy fell on the trampoline and subsequently complained of right hip pain.
A: AP radiographs were not grossly abnormal. B: Frog lateral radiograph revealed a transepiphyseal fracture. C, D: Closed reduction in the operating room was stabilized with a percutaneous pin. E: At 8 months, he was asymptomatic and there was no evidence of ON.
A: AP radiographs were not grossly abnormal. B: Frog lateral radiograph revealed a transepiphyseal fracture. C, D: Closed reduction in the operating room was stabilized with a percutaneous pin. E: At 8 months, he was asymptomatic and there was no evidence of ON.
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Iatrogenic fracture of the physis in children and adolescents may occur during reduction of a hip dislocation (Fig. 26-5).15,55 It is possible that these patients had unrecognized physeal injury at the time of dislocation or, alternatively, the epiphysis may be displaced with vigorous reduction methods. 
Figure 26-5
 
A 16-year old with traumatic right hip dislocation (A). The physis appears intact and a closed reduction was attempted in the OR. Traumatic right physeal separation seen with closed reduction (B).
A 16-year old with traumatic right hip dislocation (A). The physis appears intact and a closed reduction was attempted in the OR. Traumatic right physeal separation seen with closed reduction (B).
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Figure 26-5
A 16-year old with traumatic right hip dislocation (A). The physis appears intact and a closed reduction was attempted in the OR. Traumatic right physeal separation seen with closed reduction (B).
A 16-year old with traumatic right hip dislocation (A). The physis appears intact and a closed reduction was attempted in the OR. Traumatic right physeal separation seen with closed reduction (B).
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Transphyseal fractures without femoral head dislocation have a better prognosis than those with dislocation. Similarly, in children under 2 or 3 years of age, a better prognosis exists than in older children. ON in younger children is unlikely, although coxa vara, coxa breva, and premature physeal closure can cause subsequent leg length discrepancy.18,21 In cases of femoral head dislocation in a type I fracture, the outcome is dismal because of ON and premature physeal closure in virtually 100% of patients.19,34 

Type II

Transcervical fractures are the most common fracture type (45% to 50% of all femoral neck fractures),58 which occur between the physis and are above the intertrochanteric line, and by definition are considered as intracapsular femoral neck fractures. Nondisplaced transcervical fractures have a better prognosis and a lower rate of ON than displaced fractures, regardless of treatment.19,80,98 Necrosis can still occur in minimally displaced fractures, and this may be because of the fact that it is difficult to document how much displacement occurs at the time of trauma. Moon and Mehlman74 performed a meta-analysis of available literature and documented a 28% incidence of ON in type II fractures. The occurrence of ON is thought by these and other investigators to be directly related to fracture displacement, which may lead to disruption or kinking of the blood supply to the femoral head. In addition, the meta-analysis demonstrated higher rates of ON in children older than 10 years at the time of their injury.80 Because the pediatric hip capsule is tough and less likely to tear, some have hypothesized that a possible etiology of vascular impairment in minimally displaced fractures is a result of intra-articular hemarthrosis leading to vessel compression from tamponade.19,58 

Type III

Cervicotrochanteric fractures are, by definition, located at or slightly above the anterior intertrochanteric line and are the second most common type of hip fracture in children, representing about 34% of fractures.58 It is conceivable that a certain portion of these fractures may be intra- and extracapsular as a result of anatomic differences in capsule insertion. Nondisplaced type III fractures also have a much lower complication rate than displaced fractures. Displaced type III fractures are similar to type II fractures in regard to the type of complications that can occur. For instance, the incidence of ON is 18% and is slightly less than in type II fractures80; the risk of ON is directly related to the degree of displacement at the time of injury.14 Premature physeal closure occurs in 25% of patients, and coxa vara can also occur in approximately 14% of patients.58 

Type IV

Intertrochanteric fractures account for only 12% of fractures of the head and neck of the femur in children.58 This fracture is completely extracapsular and has the lowest complication rate of all four types. Nonunion in this fracture is rare, and Moon and Mehlman74 documented a rate of ON of only 5%, which is much lower than in intracapsular fractures. Coxa vara and premature physeal closure have occasionally been reported.19,58,68,97,98 

Unusual Fracture Patterns

Rarely, proximal femoral physiolysis occurs during a difficult delivery and can be confused on radiographs with congenital dislocation of the hip. Type I fracture in a neonate deserves special attention. This injury is exceedingly rare and, because the femoral head is not visible on plain radiographs the diagnosis can be difficult and the index of suspicion must be high. The differential diagnosis includes septic arthritis and hip dislocation. Plain radiographs may show a high-riding proximal femoral metaphysis on the involved side, thus mimicking a congenital hip dislocation. Ultrasonography is useful in diagnosis of neonatal physiolysis; with this test, the cartilaginous head remains in the acetabulum but its dissociation from the femoral shaft can be appreciated. The diagnosis can be missed if there is no history of trauma or if there is an ipsilateral fracture of the femoral shaft.2 In the absence of a known history of significant trauma in a young child, nonaccidental trauma should be ruled out.115 
Stress fractures are caused by repetitive injury and result in hip or knee pain and a limp. Pain associated with long-distance running, marching, or a recent increase in physical activity is suggestive of stress fracture. Close scrutiny of high-quality radiographs may identify sclerosis, cortical thickening, or new bone formation. Undisplaced fractures may appear as faint radiolucencies. If radiographs are inconclusive, adjunctive tests such as MRI, CT, or bone scintigraphy may be helpful. 
An unstable SCFE can be mistaken for a traumatic type I fracture; however, SCFE is caused by an underlying abnormality of the physis and occurs after trivial trauma, usually in preadolescents, whereas type I fractures usually occur in young children. Often in a SCFE there may be signs of remodeling or callous of the femoral metaphysis. 
Fracture after minor trauma suggests weakened bone possibly from systemic disease, tumors, cysts, and infections. If the physical and radiographic evidences of trauma is significant but the history is not consistent, nonaccidental trauma must always be considered.3,115 In the multiply traumatized patient, it is easy to miss hip fractures that are overshadowed by more dramatic or painful injuries. Radiographs of the proximal femur and pelvis are obtained and examined carefully in patients with femoral shaft fractures because ipsilateral fracture or dislocation of the hip is not unusual.2 

Pathoanatomy and Applied Anatomy Relating to Hip Fractures

Ossification of the femur begins in the seventh fetal week.34 In early childhood, only a single proximal femoral chondroepiphysis exists. During the first year of life, the medial portion of this physis grows faster than the lateral, creating an elongated femoral neck by 1 year of age. The capital femoral epiphysis begins to ossify at approximately 4 months in girls and 5 to 6 months in boys. The ossification center of the trochanteric apophysis appears at 4 years in boys and girls.58 The proximal femoral physis is responsible for the metaphyseal growth in the femoral neck, whereas the trochanteric apophysis contributes to the appositional growth of the greater trochanter and less to the metaphyseal growth of the femur.25 Fusion of the proximal femoral and trochanteric physis occurs at about the age of 14 in girls and 16 in boys.52 The confluence of the greater trochanteric physis with the capital femoral physis along the superior femoral neck and the unique vascular supply to the capital femoral epiphysis makes the immature hip vulnerable to growth derangement and subsequent deformity after a fracture (Fig. 26-6). 
Figure 26-6
The transformation of the preplate to separate growth zones for the femoral head and greater trochanter.
 
The diagram shows development of the epiphyseal nucleus. A: Radiograph of the proximal end of the femur of a stillborn girl, weight 325 g. B–E: Drawings made on the basis of radiographs.
 
(Reprinted from Edgren W. Coxa plana. A clinical and radiological investigation with particular reference to the importance of the metaphyseal changes for the final shape of the proximal part of the femur. Acta Orthop Scand Suppl. 1965; 84:1–129, with permission.)
The diagram shows development of the epiphyseal nucleus. A: Radiograph of the proximal end of the femur of a stillborn girl, weight 325 g. B–E: Drawings made on the basis of radiographs.
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Figure 26-6
The transformation of the preplate to separate growth zones for the femoral head and greater trochanter.
The diagram shows development of the epiphyseal nucleus. A: Radiograph of the proximal end of the femur of a stillborn girl, weight 325 g. B–E: Drawings made on the basis of radiographs.
(Reprinted from Edgren W. Coxa plana. A clinical and radiological investigation with particular reference to the importance of the metaphyseal changes for the final shape of the proximal part of the femur. Acta Orthop Scand Suppl. 1965; 84:1–129, with permission.)
The diagram shows development of the epiphyseal nucleus. A: Radiograph of the proximal end of the femur of a stillborn girl, weight 325 g. B–E: Drawings made on the basis of radiographs.
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Vascular Anatomy

Because of the frequency and sequelae of ON of the hip in children, the blood supply has been studied extensively.24,50,57,89 Postmortem injection and microangiographic studies have provided clues to the vascular changes with age. These observations are as follows. 
  •  
    At birth, interosseous continuation of branches of the medial and lateral circumflex arteries (metaphyseal vessels) traversing the femoral neck predominately supply the femoral head. These arteries gradually diminish in size as the cartilaginous physis develops and forms a barrier thus preventing transphyseal continuity of these vessels into the femoral head. Thus metaphyseal blood supply to the femoral head is virtually nonexistent by age 4.
  •  
    When the metaphyseal vessels diminish, the intracapsular lateral epiphyseal vessels predominate and the femoral head is primarily supplied by these vessels, which extend superiorly on the exterior of the neck, bypassing the physeal barrier and then continuing into the epiphysis.
  •  
    Ogden83 noted that the lateral epiphyseal vessels consist of two branches: The posterosuperior and posteroinferior branches of the medial circumflex artery. At the level of the intertrochanteric groove, the medial circumflex artery branches into a retinacular arterial system (the posterosuperior and posteroinferior arteries). These arteries penetrate the capsule and traverse proximally (covered by the retinacular folds) along the neck of the femur to supply the femoral head peripherally and proximally to the physis. The posteroinferior and posterosuperior arteries persist throughout life and supply the femoral head. At about 3 to 4 years of age, the lateral posterosuperior vessels appear to predominate and supply the entire anterior lateral portion of the capital femoral epiphysis.
  •  
    The vessels of the ligamentum teres are of virtually no importance. They contribute little blood supply to the femoral head until age 8, and then only about 20% as an adult.
The above information has clinical importance. For instance, the multiple small vessels of the young coalesce with age to a limited number of larger vessels. As a result, damage to a single vessel can have serious consequences; for example, occlusion of the posterosuperior branch of the medial circumflex artery can cause ON of the anterior lateral portion of the femoral head.18 
It is also important for surgeons to recognize where capsulotomy should be performed to decrease iatrogenic injury to existing blood supply. It is suspected that anterior capsulotomy does not damage the blood supply to the femoral head as long as the intertrochanteric notch and the superior lateral ascending cervical vessels are avoided. 

Soft Tissue Anatomy

The hip joint is enclosed by a thick fibrous capsule that is considered less likely to tear than in adult hip fractures. Bleeding within an intact capsule may lead to a tense hemarthrosis after intracapsular fracture which can theoretically tamponade the ascending cervical vessels and may have implications in the development of ON. The hip joint is surrounded on all sides by a protective cuff of musculature; as such, open hip fracture is rare. In the absence of associated hip dislocation, neurovascular injuries are rare. 
The sciatic nerve emerges from the sciatic notch beneath the piriformis and courses superficial to the external rotators and the quadratus medial to the greater trochanter. The lateral femoral cutaneous nerve lies in the interval between the tensor and sartorius muscles and supplies sensation to the lateral thigh. This nerve must be identified and preserved during an anterolateral approach to the hip. The femoral neurovascular bundle is separated from the anterior hip joint by the iliopsoas. Thus, any retractor placed on the anterior acetabular rim should be carefully placed deep to the iliopsoas to protect the femoral bundle. Inferior and medial to the hip capsule, coursing from the deep femoral artery toward the posterior hip joint, is the medial femoral circumflex artery. Placement of a distal Hohmann retractor too deeply can tear this artery, and control of the bleeding may be difficult. 

Treatment Options for Hip Fractures

Rationale for Management

Much of the early, classic literature on hip fractures in children documented high rates of coxa vara, delayed union, and nonunion in patients treated without internal fixation.68,98 Canale and Bourland18 noted that fractures treated by spica casting alone had a greater incidence of coxa vara. They attributed a lower rate of coxa vara and nonunion in some of their patients to the use of internal fixation for all transcervical fractures.19 More recent literature supports the concept that attempted conservative treatment can result in unacceptably high rates of coxa vara.6 These high rates of complications may be because of an underappreciation of the uniqueness of this injury and its requisite necessity for operative treatment in most patients, which is in contrast to other pediatric injuries.6 Subsequent authors have documented lower rates of ON, coxa vara, and nonunion in patients who were aggressively treated with anatomic reduction (open or closed) and internal fixation (with or without supplemental casting) within 24 hours of injury.5,22,37,82,87,105 A recent paper of 36 patients followed until healing concluded that patients treated with open reduction had a smaller complication rate and recommended open reduction and internal fixation (ORIF) over closed reduction and internal fixation (CRIF) whenever possible.7 Therefore, contemporary management is directed at early, anatomic reduction of these fractures with stable internal fixation and selective use of supplemental external stabilization (casting), with the goal of minimizing devastating late complications.22,98,111 

Nonoperative Treatment of Hip Fractures

Indications/Contraindications (Table 26-1)

 
Table 26-1
Hip Fractures
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Table 26-1
Hip Fractures
Nonoperative Treatment
Indications Relative Contraindications
Infants and toddlers 0–2 y with stable minimally displaced type I fractures Type I fractures >2 y
Nondisplaced type II and III fractures in younger children (0–5 y) Displaced fractures
Nondisplaced stress fractures Older children (>5 y with type II and III) fractures
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Techniques

Nonoperative treatment in children less than 1 year may be either a Pavlik harness or abduction brace. In older children treated non-op a spica cast past the knee may be considered. There are no outcome studies on spica or brace treatment but a spica cast should only be considered in younger children up to 5 years with nondisplaced fractures. Non-operative and spica cast treatment alone is not optimal in older children as the potential for nonunion is to great not to perform internal fixation. A supplemental spica cast is recommended for children that are not near skeletal maturity secondary to the fact that internal fixation will often stop distal to the epiphyseal physis. 

Operative Treatment of Hip Fractures

Indications/Contraindications for Surgical Versus Nonsurgical Treatment

Internal fixation is indicated in children with displaced femoral neck fractures. Internal fixation is also recommended for most acute nondisplaced fractures except in children where size limits the effect of internal fixation (0 to 5 years). Completely nondisplaced fractures may have percutaneous screw placement with or without capsulotomy. If there is any residual displacement after an attempted closed reduction, an open reduction should be performed. The threshold for open reduction should be any displacement to decrease the incidence of ON and nonunion. 

The Watson-Jones Approach (Anterior Lateral Approach)

Preoperative Planning (Table 26-2)
 
Table 26-2
Watson-Jones Approach
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Table 26-2
Watson-Jones Approach
Preoperative Planning Checklist
  •  
    OR table: Fracture table/flattop table to allow adequate imaging
  •  
    Position/positioning aids: The patient should have a bump on the back and posterior pelvis to allow access to the region posterior to the greater trochanter
  •  
    Fluoroscopy location: On the side opposite the operative field. If percutaneous fixation is indicated a two C-arm technique may be helpful
  •  
    Equipment: Deep retractors
  •  
    Tourniquet (sterile/nonsterile): NA
  •  
    Etc:
X
Surgical Approach
If open reduction is necessary, the Watson-Jones approach is a useful and direct approach to the femoral neck. A lateral incision is made over the proximal femur, slightly anterior to the greater trochanter (Fig. 26-7A). The fascia lata is incised longitudinally (Fig. 26-7B). The innervation of the tensor muscle by the superior gluteal nerve is 2 to 5 cm above the greater trochanter, and care should be taken not to damage this structure. The tensor muscle is reflected anteriorly. The interval between the gluteus medius and the tensor muscles will be used (Fig. 26-7C). The plane is developed between the muscles and the underlying hip capsule (Fig. 26-7D). If necessary, the anterior-most fibers of the gluteus medius tendon can be detached from the trochanter for wider exposure. After clearing the anterior hip capsule, longitudinal capsulotomy is made along the anterosuperior femoral neck. A transverse incision can be added superiorly for wider exposure (Fig. 26-7E). Once the hip fracture is reduced, guidewires for cannulated screws can be passed perpendicular to the fracture along the femoral neck from the base of the greater trochanter. 
Figure 26-7
Watson-Jones lateral approach to the hip joint for open reduction of femoral neck fractures in children.
 
A: Skin incision. B: Incision of the fascia lata between the tensor muscle (anterior) and gluteus maximus (posterior). C: Exposure of the interval between the gluteus medius and tensor fascia lata (retracted anteriorly). Development of the interval will reveal the underlying hip capsule. D: Exposure of the hip capsule. E: Exposure of the femoral neck after T incision of the capsule.
A: Skin incision. B: Incision of the fascia lata between the tensor muscle (anterior) and gluteus maximus (posterior). C: Exposure of the interval between the gluteus medius and tensor fascia lata (retracted anteriorly). Development of the interval will reveal the underlying hip capsule. D: Exposure of the hip capsule. E: Exposure of the femoral neck after T incision of the capsule.
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Figure 26-7
Watson-Jones lateral approach to the hip joint for open reduction of femoral neck fractures in children.
A: Skin incision. B: Incision of the fascia lata between the tensor muscle (anterior) and gluteus maximus (posterior). C: Exposure of the interval between the gluteus medius and tensor fascia lata (retracted anteriorly). Development of the interval will reveal the underlying hip capsule. D: Exposure of the hip capsule. E: Exposure of the femoral neck after T incision of the capsule.
A: Skin incision. B: Incision of the fascia lata between the tensor muscle (anterior) and gluteus maximus (posterior). C: Exposure of the interval between the gluteus medius and tensor fascia lata (retracted anteriorly). Development of the interval will reveal the underlying hip capsule. D: Exposure of the hip capsule. E: Exposure of the femoral neck after T incision of the capsule.
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The Smith-Peterson Approach (Anterior Approach)

Preoperative Planning (Table 26-3)
 
Table 26-3
Smith-Petersen Approach
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Table 26-3
Smith-Petersen Approach
Preoperative Planning Checklist
  •  
    OR table: Radiolucent
  •  
    Position/positioning aids: A “bump” under the thoracolumbar spine to the posterior-superior iliac spine to access the greater trochanter for screw insertion
  •  
    Fluoroscopy location: Opposite surgeon
  •  
    Equipment: Long retractors
  •  
    Tourniquet (sterile/nonsterile): NA
  •  
    Etc:
X
Surgical Approach
A longitudinal incision distal and lateral to the anterior-superior iliac spine or bikini approach can be used through the Smith-Petersen interval (Fig. 26-8). Care should be taken to identify and protect the lateral femoral cutaneous nerve. The fascia over the tensor fascia muscle is opened longitudinally. Blunt dissection is then done to expose the medial aspect of the muscle as far proximal as the iliac crest. The rectus muscle is seen and the lateral fascia of the rectus is incised and the rectus can then be retracted in a medial direction. The fascia on the floor of the rectus is incised longitudinally and the lateral iliopsoas is elevated off the hip capsule in a medial direction to expose the hip capsule. The sartorius and rectus muscles can be detached for greater exposure of the hip capsule if required. Medial and inferior retractors should be carefully placed around the femoral neck once the capsule is incised to avoid damage to the femoral neurovascular bundle and medial femoral circumflex artery, respectively. Care must be taken not to violate the intertrochanteric notch and the lateral ascending vessels. Because the lateral aspect of the greater trochanter is not exposed, wires must be passed percutaneously once the hip fracture is reduced. 
Figure 26-8
Smith-Petersen anterolateral approach to the hip joint.
 
A: Skin incision. Incision is 1 cm below the iliac crest and extends just medial to the anterior-superior iliac spine. B: Skin is retracted, exposing the fascia overlying the anterior-superior iliac spine. The interval between the sartorius and the tensor fascia lata is identifiable by palpation. C: The sartorius is detached from the anterior-superior iliac spine. Splitting of the iliac crest apophysis and detachment of the rectus femoris (shown attached to anterior-inferior iliac spine) will facilitate exposure of the hip capsule. D: The hip capsule is exposed. A T incision is made to reveal the femoral head and neck.
A: Skin incision. Incision is 1 cm below the iliac crest and extends just medial to the anterior-superior iliac spine. B: Skin is retracted, exposing the fascia overlying the anterior-superior iliac spine. The interval between the sartorius and the tensor fascia lata is identifiable by palpation. C: The sartorius is detached from the anterior-superior iliac spine. Splitting of the iliac crest apophysis and detachment of the rectus femoris (shown attached to anterior-inferior iliac spine) will facilitate exposure of the hip capsule. D: The hip capsule is exposed. A T incision is made to reveal the femoral head and neck.
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Figure 26-8
Smith-Petersen anterolateral approach to the hip joint.
A: Skin incision. Incision is 1 cm below the iliac crest and extends just medial to the anterior-superior iliac spine. B: Skin is retracted, exposing the fascia overlying the anterior-superior iliac spine. The interval between the sartorius and the tensor fascia lata is identifiable by palpation. C: The sartorius is detached from the anterior-superior iliac spine. Splitting of the iliac crest apophysis and detachment of the rectus femoris (shown attached to anterior-inferior iliac spine) will facilitate exposure of the hip capsule. D: The hip capsule is exposed. A T incision is made to reveal the femoral head and neck.
A: Skin incision. Incision is 1 cm below the iliac crest and extends just medial to the anterior-superior iliac spine. B: Skin is retracted, exposing the fascia overlying the anterior-superior iliac spine. The interval between the sartorius and the tensor fascia lata is identifiable by palpation. C: The sartorius is detached from the anterior-superior iliac spine. Splitting of the iliac crest apophysis and detachment of the rectus femoris (shown attached to anterior-inferior iliac spine) will facilitate exposure of the hip capsule. D: The hip capsule is exposed. A T incision is made to reveal the femoral head and neck.
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Lateral Approach for Decompression
In many cases, an adequate closed reduction can be obtained thus avoiding the need to open the hip joint for reduction purposes. However, the surgeon may decide to perform a capsulotomy to decompress the hip joint. The authors prefer to do this from a lateral approach. With this method, a 4-cm incision is made distal and lateral to the greater trochanter. From this incision, the fascia lata is incised and guide pins for cannulated screws are placed and screws are inserted in the standard manner. The anterior fibers of the gluteus medius are elevated allowing incision of the anterior capsule with a Cobb elevator, knife, or osteotome. 

Surgical Dislocation of the Hip

Preoperative Planning (Table 26-4)
 
Table 26-4
Surgical Dislocation of the Hip
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Table 26-4
Surgical Dislocation of the Hip
Preoperative Planning Checklist
  •  
    OR table: Radiolucent
  •  
    Position/positioning aids: Patients are positioned in the lateral position. This can be accomplished with a pegboard, beanbag, or other available positioning devices.
  •  
    Fluoroscopy location: Opposite the surgeon
  •  
    Equipment: Curved scissors are needed if the ligamentum teres is to be transected for dislocation. A saw is needed for the greater trochanteric osteotomy
  •  
    Tourniquet (sterile/nonsterile): NA
X
Positioning
Patients are positioned in the lateral position on a radiolucent table. The opposite leg should be well padded so there is no pressure on the peroneal nerve. An axillary roll is needed and both upper extremities should be carefully positioned to avoid any pressure or tension on the upper extremity and brachial plexus. The complete left hip and leg is draped free as high as the iliac crest. 
Surgical Approach
The technique was originally described by Ganz et al.39 A lateral incision is performed centered on the anterior third of the greater trochanter. The proximal extent of the incision is at least at the midpoint between the greater trochanter and the iliac crest. The tensor fascia is incised in the anterior third of the greater trochanter and along the anterior border of the gluteus maximus muscle. This is known as the Gibson modification79 which protects the neurovascular bundle of the gluteus maximus. This exposes the upper vastus lateralis, gluteus medius, and greater trochanter. The leg is positioned with the hip in slight extension and internal rotation to better visualize the anatomic landmarks for this portion of the approach. The piriformis tendon is visualized deep to the posterior/distal aspect of gluteus medius. Once exposed the tendon can be slightly retracted distal to expose the inferior margin of the gluteus minimus fascia. The inferior fascia of the minimus is opened to allow the muscle to be retracted in an anterior-superior direction off the hip capsule. It is easier to visualize this interval prior to the trochanteric osteotomy. A greater trochanteric osteotomy is performed from anterior to the tip of the greater trochanter to the posterior border of the vastus lateralis ridge. The width of the osteotomy is approximately 10 to 15 mm in children. A muscular flap including the gluteus minimus, gluteus medius, osteotomized greater trochanter, vastus lateralis, and vastus intermedius is elevated sharply off the hip capsule in an anterior/superior direction. Flexion and external rotation of the operative hip will facilitate the muscle dissection. The dissection is all anterior to the piriformis tendon the majority of which should be still attached to the trochanter (not the osteotomized fragment). Keeping the piriformis tendon intact with dissection anterior to the tendon protects the retinacular branch of the medial circumflex artery. The capsule should be visualized as anterior as the medial region of the indirect tendon. 
The hip capsule is then opened in a “z”-shaped fashion. The longitudinal limb is along the axis of the femoral neck in line with the iliofemoral ligament. The distal aspect is proximal but in line with the intertrochanteric ridge. The posterior limb of the capsule is opened in the capsular recess of the acetabulum as far posterior as the piriformis tendon. Therefore, the lateral and posterior capsular flap is created that protects the retinaculum as it pierces the hip capsule. Once the capsule is opened the anatomy and fracture can be visualized. If hip dislocation is indicated the leg is flexed and externally rotated and placed in a sterile leg bag. The hip is subluxated with a bone hook and curved large scissors are used to transect the ligamentum teres. 
The location of the hip fracture will dictate the next step after the capsulotomy. If dislocation is warranted temporary fixation of the fracture with a threaded Kirschner wire (K-wire) is recommended for safe dislocation. Without temporary fixation damage may occur to the retinaculum that is easily visualized in the lateral and posterolateral region of the femoral neck. 
After fracture fixation the hip capsule is loosely approximated. The greater trochanter is reduced and fixation with 2 to 3 screws (3.5 mm) is performed. Weight-bearing restrictions are dependent on the fracture type. 
Current Treatment Options
Type I
Fracture treatment is based on the age of the child, presence of femoral head dislocation, and fracture stability after reduction. In toddlers under 2 years of age with nondisplaced or minimally displaced fractures, simple spica cast immobilization is likely to be successful. Because the fracture tends to displace into varus and external rotation, the limb should be casted in mild abduction and neutral rotation to prevent displacement. Close follow-up in the early postinjury period is critical. Displaced fractures in toddlers should be reduced closed by gentle traction, abduction, and internal rotation. If the fracture “locks on” and is stable, casting without fixation is indicated. If casting without fixation is done, repeat radiographs should be taken within days to look for displacement because the likelihood of successful repeat reduction decreases rapidly with time and healing in a young child. 
If the fracture is not stable, it should be fixed with small-diameter (2-mm) smooth pins that cross the femoral neck and into the epiphysis. Use of smooth pins will theoretically decrease risk of physis injury in younger patients with a transphyseal fracture. An arthrogram after reduction and stabilization of the fracture may be indicated to insure alignment is anatomic. An arthrogram prior to reduction and pinning may obscure bony detail and hinder assessment during reduction. 
Children older than 2 years should have operative fixation, even if the fracture is nondisplaced; because the complications of late displacement may be great, fixation should cross the physis into the capital femoral epiphysis. Smooth pins can be used in young children, but cannulated screws are better for older, larger children and adolescents. In this older group (>10 years) the effect of eventual limb length discrepancy is small and is a reasonable tradeoff for the superior fixation and stabilization needed to avoid complications in larger and older children. 
Closed reduction of type IB fracture-dislocations may be attempted, but immediate open reduction is necessary if a single attempt at closed reduction is unsuccessful. Internal fixation is mandatory. The surgical approach should be from the side to which the head is dislocated, generally posterolateral. Parents must be advised in advance about the risk of ON. 
Postoperative spica cast immobilization is mandatory in all but the oldest and most reliable adolescents who have large-threaded screws crossing the physis. Fixation may be removed shortly after fracture healing to enable further growth in patients. 
Type II and Type III
Intracapsular femoral neck fractures mandate anatomic reduction and, in most cases, internal fixation. In rare cases, children under 5 years of age with nondisplaced and completely stable type II and cervicotrochanteric fractures can be managed with spica casting and close follow-up to detect varus displacement in the cast.29,58,68 However, in almost all cases, internal fixation is recommended by most investigators for nondisplaced transcervical fractures40,58 because the risk of late displacement in such fractures far outweighs the risk of percutaneous screw fixation, especially in young children.16 
Displaced neck fractures should be treated with anatomic reduction and stable internal fixation to minimize the risk of late complications. Coxa vara and nonunion were frequent in several large series of displaced transcervical fractures treated with immobilization but without internal fixation.6,19,68 However, when an anatomic closed or ORIF was used, the rates of these complications were much lower.19,37,82,111 
Gentle closed reduction of displaced fractures is accomplished with the use of longitudinal traction, abduction, and internal rotation. Open reduction frequently is necessary for displaced fractures and should be done through a Watson-Jones surgical approach. 
Internal fixation with cannulated screws is done through a small lateral incision with planned entry above the level of the lesser trochanter. Two to three screws should be placed; if possible, the most inferior screw will skirt along the calcar with the remaining screws spaced as widely as possible.15 Usually, the small size of the child's femoral neck will accommodate only two screws. Care should be taken to minimize unnecessary drill holes in the subtrochanteric region because they increase the risk of subtrochanteric fracture. 
In type II fractures, physeal penetration may be necessary for purchase58,82; the sequelae of premature physeal closure and trochanteric overgrowth are much less than those of nonunion, pin breakage, and ON. Treatment of the fracture is the first priority, and any subsequent growth disturbance and leg length discrepancy are secondary. Consideration may be given to simultaneous capsulotomy or aspiration of the joint to eliminate pressure from a hemarthrosis at the time of surgery. 
Displaced cervicotrochanteric fractures have been shown to have a complication rate similar to that for type II fractures and should be treated similarly. If possible, screws should be inserted short of the physis in type III fractures. Fixation generally does not need to cross the physis in type III fractures. Alternatively, a pediatric hip compression screw or a pediatric locking hip plate62,102 can be used for more secure fixation of distal cervicotrochanteric fractures in a child over 5 years of age particularly if there is a smaller region for screw purchase lateral and distal to the fracture. Spica casting is routine in most type II and III fractures, except in older children where the screws can cross the physis.37 
Type IV
Good results can be obtained after closed treatment of most intertrochanteric fractures in younger children, regardless of displacement. Traction and spica cast immobilization are effective.15 Instability or failure to maintain adequate reduction and polytrauma are indications for internal fixation. Older children (>10 years) or those with significant displacement can be treated with ORIF (Fig. 26-9). A pediatric hip screw or pediatric hip locking plate provides the most rigid internal fixation for this purpose. Smaller hip screw devices have made ORIF an option in children younger than 10 years. This may avoid the period of spica cast treatment and a more anatomic alignment. 
Figure 26-9
 
A: A 14-year-old boy who fell from a tree swing sustained this nondisplaced left intertrochanteric hip fracture. B: Lateral radiograph shows the long spiral fracture. C: Three months after fixation with an adult sliding hip screw.
A: A 14-year-old boy who fell from a tree swing sustained this nondisplaced left intertrochanteric hip fracture. B: Lateral radiograph shows the long spiral fracture. C: Three months after fixation with an adult sliding hip screw.
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Figure 26-9
A: A 14-year-old boy who fell from a tree swing sustained this nondisplaced left intertrochanteric hip fracture. B: Lateral radiograph shows the long spiral fracture. C: Three months after fixation with an adult sliding hip screw.
A: A 14-year-old boy who fell from a tree swing sustained this nondisplaced left intertrochanteric hip fracture. B: Lateral radiograph shows the long spiral fracture. C: Three months after fixation with an adult sliding hip screw.
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Author's Preferred Treatment for Hip Fractures

Type I

Nondisplaced or minimally displaced stable fractures in toddlers up to age 2 should be treated in a spica cast without internal fixation. The limb should be casted in a position of abduction and neutral rotation to prevent displacement into varus. If the fracture requires reduction or moves significantly during reduction or casting maneuvers, then internal fixation is mandatory. Two-millimeter smooth K-wires are inserted percutaneously to cross the physis. We recommend two or three wires. Wires should be cut off and bent below the skin for retrieval under a brief general anesthetic when the fractures healed. We do not recommend leaving the wires outside the skin. Frequent radiographs are necessary to check for migration of the pins into the joint space. A spica cast is always applied in this age group and should remain in place for at least 6 weeks.37 Even if type I fractures in children older than 2 years are anatomically reduced, these patients should always have stabilization with internal fixation. While K-wires are appropriate for small children, 4- to 7.3-mm cannulated screws crossing the physis can be considered in older, larger children after closed reduction. Fluoroscopically placing a guide pin across the femoral head and neck allows one to locate the proper site for a small incision overlying the lateral femur in line with the femoral neck. Two guide pins are placed into the epiphysis, and the wires are overdrilled to the level of the physis (but not across to avoid growth arrest as much as possible). The hard metaphysis and lateral femoral cortex are tapped (in contrast to elderly patients with osteoporosis) to the level of the physis and stainless steel screws are placed. 
If gentle closed reduction cannot be achieved, an open approach is preferred for type IA fractures. For type IB fractures, the choice of approach is dictated by the position of the femoral epiphysis. If it is anterior or inferior, a Watson-Jones approach should be used. On the other hand, most type IB fractures are displaced posteriorly, in which case a posterior approach should be selected. A surgical dislocation approach may also be used to give complete visualization of the hip and retinacular vessels. Under direct vision, the fracture is reduced and guidewires are passed from the lateral aspect of the proximal femur up the neck perpendicular to the fracture; predrilling and tapping are necessary before the insertion of screws. All children are immobilized in a spica cast. 
Older children and adolescents will usually require similar reduction methods on a fracture table, and the fracture is stabilized after closed or, if needed, open reduction. Larger 6.5- or 7.3-mm screws are needed and are placed after predrilling and tapping over the guide pins. Through a lateral incision, the screws are placed, and an anterior capsulotomy is performed. Such stout fixation usually obviates the need for spica casting in an adolescent but, if future patient compliance or fracture stability is in doubt, a spica cast is used. The lateral position is utilized for the surgical dislocation approach. The fracture can be reduced without the need for a traction table in the surgical dislocation approach. 

Types II and III

In all cases, we attempt a closed reduction. It is critical that the fracture be reduced anatomically to decrease the potential of nonunion and AVN. If unsuccessful, a reduction can be performed through a Watson-Jones approach because it provides direct exposure of the femoral neck for gentle fracture reduction. If there is experience with the surgical dislocation approach this will give the surgeon visualization for fracture reduction and fixation. Both approaches allow the fracture to be anatomically reduced under direct vision. Once the fracture is visualized and anatomically reduced, guidewires are then placed up the femoral neck perpendicular to the fracture. If possible, penetration of the physis should be avoided.21,36 However, in most unstable type II fractures, penetration of the physis may be necessary to achieve stability and avoid the complications associated with late displacement.15,82 Good fixation of type III fractures generally is possible without penetration of the physis. With the surgical dislocation approach, the reduction can usually be performed without dislocation of the femoral head. If femoral head dislocation is required the fracture and femoral head should be provisionally reduced and fixed prior to subluxation and transecting the ligamentum teres to prevent traction on the retinaculum with the dislocation. Once dislocated a guidewire can be placed retrograde through the fovea. 
Type II and III fractures should be stabilized with 4- to 4.5-mm cannulated screws in small children up to age 8. After the age of 8, fixation with 6.5-mm cannulated screws is appropriate. Two or three appropriately sized screws should be used, depending on the size of the child's femoral neck. As in type I fractures, we recommend placing at least two guide pins, and predrilling and tapping of the femoral neck is necessary to avoid displacement of the fracture while advancing the screws. Finally, we believe that if the physis is not crossed with implants, supplementary spica casting is needed to prevent malunion or nonunion. 

Type IV

Undisplaced type IV fractures in children younger than 3 to 4 years are treated without internal fixation with immobilization in a spica cast for 12 weeks. Great care is needed to cast the limb in a position that best aligns the bone (Fig. 26-10A, B). Frequent radiographic examination is necessary to assess for late displacement, particularly into varus. In some cases, it may be difficult to assess reduction in a spica cast so that alternative testing such as a limited CT scan may be useful to compare to intraoperative positioning (Fig. 26-10 C, D). Displaced type IV fractures in all children more than 3 years should be treated with internal fixation with a pediatric or juvenile compression hip screw or pediatric locking hip plate placed into femoral neck short of the physis. It is important to place an antirotation wire before drilling and tapping the neck for the dynamic hip screw. Closed reduction often is possible with a combination of traction and internal rotation of the limb. If open reduction is necessary, a lateral approach with anterior extension to close reduce the fracture is preferred. 
Figure 26-10
 
A: A 4-year-old boy fell from his window, causing a displaced type IV fracture. B: Positioning of the hip in a spica cast is usually in hip flexion and confirmed under fluoroscopy. C: Fluoroscopic radiographs in 90 degrees of hip flexion insure anatomic correctness. D: At 1-week follow-up, radiographs were inconclusive; a CT scan assists in confirming location.
A: A 4-year-old boy fell from his window, causing a displaced type IV fracture. B: Positioning of the hip in a spica cast is usually in hip flexion and confirmed under fluoroscopy. C: Fluoroscopic radiographs in 90 degrees of hip flexion insure anatomic correctness. D: At 1-week follow-up, radiographs were inconclusive; a CT scan assists in confirming location.
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Figure 26-10
A: A 4-year-old boy fell from his window, causing a displaced type IV fracture. B: Positioning of the hip in a spica cast is usually in hip flexion and confirmed under fluoroscopy. C: Fluoroscopic radiographs in 90 degrees of hip flexion insure anatomic correctness. D: At 1-week follow-up, radiographs were inconclusive; a CT scan assists in confirming location.
A: A 4-year-old boy fell from his window, causing a displaced type IV fracture. B: Positioning of the hip in a spica cast is usually in hip flexion and confirmed under fluoroscopy. C: Fluoroscopic radiographs in 90 degrees of hip flexion insure anatomic correctness. D: At 1-week follow-up, radiographs were inconclusive; a CT scan assists in confirming location.
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Postoperative Care

In general, we believe supplementary casting should be considered for the majority of patients with proximal femoral fractures. For instance, casting is indicated in all type I fractures except in the rare adolescents who have been treated with two to three large screws that cross the physis and who will be obviously compliant with restricted weight bearing. For type II and III fractures, we recommend a hip spica cast to be used for at least 6 weeks in all patients whose implants do not cross the femoral physis. This recommendation makes sense when one considers that in children younger than 10, we try to avoid crossing the physis, and these patients usually do well with these casts. On the other hand, children older than 12 years can be treated with transphyseal fixation that will be stable enough to avoid cast fixation and which coincidently also tends to be poorly tolerated in this age group. For children 10 to 12 years, the use of a postoperative cast depends on the stability of fracture fixation and the patient's compliance; if either is in doubt, a single hip spica cast is used. 
Type IV fractures treated with a hip screw and side plate do not require cast immobilization. Formal rehabilitation usually is unnecessary unless there is a severe persistent limp, which may be due to abductor weakness. Stiffness is rarely a problem in the absence of ON. 

Potential Pitfalls and Preventative Measures (Table 26-5)

 
Table 26-5
Hip Fractures
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Table 26-5
Hip Fractures
Potential Pitfalls and Prevention
Pitfalls Preventions
Pitfall #1: Nonunion Prevention 1a: Anatomic reduction, open the fracture site if necessary
Prevention 1b: Stable internal fixation, cross the physis if necessary
Prevention 1c: Spica cast supplemental immobilization for children <10 or 10–12 if there is a concern for stabilization
Pitfall #2: Avascular necrosis Prevention 2a: Urgent reduction >24 hrs
Prevention 2b: Open reduction or capsulotomy if reduction is closed
Prevention 2c: Anatomic reduction
Pitfall #3: Physeal arrest Prevention 3a: Stop the fixation distal to the physis but do not compromise stability. The majority of type III and IV fractures can achieve stable fixation without crossing the physis.
Prevention 3b: If the stability of fracture fixation is not enough with implants distal to the physis the surgeon must cross the physis.
Prevention 3c: Consider removal of implants once the fracture has bony union.
X

Summary of Key Points

  •  
    For young, small patients, the operation should be done on a radiolucent operating table rather than on a fracture table, which is more appropriate for older and larger adolescents.
  •  
    Because the femoral bone in children is harder than the osteoporotic bone in elderly patients, predrilling and pretapping are necessary for insertion of all screws.
  •  
    Multiple attempts at wire placement should be avoided because they result in empty holes in the subtrochanteric region of the femur. This predisposes to late subtrochanteric fracture below or at the level of the screw heads after removal of the spica cast.
  •  
    A hip spica cast must be used to supplement internal fixation in all patients who are younger than 10 years. For older patients, if the stability of the fracture is questionable or if the child's compliance is doubtful, the surgeon should not hesitate to apply a hip spica cast. The quality of reduction and the stability of the fixation have a direct impact on the occurrence of nonunion.37,68,82,98
  •  
    Growth of the femur and the contribution of the proximal femoral physis are important; however, this physeal contribution to growth is only 13% of the entire extremity, or 3 to 4 mm per year on average. Once the decision for internal fixation of a fracture of the head or neck of the femur is made, stable fixation of the fracture is a higher priority than preservation of the physis. If stability is questionable, the internal fixation device should extend into the femoral head for rigid, stable fixation, regardless of the type of fracture or the age of the child.
  •  
    Anatomic reduction is imperative to decrease the incidence of nonunion and perhaps avascular necrosis.

Management of Expected Adverse Outcomes and Unexpected Complications Related to Hip Fractures (Table 26-6)

 
Table 26-6
Hip Fractures
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Table 26-6
Hip Fractures
Common Adverse Outcomes and Complications
  •  
    Avascular necrosis
  •  
    Malunion (coxa vara)
  •  
    Physeal arrest
  •  
    Nonunion
X
ON is the most serious and frequent complication of hip fractures in children and is the primary cause of poor results after fractures of the hip in children.72 Its overall prevalence is approximately 30%, based on the literature.22,58,84 The risk of ON is highest after displaced type IB, II, and III fractures (Fig. 26-11).15 In the meta-analysis by Moon and Mehlman,79 the incidence of ON in type I through type IV is 38%, 28%, 18%, and 5%, respectively. In addition to location of the fracture (via Delbet classification), ON is believed to be increased with increased fracture displacement and older age at the time of injury.70 Several studies report lower rates of ON in their series of patients treated within 24 hours of injury with prompt reduction and internal fixation.22,37,111 This approach to early reduction and stabilization may decrease ON by preventing further injury to the tenuous blood supply, and open reduction or capsulotomy may decrease intra-articular pressure caused by fracture hematoma.58,84,112 The later concept has equivocal support in the literature with some papers reporting that aspirating the hematoma may decrease the intracapsular pressure and increase blood flow to the femoral head22,84; others suggest that this may have little effect.58,74,90 A final important factor that may reduce ON is stability and quality of reduction: This is highlighted in a recent 30-year experience of hip fractures from Mayo Clinic.105 In this paper, ON was associated with inadequate reduction and use of older implant styles, yet timing and adding a capsulotomy was not a factor in ON. In our institution, we recognize that the die may already be cast at the time of injury, but we still advocate emergent anatomic reduction and stabilization of the fracture to reduce risk of ON. ON has been classified by Ratliff as follows: Type I, involvement of the whole head; type II, partial involvement of the head; and type III, an area of necrosis of the femoral neck from the fracture line to the physis (Fig. 26-12).98 Type I is the most severe and most common form and has the poorest prognosis. Type I probably results from damage to all of the retinacular epiphyseal vessels, type II from localized damage to one or more of the lateral epiphyseal vessels near their insertion into the anterolateral aspect of the femoral head, and type III from damage to the superior metaphyseal vessels. Type III is rare but has a good prognosis provided the fracture goes on to heal.98 Signs and symptoms of ON usually develop within the first year after injury, but many patients may not become symptomatic for up to 2 years.58,97 Some authors have utilized bone scanning for early detection of ON as further collapse may be prevented with use of bisphosphonate therapy. Ramachandran et al.89 treated 28 patients with early bone scan changes of ON from SCFE or femoral neck fracture. The group was treated with an intravenous bisphosphonate (pamidronate or zoledronate) for an average of 20 months, which greatly improved the outcome at 3-year follow-up.96 The long-term results of established ON are likely related to age of the patient and extent and location of the necrosis within the head; results are usually poor in over 60% of patients.19,29,38,87 There is no clearly effective treatment for established posttraumatic ON in children.58,97 Older children (more than 10 years) tend to have worse outcomes than younger children. Treatment of ON is controversial and inconclusive and is beyond the scope of this text. Ongoing research includes the role of redirectional osteotomy,71 distraction arthroplasty with external fixation, core decompression, vascularized fibular grafting (Fig. 26-13), and direct bone grafting. 
Figure 26-11
 
A: A 14-year-old girl with a type II fracture of the left femoral neck. B: After fixation with three cannulated screws. C: ON with collapse of the superolateral portion of the femoral head. D: After treatment with valgus osteotomy.
A: A 14-year-old girl with a type II fracture of the left femoral neck. B: After fixation with three cannulated screws. C: ON with collapse of the superolateral portion of the femoral head. D: After treatment with valgus osteotomy.
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Figure 26-11
A: A 14-year-old girl with a type II fracture of the left femoral neck. B: After fixation with three cannulated screws. C: ON with collapse of the superolateral portion of the femoral head. D: After treatment with valgus osteotomy.
A: A 14-year-old girl with a type II fracture of the left femoral neck. B: After fixation with three cannulated screws. C: ON with collapse of the superolateral portion of the femoral head. D: After treatment with valgus osteotomy.
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Figure 26-12
The three types of ON.
 
Type I, whole head; type II, partial head; and type III, femoral neck.
 
(Reprinted from Ratliff AH. Fractures of the neck of the femur in children. J Bone Joint Surg Br. 1962; 44:528–542, with permission.)
Type I, whole head; type II, partial head; and type III, femoral neck.
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Figure 26-12
The three types of ON.
Type I, whole head; type II, partial head; and type III, femoral neck.
(Reprinted from Ratliff AH. Fractures of the neck of the femur in children. J Bone Joint Surg Br. 1962; 44:528–542, with permission.)
Type I, whole head; type II, partial head; and type III, femoral neck.
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Figure 26-13
Vascularized fibular grafting for osteonecrosis of the femoral head.
 
(Redrawn after Aldrich JM III, Berend KR, Gunneson EE, et al. Free vascularized fibular grafting for the treatment of postcollapse osteonecrosis of the femoral head. J Bone Joint Surg Am. 2004; 86:87–101, with permission.)
(Redrawn after 


Aldrich JM III,

Berend KR,

Gunneson EE
, et al.
Free vascularized fibular grafting for the treatment of postcollapse osteonecrosis of the femoral head.
J Bone Joint Surg Am.
2004;
86:87–101, with permission.)
View Original | Slide (.ppt)
Figure 26-13
Vascularized fibular grafting for osteonecrosis of the femoral head.
(Redrawn after Aldrich JM III, Berend KR, Gunneson EE, et al. Free vascularized fibular grafting for the treatment of postcollapse osteonecrosis of the femoral head. J Bone Joint Surg Am. 2004; 86:87–101, with permission.)
(Redrawn after 


Aldrich JM III,

Berend KR,

Gunneson EE
, et al.
Free vascularized fibular grafting for the treatment of postcollapse osteonecrosis of the femoral head.
J Bone Joint Surg Am.
2004;
86:87–101, with permission.)
View Original | Slide (.ppt)
X

Coxa Vara in Hip Fractures

The prevalence of coxa vara has been reported to be approximately 20% to 30% in nine series58,63; although it is significantly lower in series in which internal fixation was used after reduction of displaced fractures.19 Coxa vara may be caused by malunion, ON of the femoral neck, premature physeal closure, or a combination of these problems (Fig. 26-14). Severe coxa vara raises the greater trochanter in relation to the femoral head, causing shortening of the extremity and leading to inefficiency of the abductors. Remodeling of an established malunion may occur if the child is less than 8 years, or with a neck–shaft angle greater than 110 degrees. Older patients with progressive deformity may not remodel and subtrochanteric valgus osteotomy may be considered to heal nonunion, and restore limb length and the abductor moment arm (Fig. 26-15).58,67 
Figure 26-14
 
A: A 12-year-old boy with a type III left hip fracture. Poor pin placement and varus malposition are evident. B: The fracture united in mild varus after hardware revision. C: Fourteen months after injury, collapse of the weight-bearing segment is evident. D: Six years after injury, coxa breva and trochanteric overgrowth are seen secondary to osteonecrosis, nonunion, and premature physeal closure.
A: A 12-year-old boy with a type III left hip fracture. Poor pin placement and varus malposition are evident. B: The fracture united in mild varus after hardware revision. C: Fourteen months after injury, collapse of the weight-bearing segment is evident. D: Six years after injury, coxa breva and trochanteric overgrowth are seen secondary to osteonecrosis, nonunion, and premature physeal closure.
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A: A 12-year-old boy with a type III left hip fracture. Poor pin placement and varus malposition are evident. B: The fracture united in mild varus after hardware revision. C: Fourteen months after injury, collapse of the weight-bearing segment is evident. D: Six years after injury, coxa breva and trochanteric overgrowth are seen secondary to osteonecrosis, nonunion, and premature physeal closure.
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Figure 26-14
A: A 12-year-old boy with a type III left hip fracture. Poor pin placement and varus malposition are evident. B: The fracture united in mild varus after hardware revision. C: Fourteen months after injury, collapse of the weight-bearing segment is evident. D: Six years after injury, coxa breva and trochanteric overgrowth are seen secondary to osteonecrosis, nonunion, and premature physeal closure.
A: A 12-year-old boy with a type III left hip fracture. Poor pin placement and varus malposition are evident. B: The fracture united in mild varus after hardware revision. C: Fourteen months after injury, collapse of the weight-bearing segment is evident. D: Six years after injury, coxa breva and trochanteric overgrowth are seen secondary to osteonecrosis, nonunion, and premature physeal closure.
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A: A 12-year-old boy with a type III left hip fracture. Poor pin placement and varus malposition are evident. B: The fracture united in mild varus after hardware revision. C: Fourteen months after injury, collapse of the weight-bearing segment is evident. D: Six years after injury, coxa breva and trochanteric overgrowth are seen secondary to osteonecrosis, nonunion, and premature physeal closure.
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Figure 26-15
 
A: A 10-year-old boy with a type III fracture treated without cast immobilization develops progressive varus deformity 4 months after surgery. Inset CT scan demonstrates delayed union. Valgus osteotomy is indicated for his progressive varus deformity and delayed healing. B: Three years after valgus osteotomy, the fracture is healed and the deformity corrected.
A: A 10-year-old boy with a type III fracture treated without cast immobilization develops progressive varus deformity 4 months after surgery. Inset CT scan demonstrates delayed union. Valgus osteotomy is indicated for his progressive varus deformity and delayed healing. B: Three years after valgus osteotomy, the fracture is healed and the deformity corrected.
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Figure 26-15
A: A 10-year-old boy with a type III fracture treated without cast immobilization develops progressive varus deformity 4 months after surgery. Inset CT scan demonstrates delayed union. Valgus osteotomy is indicated for his progressive varus deformity and delayed healing. B: Three years after valgus osteotomy, the fracture is healed and the deformity corrected.
A: A 10-year-old boy with a type III fracture treated without cast immobilization develops progressive varus deformity 4 months after surgery. Inset CT scan demonstrates delayed union. Valgus osteotomy is indicated for his progressive varus deformity and delayed healing. B: Three years after valgus osteotomy, the fracture is healed and the deformity corrected.
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Premature Physeal Closure in Hip Fractures

Premature physeal closure has occurred after approximately 28% of fractures.58 The risk of premature physeal closure increases with penetration by fixation devices or when ON is present. It is most common in patients who have type II or III ON (Fig. 26-14).97,98 
The capital femoral physis contributes only 13% of the growth of the entire extremity and normally closes earlier than most of the other physes in the lower extremity. As a result, shortening because of premature physeal closure is not significant except in very young children.15,60 Treatment for leg length discrepancy is indicated only for significant discrepancy (2.5 cm or more projected at maturity).58 If femoral growth arrest is expected because of the implant use or injury to the physis, the surgeon may consider concomitant greater trochanteric epiphysiodesis to maintain a more normal articular trochanteric relationship (Fig. 26-16). 
Figure 26-16
 
A: Greater trochanteric epiphysiodesis was performed at the time of open reduction and internal fixation of a pathologic femoral neck fracture (Fig. 26-1) in a 10-year-old boy. Because the implant crosses the physis, growth arrest is expected and trochanteric arrest may minimize trochanteric overgrowth. B: Seven-year follow-up shows that growth arrest occurred and some trochanteric mismatch is present despite prior epiphysiodesis.
A: Greater trochanteric epiphysiodesis was performed at the time of open reduction and internal fixation of a pathologic femoral neck fracture (Fig. 26-1) in a 10-year-old boy. Because the implant crosses the physis, growth arrest is expected and trochanteric arrest may minimize trochanteric overgrowth. B: Seven-year follow-up shows that growth arrest occurred and some trochanteric mismatch is present despite prior epiphysiodesis.
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Figure 26-16
A: Greater trochanteric epiphysiodesis was performed at the time of open reduction and internal fixation of a pathologic femoral neck fracture (Fig. 26-1) in a 10-year-old boy. Because the implant crosses the physis, growth arrest is expected and trochanteric arrest may minimize trochanteric overgrowth. B: Seven-year follow-up shows that growth arrest occurred and some trochanteric mismatch is present despite prior epiphysiodesis.
A: Greater trochanteric epiphysiodesis was performed at the time of open reduction and internal fixation of a pathologic femoral neck fracture (Fig. 26-1) in a 10-year-old boy. Because the implant crosses the physis, growth arrest is expected and trochanteric arrest may minimize trochanteric overgrowth. B: Seven-year follow-up shows that growth arrest occurred and some trochanteric mismatch is present despite prior epiphysiodesis.
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Nonunion in Hip Fractures

Nonunion occurs infrequently, with an overall incidence of 7% of hip fractures in children.58 Nonunion is a complication seen in types II and III fractures and is not generally seen after type I or type IV fractures. The primary cause of nonunion is failure to obtain or maintain an anatomic reduction.15,17 After femoral neck fracture in a child, pain should be gone and bridging new bone should be seen at the fracture site by 3 months after injury. A CT scan may be helpful to look for bridging bone. If no or minimal healing is seen by 3 to 6 months, the diagnosis of nonunion is established. Nonunion should be treated operatively as soon as possible. Either rigid internal fixation or subtrochanteric valgus osteotomy should be performed to allow compression across the fracture (Fig. 26-17).67,68 Because the approach necessary for bone grafting is extensive, it should be reserved for persistent nonunion. Internal fixation should extend across the site of the nonunion, and spica cast immobilization should be used in all but the most mature and cooperative adolescents. 
Figure 26-17
 
A: A 15-year-old girl with a markedly displaced type II femoral neck fracture. B: She underwent open reduction and internal fixation with two 7.3-mm cannulated screws and one 4.5-mm cannulated screw. Primary bone grafting of a large defect in the superior neck was also performed. C: Radiograph at 5 months showing a persistent fracture line. D: Six weeks after valgus intertrochanteric osteotomy. The fracture is healing.
A: A 15-year-old girl with a markedly displaced type II femoral neck fracture. B: She underwent open reduction and internal fixation with two 7.3-mm cannulated screws and one 4.5-mm cannulated screw. Primary bone grafting of a large defect in the superior neck was also performed. C: Radiograph at 5 months showing a persistent fracture line. D: Six weeks after valgus intertrochanteric osteotomy. The fracture is healing.
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Figure 26-17
A: A 15-year-old girl with a markedly displaced type II femoral neck fracture. B: She underwent open reduction and internal fixation with two 7.3-mm cannulated screws and one 4.5-mm cannulated screw. Primary bone grafting of a large defect in the superior neck was also performed. C: Radiograph at 5 months showing a persistent fracture line. D: Six weeks after valgus intertrochanteric osteotomy. The fracture is healing.
A: A 15-year-old girl with a markedly displaced type II femoral neck fracture. B: She underwent open reduction and internal fixation with two 7.3-mm cannulated screws and one 4.5-mm cannulated screw. Primary bone grafting of a large defect in the superior neck was also performed. C: Radiograph at 5 months showing a persistent fracture line. D: Six weeks after valgus intertrochanteric osteotomy. The fracture is healing.
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Other Complications in Hip Fractures

Infection is uncommon after hip fractures in children. The reported incidence of 1%1,8,10 is consistent with the expected infection rate in any closed fracture treated surgically with ORIF. Chondrolysis is exceedingly rare and has been reported only in two series.5,38 Care must be taken to avoid persistent penetration of hardware into the joint, which can cause chondrolysis in conditions such as SCFE. Finally, SCFE has been reported after fixation of an ipsilateral femoral neck fracture.59 

Summary, Controversies, and Future Directions Related to Hip Fractures

Pediatric femoral neck fractures have a relatively small incidence of recurrence compared to other lower extremity fractures but the potential for complications is much greater. Except for very young children the majority of these fractures should be treated with ORIF to assure an anatomic reduction. For CRIF to be successful the fracture must be reduced nearly anatomic. Fracture reduction should be done urgently (<24 hours). An anterior approach, anterior lateral approach or surgical dislocation is the chosen approach depending on the surgeon's experience and the type of fracture. Open surgical dislocation allows direct visualization of the fracture and the retinaculum, which may have some beneficial effect on the incidence of AVN but this is yet to be proven. There are a variety of fixation methods once the fracture is anatomically reduced. The goal is to avoid fixation across the physis but if the patient is older (>10 to 12 years) or fixation would otherwise be inadequate the rule is to cross the physis as fracture stability and union are more critical. In the future there may be better strategies to manage AVN should it occur. 

Stress Fractures of the Femoral Neck

Stress fractures of the femoral neck are extremely uncommon in children, and only a few cases have been published in the English-language literature. In one study of 40 stress fractures in children, there was only one femoral neck stress fracture.31 The rarity of such fractures underscores the need for a high index of suspicion when a child has unexplained hip pain. The differential can be long for hip pain in children, and early diagnosis and treatment are essential to avoid complete fracture with displacement. 

Mechanism

Stress fractures of the femoral neck in children usually result from repetitive cyclic loading of the hip, such as that produced by a new or increased activity. A recent increase in the repetitive activity is highly suggestive of the diagnosis. An increase in intensity of soccer,12 and an increase in distance running are examples of such activities. Younger children often present with a limp or knee pain and may not have a clear history of increased activity.70 Underlying metabolic disorders or immobilizations that weaken the bone may predispose to stress fracture. There is the increased awareness of vitamin D deficiency in children that may predispose to a femoral neck stress fracture.83 In adolescent female athletes, amenorrhea, anorexia nervosa, and osteoporosis have been implicated in the development of stress fractures of the femoral neck.49 
The usual presentation is that of progressive hip or groin pain with or without a limp. The pain may be perceived in the thigh or knee and may be mild enough so that it does not significantly limit activities. In the absence of displacement, examination typically reveals slight limitation of hip motion with increased pain, especially with internal rotation. Usually plain radiographs reveal the fracture, but in the first 4 to 6 weeks after presentation, plain films may be negative. If there are no changes or only linear sclerosis, a bone scan will help identify the fracture. MRI has been documented as a sensitive test for undisplaced fractures of the femoral neck. If a sclerotic lesion is seen on plain radiographs, the differential diagnosis should include osteoid osteoma, chronic sclerosing osteomyelitis, bone infarct, and osteosarcoma. Other causes of hip pain, include SCFE, Legg–Calvé–Perthes disease, infection, avulsion injuries of the pelvis, eosinophilic granuloma, and bony malignancies. Stress fractures unrelieved by rest or treatment may progress with activity to complete fracture with displacement.113 For this reason, prompt diagnosis and treatment are important. 

Classification

Femoral neck stress fractures have been classified into two types: Compression fractures and tension fractures.31 The compression type appears as reactive bone formation on the inferior cortex without cortical disruption. This type rarely becomes completely displaced but may collapse into a mild varus deformity,33 and compression types have been reported to progress to complete fracture without early treatment (Fig. 26-18).113 The tension type is a transverse fracture line appearing on the superior portion of the femoral neck. This type is inherently unstable because the fracture line is perpendicular to the lines of tension. Tension stress fractures have not been reported in children but may occur in skeletally mature teenagers.113 
Figure 26-18
 
A line drawing of stress fractures, comparing compression (A) and tension (B) types.
A line drawing of stress fractures, comparing compression (A) and tension (B) types.
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Figure 26-18
A line drawing of stress fractures, comparing compression (A) and tension (B) types.
A line drawing of stress fractures, comparing compression (A) and tension (B) types.
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Treatment

Compression-type fractures generally can be treated with a period of nonweight bearing on crutches. Partial weight bearing can be allowed at 6 weeks with progression to full weight bearing at 12 weeks provided that the pain is resolved and there is radiographic evidence of healing. Close follow-up and careful evaluation is mandatory to insure that the fracture heals without propagation. Underlying conditions should be evaluated and addressed. In small or uncooperative children, spica casting may be necessary. Displacement into varus, however minimal, mandates internal fixation. Tension fractures are at high risk for displacement and should be treated with in situ compression fixation using cannulated screws. 

Complications

Coxa vara is the most common complication of untreated compression-type fractures. Acute displacement of this type also has been described.95 Once displaced, the stress fracture is subject to all the complications of type II and type III displaced femoral neck fractures. 

Introduction to Hip Dislocations in Children

Traumatic hip dislocations are uncommon injuries in children, constituting less than 5% of pediatric dislocations.69 In one study, the author identified only 15 cases over a 20-year period at a large trauma center.4 The character of the injury tends to vary in those children under age 6 commonly suffer isolated hip dislocation from a low-energy injury, whereas older children require a high-energy mechanism to dislocate the hip, and these injuries are often associated with more severe trauma.4,8,41,48,88,103 Most hip dislocations in children can be reduced easily, and long-term outcome is generally good with prompt and complete reduction. Delay in reduction or neglected dislocations routinely do poorly, with a high incidence of AVN.7,10 Incomplete reductions can occur from interposed soft tissue or bony fragments, and postoperative imaging is mandatory to insure complete reduction.23,73 Difficult reductions or those that occur during the early teenage years (with a widened proximal femoral physis) should be performed with anesthesia, muscle relaxation, and the use of fluoroscopy to ensure that physeal separation does not occur.55,87 Open reduction may be needed if the hip cannot be reduced or if there is a femoral head fracture or an incarcerated fragment. Incomplete reductions may be treated open or arthroscopically.64 Complications, although uncommon, may occur, and these patients should be closely followed for recurrent subluxation, dislocation, and AVN.4,9,48,103 

Assessment of Hip Dislocation in Children

Mechanisms of Injury for Hip Dislocations in Children

The mechanism of injury in children with hip dislocation varies. Posterior hip dislocations are the most common8,103,107 and generally occur when a force is applied to the leg with the hip flexed and slightly adducted (Fig. 26-19). Anterior dislocations comprise fewer than 10% of hip dislocations (Fig. 26-20).4,103 Anterior dislocations can occur superiorly or inferiorly and result from forced abduction and external rotation. If the hip is extended while undergoing forced abduction and external rotation, it will dislocate anteriorly and superiorly; if the hip is flexed while abducted and externally rotated, the femoral head tends to dislocate anteriorly and inferiorly. In very rare cases, the femoral head may dislocate directly inferiorly, a condition known as luxatio erecta femoris or infracotyloid dislocation. Although this condition is extremely rare, it tends to occurs more commonly in children than adults.101 
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Figure 26-19
A typical posterior dislocation of the hip.
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Figure 26-20
An anterior (inferior) dislocation of the hip.
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In younger children, hip dislocations can occur with surprisingly little force, such as a fall while at play. The mechanism for hip dislocations in older children and adolescents is similar to that of adults in that significant trauma is needed. In a French study,4 the authors assessed children with hip dislocations and divided them into two groups by age: Those under 6 years (seven patients) and those aged 6 and older (seven patients). All the children under age 6 group had low-energy mechanisms and isolated hip dislocations without other injuries, but often had predisposing factors, such as hyperlaxity, coxa valga, or decreased acetabular coverage (Fig. 26-21). In the over 6-year-old group, all the dislocations were a result of higher-energy injuries and often had associated injuries.4 Football and motor vehicle accidents are the most common etiology, combining for over 50% of the dislocations in older children and adolescents.75,76 
Figure 26-21
 
A: A girl of age 4 years and 7 months presented with a posterior dislocation of the left hip. This is often the result of a low-energy injury, such as a fall from play. B: Frog-leg lateral radiograph at injury. C: Eight months after successful closed reduction, radiographic appearance is normal.
A: A girl of age 4 years and 7 months presented with a posterior dislocation of the left hip. This is often the result of a low-energy injury, such as a fall from play. B: Frog-leg lateral radiograph at injury. C: Eight months after successful closed reduction, radiographic appearance is normal.
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Figure 26-21
A: A girl of age 4 years and 7 months presented with a posterior dislocation of the left hip. This is often the result of a low-energy injury, such as a fall from play. B: Frog-leg lateral radiograph at injury. C: Eight months after successful closed reduction, radiographic appearance is normal.
A: A girl of age 4 years and 7 months presented with a posterior dislocation of the left hip. This is often the result of a low-energy injury, such as a fall from play. B: Frog-leg lateral radiograph at injury. C: Eight months after successful closed reduction, radiographic appearance is normal.
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Associated Injuries with Hip Dislocations in Children

Older children with dislocations due to a high-energy mechanism of injury often present with associated injuries. In one study of 42 patients, there were 17 fractures in nine patients and one closed head injury. Of the 17 fractures, 6 were posterior acetabular wall factures and 1 required ORIF.76 Careful evaluation of this injury in younger children with MRI is important because standard radiographic assessments and CT may underestimate the size of the fragment.100 Posterior dislocations of the femoral head can result in injury to the sciatic nerve in about 10% of adults and 5% of children. Partial recovery occurs in 60% to 70% of patients.27 The function of the sciatic nerve should be specifically tested at the time of the initial assessment and after reduction. 
Anterior dislocations can damage the femoral neurovascular bundle, and femoral nerve function and perfusion of the limb should be assessed. Tears of the capsule or acetabular labrum occur and prevent concentric reduction of the hip. Postreduction imaging must be carefully evaluated to ensure that there is no interposed soft tissue, such as the labrum or capsule, or osteochondral fragments. Rupture of the ligamentum teres is common in hip dislocations and can rarely be a cause of residual pain in some patients.17 
In addition, ipsilateral knee injuries commonly occur in high-energy injuries. One study evaluated the ipsilateral knees in 28 adults who had a traumatic hip dislocation and found that 75% had knee pain and 93% had MRI evidence of a knee injury; effusion, bone bruise, and meniscal tears were the most common findings.104 

Signs and Symptoms of Hip Dislocations in Children

The injured child has pain and inability to ambulate. Children sometimes feel the pain in the knee rather than in the hip. The hallmark of the clinical diagnosis of dislocation of the hip is abnormal positioning of the limb, which is not seen in fracture of the femur. Dislocations may spontaneously reduce, leaving the child with an incompletely reduced hip that is commonly misdiagnosed. Price et al.88 reported on three children who presented with a history of trauma and an incongruous hip. In all cases, the diagnosis was originally missed.94 

Imaging and Other Diagnostic Studies for Hip Dislocations in Children

Plain radiographs combined with the physical examination as described above usually confirm the diagnosis of a dislocated hip. Traumatic dislocations with spontaneous reductions may be more subtle and are often missed. Radiographs should be examined for fracture of the acetabular rim and proximal femur, which may be associated with dislocation. Any asymmetry of the joint space (Fig. 26-22), as compared to the contralateral hip, is a common finding with interposed tissue. MRI or CT scanning is useful for evaluating the acetabulum and may be useful in localizing intra-articular bony fragments or soft tissue interposition after reduction.54,73,76 The identification of nonbony fragments is difficult by CT without the use of concomitant arthrography.54 MRI is useful for evaluating soft tissues that may be interposed between the femoral head and acetabulum and has an advantage over plain radiographs and CT scan to detect cartilage fractures and defects prior to complete ossification of the acetabulum.53 MRI is especially helpful in nonconcentric reductions when the initial direction of dislocation is unknown, and in younger children with less bone ossification (Fig. 26-23).73,100 
Figure 26-22
Spontaneously reduced left hip but with persistent pain.
 
The joint space on the left is widened (A). The CT scan shows interposed soft tissue in the left hip (B).
The joint space on the left is widened (A). The CT scan shows interposed soft tissue in the left hip (B).
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Figure 26-22
Spontaneously reduced left hip but with persistent pain.
The joint space on the left is widened (A). The CT scan shows interposed soft tissue in the left hip (B).
The joint space on the left is widened (A). The CT scan shows interposed soft tissue in the left hip (B).
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Figure 26-23
Right hip pain after a fall.
 
The plain film shows no significant abnormality at time of injury (A). Persistent pain prompted an MRI 2 months after injury, which showed an interposed labrum in the joint (B, C).
The plain film shows no significant abnormality at time of injury (A). Persistent pain prompted an MRI 2 months after injury, which showed an interposed labrum in the joint (B, C).
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Figure 26-23
Right hip pain after a fall.
The plain film shows no significant abnormality at time of injury (A). Persistent pain prompted an MRI 2 months after injury, which showed an interposed labrum in the joint (B, C).
The plain film shows no significant abnormality at time of injury (A). Persistent pain prompted an MRI 2 months after injury, which showed an interposed labrum in the joint (B, C).
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Spontaneous reduction may occur after hip dislocation,81,91,94 and the diagnosis is commonly missed if it is not considered. The presence of air in the hip joint, which may be detectable on CT scan of the pelvis, is evidence that a hip dislocation has occurred.36 Dislocation and spontaneous reduction with interposed tissue can occur and lead to late arthropathy if untreated.91 Widening of the joint space on plain radiographs suggests the diagnosis. In patients with hip pain, a history of trauma, and widening of the joint space, consideration should be given to MRI to rule out dislocation with spontaneous relocation incarcerating soft tissue. If incarcerated soft tissues or osseous cartilage fragments are found, open or arthroscopic removal is required to obtain concentric reduction of the hip.64 

Classification of Hip Dislocations in Children

Hip dislocations in children are generally classified depending on where the femoral head lies in relation to the pelvis, namely posterior, anterior-superior, anterior-inferior, or infracotyloid.61 The dislocation is posterior more than 90% of the time. The Stewart–Milford classification is based on associated fractures. Grade I is defined as dislocation without an associated fracture or only a small bony avulsion of the acetabular rim, grade II is a posterior rim fracture with a stable hip after reduction, grade III is a posterior rim fracture with an unstable hip (Fig. 26-24), and grade IV is a dislocation that has an associated fracture of the femoral head or neck. 
Figure 26-24
 
A: A 12-year-old boy was tackled from behind in football. The right hip was dislocated. Reduction was easily achieved, but the hip was unstable posteriorly as a result of fracture of the posterior rim of the acetabulum. This is the most common fracture, occurring with hip dislocation. B: The fracture and capsule were fixed via a posterior approach. C: Oblique view shows reconstitution of the posterior rim.
A: A 12-year-old boy was tackled from behind in football. The right hip was dislocated. Reduction was easily achieved, but the hip was unstable posteriorly as a result of fracture of the posterior rim of the acetabulum. This is the most common fracture, occurring with hip dislocation. B: The fracture and capsule were fixed via a posterior approach. C: Oblique view shows reconstitution of the posterior rim.
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A: A 12-year-old boy was tackled from behind in football. The right hip was dislocated. Reduction was easily achieved, but the hip was unstable posteriorly as a result of fracture of the posterior rim of the acetabulum. This is the most common fracture, occurring with hip dislocation. B: The fracture and capsule were fixed via a posterior approach. C: Oblique view shows reconstitution of the posterior rim.
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Figure 26-24
A: A 12-year-old boy was tackled from behind in football. The right hip was dislocated. Reduction was easily achieved, but the hip was unstable posteriorly as a result of fracture of the posterior rim of the acetabulum. This is the most common fracture, occurring with hip dislocation. B: The fracture and capsule were fixed via a posterior approach. C: Oblique view shows reconstitution of the posterior rim.
A: A 12-year-old boy was tackled from behind in football. The right hip was dislocated. Reduction was easily achieved, but the hip was unstable posteriorly as a result of fracture of the posterior rim of the acetabulum. This is the most common fracture, occurring with hip dislocation. B: The fracture and capsule were fixed via a posterior approach. C: Oblique view shows reconstitution of the posterior rim.
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A: A 12-year-old boy was tackled from behind in football. The right hip was dislocated. Reduction was easily achieved, but the hip was unstable posteriorly as a result of fracture of the posterior rim of the acetabulum. This is the most common fracture, occurring with hip dislocation. B: The fracture and capsule were fixed via a posterior approach. C: Oblique view shows reconstitution of the posterior rim.
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Fracture-dislocation of the hip involving the femoral head or the acetabulum is much more unusual in children than in adults. Older adolescents may sustain adult-type fracture dislocations of the hip, and these are most commonly classified by the methods of Pipkin.92 He classified the head fractures as occurring either caudal to the fovea with a resultant small fragment (type 1) (see Fig. 21-24, Fig. 26-25), cranial to the fovea with a resultant large fragment (type 2), any combined femoral head and neck fracture (type 3), and any femoral neck fracture with an acetabular fracture (type 4). The youngest patient in his series from 1957 was 20, and most of these fractures were because of the relatively new phenomena of traffic accidents. 
Figure 26-25
 
A: A posterior dislocation associated after reduction with a femoral head fracture caudal to the ligamentum teres (Pipkin type 2). This is uncommon in children. This was treated with open reduction and internal fixation, with follow-up radiographs taken 1 year after the injury (B).
A: A posterior dislocation associated after reduction with a femoral head fracture caudal to the ligamentum teres (Pipkin type 2). This is uncommon in children. This was treated with open reduction and internal fixation, with follow-up radiographs taken 1 year after the injury (B).
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Figure 26-25
A: A posterior dislocation associated after reduction with a femoral head fracture caudal to the ligamentum teres (Pipkin type 2). This is uncommon in children. This was treated with open reduction and internal fixation, with follow-up radiographs taken 1 year after the injury (B).
A: A posterior dislocation associated after reduction with a femoral head fracture caudal to the ligamentum teres (Pipkin type 2). This is uncommon in children. This was treated with open reduction and internal fixation, with follow-up radiographs taken 1 year after the injury (B).
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Habitual dislocation of the hip has been described in children. In this condition, the child can actually voluntarily dislocate the hip. Many factors may contribute to this ability, including generalized ligamentous laxity or hyperlaxity disorders, excessive anteversion of the femur and acetabulum, and coxa valga.110 A commonly confused condition is snapping of the iliotibial band over the greater trochanter, and often the patient will describe this as “dislocating their hip.” Yet, the hip remains well seated both before and after the snap, which can be quite dramatic. The more common iliotibial band snapping can usually be differentiated from a true hip dislocation by examination, or if needed, radiographs with the hip “in” versus “out.” A snapping iliotibial band will demonstrate a well-seated hip on both radiographs. 

Pathoanatomy and Applied Anatomy Relating to Hip Dislocations in Children

The hip joint is a synovial ball and socket joint formed by the articulation of the rounded head of the femur and the cup-like acetabulum of the pelvis. If this is injured early in childhood, the growth of the acetabulum can be affected and result in acetabular dysplasia14,108 or impingement.42,47,86 

Treatment Options for Hip Dislocations in Children

The immediate goal in the treatment of a dislocated hip is to obtain concentric reduction as soon as possible. Reduction of a pediatric or adolescent hip dislocation should be considered an orthopedic emergency. Generally, closed reduction should be attempted initially. Successful closed reduction can be achieved with intravenous or intramuscular sedation in the emergency room in many patients.99 However, there is a risk of separating the femoral epiphysis from the femoral neck. Hence, complete muscle relaxation and the ability to urgently open the hip is often helpful, and this is best provided in the operating room with a general anesthetic. Open reduction is indicated if closed reduction is unsuccessful or incomplete. In children, especially in their early teenage years, cases of proximal physeal separation with attempted closed reduction have been reported, and therefore, the uses of fluoroscopy to assess the stability of the proximal femoral physis is highly recommended.55,87 
Several methods of closed reduction have been described for reduction of posterior dislocations. With any type of dislocation, traction along the axis of the thigh coupled with gentle manipulation of the hip often affects reduction after satisfactory relaxation of the surrounding muscles. 
Allis30 described a maneuver in which the patient is placed supine and the surgeon stands above the patient. For this reason, either the patient must be placed on the floor or the surgeon must climb onto the operating table. The knee is flexed to relax the hamstrings. While an assistant stabilizes the pelvis, the surgeon applies longitudinal traction along the axis of the femur and gently manipulates the femoral head over the rim of the acetabulum and back into the acetabulum. 
The gravity method of Stimson106 entails placing the patient prone with the lower limbs hanging over the edge of a table. An assistant stabilizes the patient while the surgeon applies gentle downward pressure with the knee and hip flexed 90 degrees, in an attempt to pull the femoral head anteriorly over the posterior rim of the acetabulum and back into the socket. Gentle internal and external rotations may assist in the reduction. 

Operative Treatment of Hip Dislocation in Children

If satisfactory closed reduction cannot be obtained using reasonable measures or the reduction is not concentric because of bone/soft tissue, it is appropriate to proceed with open reduction and inspection of the joint, to remove any obstructing soft tissues, and identify intra-articular osteochondral fragments. The approach for open reduction is the approaches discussed in the prior section (anterior, posterior, surgical dislocation) dependent on the direction of dislocation and surgeon experience. Surgeons with extensive hip arthroscopic experience can perform arthroscopic treatment of interposed soft tissue limiting a concentric reduction. In a nonreducible hip, imaging can be performed prior to reduction but it should not delay treatment. As mentioned previously, children in their early teenage years, cases of proximal physeal separation with attempted closed reduction have been reported, and therefore, the uses of fluoroscopy to assess the stability of the proximal femoral physis is highly recommended.55,87 

Author's Preferred Treatment for Hip Dislocations in Children

Urgent closed reduction by applying traction in line with the femur and gently manipulating the femoral head back into the acetabulum should be performed. A controlled reduction with sedation or general anesthesia and muscle relaxation in the operating room is preferable, and aggressive techniques should not be attempted without muscle relaxant. The use of fluoroscopy to monitor the reduction, especially in children over 12 with open physis, is important to insure that proximal femoral epiphysiolysis does not occur. Surgery is indicated for dislocations that are irreducible or for nonconcentric reductions. We recommend and MRI should be considered after reduction to assess for interposing fragments of bone, cartilage, or soft tissue. 

Surgical Procedures

Open reduction of a posterior dislocation should be performed through a posterolateral (Kocher–Langenbeck) approach or surgical dislocation approach. For the Kocher–Langenbeck approach the patient is positioned in the lateral decubitus position with the dislocated side facing up. The incision is centered on and just posterior to the greater trochanter and goes up into the buttock. Generally, a straight incision can be made with the hip flexed approximately 90 degrees. Once the fascia lata is incised, the femoral head can be palpated beneath or within the substance of the gluteus maximus muscle. The fibers of the gluteus maximus can then be divided by blunt dissection, exposing the dislocated femoral head. The path of dislocation is followed through the short external rotator muscles and capsule down to the acetabulum. The sciatic nerve lies on the short external rotators and should be identified and inspected. The piriformis may be draped across the acetabulum, obstructing the view of the reduction. It may be necessary to detach the short external rotators to see inside the joint. After the joint is inspected, repair of the fracture of the posterior acetabular rim can be performed in the standard fashion. 
Anterior dislocations should be approached through an anterior approach. This can be done through a bikini incision that uses the interval between the sartorius and the tensor fascia lata. The deep dissection follows the defect created by the femoral head down to the level of the acetabulum. 
A surgical dislocation approach would be particularly useful for hips that are reduced and are not concentric. The approach was described in detail with the last section. Patients are placed in the lateral decubitus position. The tensor fascia is opened distal to the trochanter and fascia proximal to the trochanter is incised on the anterior border of the gluteus maximus (Gibson modification). A trochanteric osteotomy is performed 10 to 15 mm in depth from anterior to the tip of the greater trochanter to the posterior portion of the vastus lateralis insertion. The capsule is exposed by elevation of the gluteus minimus along with the gluteus medius, vastus lateralis, vastus intermedius, and the mobilized trochanteric fragment. The dissection is performed anterior to the piriformis tendon and facilitated by flexion and external rotation of the hip. Once the capsule is exposed a capsulotomy is performed in a “z” fashion with the posterior border of the capsulotomy along the acetabular edge to protect the retinacular vessels. Placing the leg in a sterile anterior leg bag should easily dislocate the hip. The epiphysis should be provisionally pinned with a smooth K-wire if there is any concern of epiphysiolyis. 
The femoral head and acetabulum should be inspected for damage. Any small intra-articular fragments should be removed. The labrum and capsule should be inspected for repairable tears. Labral fragments that cannot be securely replaced should be excised, but repair should be attempted. Frequently, the labrum or hip capsule is entrapped in the joint. In the anterior approach the femoral head should be dislocated and any interposed soft tissue extracted. A Schanz screw or bone hook may be needed to displace the femur enough to see inside the joint in the anterior approach. Any bony fragments displaced from the femoral head of the acetabulum should have reduction and fixation if the size is significant. In younger hips the cartilaginous labral–chondral junction may be displaced from the bony rim. Suture anchor repair through the base of the labrum should be performed. 
The hip joint is then reduced under direct vision. The capsule should be repaired and in surgical dislocation the greater trochanter is reduced and secured with screws. Postreduction radiographs should be taken to confirm concentric reduction. If the joint appears slightly widened, repeat investigation is indicated to rule out interposed tissue. Slight widening may be because of fluid in the hip joint or decreased muscle tone, and this may improve over the next few days. 
Open injuries should be treated with immediate irrigation and debridement. The surgical incision should incorporate and enlarge the traumatic wound. Inspection should proceed as detailed above. Capsular repair should be attempted if the hip joint is not contaminated. The wound should be left open or should be well drained to prevent invasive infection. As in all open fractures, intravenous antibiotics should be administered and patients should be screened for tetanus. 
After reduction, a short period of immobilization should be instituted. In younger children, a spica cast can be used for 4 to 6 weeks; older cooperative children can be treated with hip abduction orthosis, total hip precautions and gradually return to ambulation with crutches.48,96,99 

Potential Pitfalls and Preventative Measures (Table 26-7)

 
Table 26-7
Hip Fractures
View Large
Table 26-7
Hip Fractures
Potential Pitfalls and Prevention
Pitfalls Preventions
Pitfall #1: Osteonecrosis Prevention 1a: Urgent reduction
Prevention 1b: Decompress the hip capsule by opening the hip capsule.
Pitfall #2: Nonconcentric reduction Prevention 2a: Postreduction imaging with a CT or an MRI. In younger children the impediments to a concentric reduction may be cartilaginous, therefore, an MRI would be preferred over a CT scan
Prevention 2b: Open hip reduction to remove or fix impediments to a concentric reduction.
Prevention 2c: Athroscopic fixation or removal of soft tissue impediments to a concentric reduction.
Pitfall #3: Epiphysiolyis Prevention 3a: In older children with an open physis it is critical to assure the physis is intact prior to reduction, and gentle reduction should be performed under general sedation and muscle relation with fluoroscopic evaluation to lessen the chance of the epiphysis separating from the metaphysis during the reduction.
Prevention 3b: None
X
  •  
    Reduce the hip urgently. The most devastating outcome is ON, and prolonged time to reduction (more than 6 hours) appears to be the greatest risk factor. In multitrauma patients, this concept needs to be expressed to the trauma team so that it can be prioritized properly.
  •  
    Look for associated fractures and other injuries. In older children, it is important to evaluate the posterior rim of the acetabulum after posterior dislocation to rule out fracture. Relying on plain radiographs and CT may underestimate the extent of damage to the posterior wall of the acetabulum in children because of the incomplete ossification of the pediatric bone. MRI may be required to adequately assess the posterior wall of the acetabulum in children.100
  •  
    Fractures at other sites in the femur must be considered. It is important to obtain radiographs that show the entire femur to rule out ipsilateral fracture. Careful evaluation of the entire patient is needed especially for high-energy injuries that result in a hip dislocation in older children and adults.
  •  
    Separation of the capital femoral epiphysis and femoral neck fracture has been reported in association with dislocation of the hip and the attempted reduction. Children in their early teenage years, aged 12 to 16, should have reduction performed with fluoroscopy under general anesthesia when possible. This strategy may avoid the possibility of displacing the proximal femoral epiphysis (with attendant increased ON risk) during attempted closed reduction (Fig. 26-26).
  •  
    Spontaneous relocation of a dislocation of the hip may occur with subsequent soft tissue or osteocartilaginous interposition. Failure to appreciate the presence of hip dislocation may lead to inadequate treatment. Traumatic hip subluxation may go undetected or may be treated as a sprain or strain if the diagnosis is not considered.81,94 After dislocation and spontaneous reduction, soft tissue may become interposed in the hip joint potentially resulting chronic arthropathy. In a child with posttraumatic hip pain without obvious deformity, the possibility of dislocation–relocation must be considered.
  •  
    Always image the hip for evaluation of interposed tissue after reduction. The incidence of widened joint space after hip reductions is as high as 26%.73 After reduction, hemarthrosis may initially cause the hip joint to appear slightly wider on the affected side, but this should decrease after a few days. If the hip fails to appear concentric, the possibility of interposed soft tissue must be considered and MRI or CT scan should be performed.44,51,91,99,109
  •  
    Long-term follow-up is important in children who undergo hip dislocation. Injury to the triradiate cartilage may cause acetabular dysplasia with growth.13 ON, although uncommon, may lead to early arthrosis, and this may not be identified radiographically for several years. If there has been a significant delay in time to reduction or the patient is otherwise at higher risk for ON, then consideration of a bone scan or MRI to evaluate for ON may be warranted, especially if early treatment with bisphosphonates is considered.
Figure 26-26
 
A: An 11-year-old boy dislocated his left hip while wrestling. B: The hip was easily reduced. C: After 5 months, hip pain led to an MRI, which shows ON of the capital femoral epiphysis. D: At 10 months after injury, there are typical changes of ON despite nonweight bearing.
A: An 11-year-old boy dislocated his left hip while wrestling. B: The hip was easily reduced. C: After 5 months, hip pain led to an MRI, which shows ON of the capital femoral epiphysis. D: At 10 months after injury, there are typical changes of ON despite nonweight bearing.
View Original | Slide (.ppt)
Figure 26-26
A: An 11-year-old boy dislocated his left hip while wrestling. B: The hip was easily reduced. C: After 5 months, hip pain led to an MRI, which shows ON of the capital femoral epiphysis. D: At 10 months after injury, there are typical changes of ON despite nonweight bearing.
A: An 11-year-old boy dislocated his left hip while wrestling. B: The hip was easily reduced. C: After 5 months, hip pain led to an MRI, which shows ON of the capital femoral epiphysis. D: At 10 months after injury, there are typical changes of ON despite nonweight bearing.
View Original | Slide (.ppt)
X

Management of Expected Adverse Outcomes and Unexpected Complications Related to Hip Dislocations in Children

ON occurs in about 10% of hip dislocations in children (Fig. 26-27).45,76,85,107 Urgent relocation may decrease the incidence of this complication.41,76,107 The risk of ON is probably also related to the severity of initial trauma.107 If the force of hip dislocation is so strong as to disrupt the obturator externus muscle, the posterior ascending vessels may be torn.85 In the rare case of dislocation with an intact capsule, increased intracapsular pressure as a result of hemarthrosis may have a role in developing ON.99 The type of postreduction care has not been shown to influence the rate of ON. 
Figure 26-27
 
Top: A: Anteroposterior radiograph of the pelvis, showing dislocation of the right hip. B: Anteroposterior radiograph of the right hip, showing the physeal separation after attempted closed reduction. Middle: Anteroposterior (A) and lateral (B) radiographs made after surgical dislocation, reduction, and fixation of the epiphysis through a trochanteric flip osteotomy. Bottom: Anteroposterior radiographs made during the 2-year period after surgical reconstruction.
 
(From Schoenecker JG, Kim Y, Ganz R. Treatment of traumatic separation of the proximal femoral epiphysis without development of osteonecrosis: A report of two cases. J Bone Joint Surg Am. 2010; 92:973–977, with permission.)
Top: A: Anteroposterior radiograph of the pelvis, showing dislocation of the right hip. B: Anteroposterior radiograph of the right hip, showing the physeal separation after attempted closed reduction. Middle: Anteroposterior (A) and lateral (B) radiographs made after surgical dislocation, reduction, and fixation of the epiphysis through a trochanteric flip osteotomy. Bottom: Anteroposterior radiographs made during the 2-year period after surgical reconstruction.
View Original | Slide (.ppt)
Figure 26-27
Top: A: Anteroposterior radiograph of the pelvis, showing dislocation of the right hip. B: Anteroposterior radiograph of the right hip, showing the physeal separation after attempted closed reduction. Middle: Anteroposterior (A) and lateral (B) radiographs made after surgical dislocation, reduction, and fixation of the epiphysis through a trochanteric flip osteotomy. Bottom: Anteroposterior radiographs made during the 2-year period after surgical reconstruction.
(From Schoenecker JG, Kim Y, Ganz R. Treatment of traumatic separation of the proximal femoral epiphysis without development of osteonecrosis: A report of two cases. J Bone Joint Surg Am. 2010; 92:973–977, with permission.)
Top: A: Anteroposterior radiograph of the pelvis, showing dislocation of the right hip. B: Anteroposterior radiograph of the right hip, showing the physeal separation after attempted closed reduction. Middle: Anteroposterior (A) and lateral (B) radiographs made after surgical dislocation, reduction, and fixation of the epiphysis through a trochanteric flip osteotomy. Bottom: Anteroposterior radiographs made during the 2-year period after surgical reconstruction.
View Original | Slide (.ppt)
X
Early technetium bone scanning with pinhole-collimated images detects ON as an area of decreased uptake. Findings on T2-weighted images are abnormal but of variable signal intensity. MRI may be falsely negative if performed within a few days of injury93; conversely, many perfusion defects seen on MRI spontaneously resolve after several months.46,93 As treatment for early ON develops this algorithm may change, and early assessment maybe considered for those at high risk of ON. If hips are followed by serial radiographs for ON, it is recommended that they be studied for at least 2 years after dislocation, because radiographic changes may appear late.8 
If ON develops, pain, loss of motion, and deformity of the femoral head are likely.10 ON in a young child resembles Perthes disease and may be treated like Perthes disease.10 Priorities are to maintain mobility and containment of the femoral head to maximize congruity after resolution. ON in older children should be treated as in adults and may require hip fusion, osteotomy, or reconstruction. If identified early, medical treatment with bisphosphonates or revascularization techniques, such as a vascularized fibular bone graft, can be considered.1,106 

Chondrolysis

Chondrolysis has been reported after hip dislocation in up to 6% of children45,51,56,88 and probably occurs as a result of articular damage at the time of dislocation. Chondrolysis cannot be reversed by medical means, and treatment should be symptomatic. Anti-inflammatory medicines and weight-relieving devices should be used as needed. Hip joint distraction with a hinged external fixator may improve range of motion and decrease pain.32 If the joint fails to reconstitute, fusion or reconstruction should be considered. 

Coxa Magna

Coxa magna occasionally occurs after hip dislocation. The reported incidence ranges from 0% to 47%.45,56,88 It is believed to occur as a result of posttraumatic hyperemia.88 In most children, this condition is asymptomatic and does not require any treatment.88 There is no intervention that will prevent coxa magna. 

Habitual Dislocation

Habitual or voluntary dislocation of the hip usually is unrelated to trauma. Many factors may contribute to this ability, including generalized ligamentous laxity, excessive anteversion of the femur and acetabulum, and coxa valga. Initial management should include counseling the child to cease the activity (with or without psychiatric counseling) and observation. If episodes of dislocation persist, permanent changes such as secondary capsular laxity or osteocartilaginous deformation of the hip may occur. These changes may lead to pain, residual subluxation, or degenerative joint disease. Conservative treatment should be initially attempted and may include simple observation with or without psychiatric counseling or immobilization with cast or brace. Hip stabilization by surgical means may be indicated for persistent painful episodes of hip despite conservative treatment.89,110 Knight et al. recently reported their 10-year follow-up of Down syndrome patients with habitual subluxation treated with a varus/derotation intertrochanteric osteotomy. They recommend surgery in these patients before age 7 and attempting to get the neck/shaft angle to 105 degrees to prevent later hip abnormality.65 Therefore, corrective surgery, if considered, should be performed only to correct specific anatomic abnormality and perhaps in patients with known ligamentous laxity. Surgery may include capsular plication, although bony correction with redirectional pelvic osteotomy, or osteotomy of the proximal femur would likely be more effective.110 

Heterotopic Ossification

Heterotopic ossification can result after closed reduction of hip dislocations in children. In one study, three children (all under 16 years of age) developed heterotopic ossification, one of which required surgical excision.76 

Interposed Soft Tissue

Interposed tissues may cause nonconcentric reduction or result in complete failure of closed reduction. Muscle, bone, articular cartilage, and labrum have been implicated.20,41,44,51,94,109 An MRI provides information on obstacles to complete reduction and the direction of the initial dislocation.44,109 Open reduction generally is necessary to clear impeding tissues from the joint.20,44,51,88,94,109 Untreated nonconcentric reduction may lead to permanent degenerative arthropathy. 

Late Presentation

Not all hip dislocations in children cause severe or incapacitating symptoms. Ambulation may even be possible. As a result, treatment may be delayed or the diagnosis missed until shortening of the limb and contracture are well established, making reduction difficult. Nearly all patients with a delayed treatment of traumatic hip dislocation develop ON.7,66 Prolonged heavy traction may be considered as method to effect reduction.48 If this fails, preoperative traction, extensive soft tissue release, or primary femoral shortening should be considered if open reduction is required. Open reduction will likely be difficult and will not always be successful. Even if the hip stays reduced, progressive arthropathy may lead to a stiff and painful hip. The likelihood of a good result decreases with the duration of dislocation. 

Nerve Injury

The sciatic nerve may be directly compressed by the femoral head after a posterior dislocation of the hip in 2% to 13% of patients.35,103,107 If the hip is expediently reduced, nerve function returns spontaneously in most patients.35,51 If the sciatic palsy is present prior to reduction, the nerve does not need to be explored unless open reduction is required for other reasons. If sciatic nerve function is shown to be intact and is lost during the reduction maneuver, the nerve should be explored to ensure that it has not displaced into the joint. Other nerves around the hip joint are rarely injured at dislocation. Treatment is generally expectant unless laceration or incarceration is suspected; if so, exploration is indicated. 

Recurrent Dislocation

Recurrence after traumatic hip dislocation is rare but occurs most frequently after posterior dislocation in children under 8 years of age7,43 or in children with known hyperlaxity (Down syndrome, Ehlers–Danlos disease). The incidence of recurrence is estimated to be less than 3%.88 Recurrence can be quite disabling, and in the long term may result in damage to the articular surfaces as a result of shear damage to the cartilaginous hip. Prolonged spica casting (at least 3 months) may be effective.77 Surgical exploration with capsulorrhaphy can be performed if conservative treatment fails.7,43,61 Prior to hip reconstruction, an MRI or arthrography is recommended to identify a capsular defect or redundancy.7 In older children, recurrent dislocation can occur as a result of a bony defect in the posterior rim of the acetabulum similar to that in adults and may require posterior acetabular reconstruction. 

Vascular Injury

Impingement on the femoral neurovascular bundle has been described after anterior hip dislocation in children, and this may occur in 25% of patients.107 The hip should be relocated as soon as possible to remove the offending pressure from the femoral vessels. If relocation of the hip fails to restore perfusion, immediate exploration of the femoral vessels is indicated. 

Summary, Controversies, and Future Directions Related to Hip Dislocations in Children

The treatment for hip disorders is evolving. We now have new surgical and medical treatment options for hip disorders such as surgical hip dislocation and hip arthroscopy. Although most do not directly apply to the urgent reduction of hip dislocations, they are applicable to the sequelae that occur. The use of bisphosphonates and other medications that inhibit bone resorption is an active area of research and may have direct effects on limiting collapse of the femoral head if ON occurs.1 This could soon change our paradigm for the evaluation of a hip after reduction of a dislocation, and early MRI or bone scans may be indicated. 
A host of surgical methods are available to manage deformity as a result of necrosis or hip instability. Techniques to increase vascularity, such as vascularized bone grafting, remain a controversial method to improve the natural history. Hinged distraction across the hip is now more commonly performed and much easier technically, given the newer generation of external fixation devices designed just for this purpose. Hinged distraction may play a role as a primary treatment (i.e., for chondrolysis) or as an adjunct to other techniques.32 Hip arthroscopy is much more commonly performed and allows for a much less invasive approach to removing loose bodies in the hip and assessing and treating soft tissue injuries.15,64 Together, these new techniques offer future opportunities to decrease the severity of known complications and potentially improve functional outcomes. Time and follow-up will be required to determine if these methods improve the natural history of these posttraumatic sequelae. 

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