Chapter 28: Principles of Malunions

Mark R. Brinker, Daniel P. O’Connor

Chapter Outline

Evaluation

Each malunited fracture presents a unique set of bony deformities that are described in terms of abnormalities of length, angulation, rotation, and translation. Also describing the location, magnitude, and direction of the deformity completes the characterization of the malunion. Proper evaluation allows the surgeon to determine an effective treatment plan for deformity correction. 

Clinical

Evaluation begins with a medical history and a review of all available medical records. The history should include the date and mechanism of injury of the initial fracture and all subsequent operative and nonoperative interventions. The history should also include descriptions of prior wound and bone infections, and prior culture reports should be obtained. All pre-injury medical problems, disabilities, or associated injuries should be noted. The patient’s current level of pain and functional limitations as well as medication use should be documented. 
Following the history, a physical examination is performed. The skin and soft tissues in the injury zone should be inspected. The presence of active drainage or sinus formation should be noted. 
The malunion site should be manually stressed to rule out motion and assess pain. In a solidly healed fracture with deformity, manual stressing of the malunion site should not elicit pain. If pain is elicited on manual stressing, the orthopedic surgeon should consider the possibility that the patient has an ununited fracture. 
A neurovascular examination of the limb and evaluation of active and passive motion of the joints proximal and distal to the malunion site should be performed. Reduced motion in a joint adjacent to a malunion site may alter both the treatment plan and the expectations for the ultimate functional outcome. Patients who have a periarticular malunion may also have a compensatory fixed deformity at an adjacent joint, which must be recognized to include its correction in the treatment plan. Correction of the malunion without addressing a compensatory joint deformity results in a straight bone with a maloriented joint, thus producing a disabled limb. The limb may appear aligned in these cases, but radiographic evaluation will reveal the joint deformity. If the patient cannot place the joint into the position that parallels the deformity at the malunion site (e.g., evert the subtalar joint into valgus in the presence of a tibial valgus malunion) the joint deformity is fixed and requires correction (Fig. 28-1). 
Figure 28-1
Angular deformity near a joint can result in a compensatory deformity through the joint.
 
For example, frontal plane deformities of the distal tibia can result in a compensatory frontal plane deformity of the subtalar joint. The deformity of the subtalar joint is fixed (A) if the patient’s foot cannot be positioned to parallel the deformity of the distal tibia or flexible (B) if the foot can be positioned parallel to the deformity of the distal tibia.
For example, frontal plane deformities of the distal tibia can result in a compensatory frontal plane deformity of the subtalar joint. The deformity of the subtalar joint is fixed (A) if the patient’s foot cannot be positioned to parallel the deformity of the distal tibia or flexible (B) if the foot can be positioned parallel to the deformity of the distal tibia.
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Figure 28-1
Angular deformity near a joint can result in a compensatory deformity through the joint.
For example, frontal plane deformities of the distal tibia can result in a compensatory frontal plane deformity of the subtalar joint. The deformity of the subtalar joint is fixed (A) if the patient’s foot cannot be positioned to parallel the deformity of the distal tibia or flexible (B) if the foot can be positioned parallel to the deformity of the distal tibia.
For example, frontal plane deformities of the distal tibia can result in a compensatory frontal plane deformity of the subtalar joint. The deformity of the subtalar joint is fixed (A) if the patient’s foot cannot be positioned to parallel the deformity of the distal tibia or flexible (B) if the foot can be positioned parallel to the deformity of the distal tibia.
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Radiographic

The plain radiographs from the original fracture show the type and severity of the initial bony injury. Subsequent plain radiographs show the status of orthopedic hardware (e.g., loose, broken, undersized) as well as document the timing of insertion or removal. The evolution of deformity—for example, gradual versus sudden—should be evaluated. 
The current radiographs are evaluated next. Anteroposterior (AP) and lateral radiographs of the involved bone, including the proximal and distal joints, are used to evaluate the axes of the involved bone. Manual measurement of standard radiographs or computer-assisted measurement of digital radiographs may be used with equivalent accuracy.88,92,99 Bilateral AP and lateral 51-inch radiographs are obtained for lower-extremity deformities to evaluate limb alignment (Fig. 28-2). Flexion/extension lateral radiographs may be useful to determine the arc of motion of the surrounding joints. 
Figure 28-2
 
(A) Bilateral weight-bearing 51-inch AP alignment radiograph and (B) a 51-inch lateral alignment radiograph, which are used to evaluate lower-extremity limb alignment.
(A) Bilateral weight-bearing 51-inch AP alignment radiograph and (B) a 51-inch lateral alignment radiograph, which are used to evaluate lower-extremity limb alignment.
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Figure 28-2
(A) Bilateral weight-bearing 51-inch AP alignment radiograph and (B) a 51-inch lateral alignment radiograph, which are used to evaluate lower-extremity limb alignment.
(A) Bilateral weight-bearing 51-inch AP alignment radiograph and (B) a 51-inch lateral alignment radiograph, which are used to evaluate lower-extremity limb alignment.
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The current radiographs are used to document the following characteristics: Limb alignment, joint orientation, anatomic axes, mechanical axes, and center of rotation of angulation (CORA). Normative values for the relations among these various parameters14,78 are used to assess deformities. 

Limb Alignment

Evaluation of limb alignment involves assessment of the frontal plane mechanical axis of the entire limb rather than single bones.35,45,47,76,77,91 In the lower extremity, the frontal plane mechanical axis of the entire limb is evaluated using the weight-bearing AP 51-inch alignment radiograph with the feet pointed forward (neutral rotation).41,49,82 
Mechanical axis deviation (MAD) is measured as the distance from the knee joint center to the line connecting the joint centers of the hip and ankle. The hip joint center is located at the center of the femoral head. The knee joint center is half the distance from the nadir between the tibial spines to the apex of the intercondylar notch on the femur. The ankle joint center is the center of the tibial plafond. 
Normally, the mechanical axis of the lower extremity lies 1 to 15 mm medial to the knee joint center (Fig. 28-3). If the lower-extremity mechanical axis is outside this range, the deformity is described as MAD (Fig. 28-3). MAD greater than 15 mm medial to the knee midpoint is varus malalignment; any MAD lateral to the knee midpoint is valgus malalignment. 
Figure 28-3
 
A: Mechanical axis of the lower extremity, which normally lies 1 to 15 mm medial to the knee joint center. B: Medial mechanical axis deviation, in which the mechanical axis of the lower extremity lies more than 15 mm medial to the knee joint center.
A: Mechanical axis of the lower extremity, which normally lies 1 to 15 mm medial to the knee joint center. B: Medial mechanical axis deviation, in which the mechanical axis of the lower extremity lies more than 15 mm medial to the knee joint center.
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Figure 28-3
A: Mechanical axis of the lower extremity, which normally lies 1 to 15 mm medial to the knee joint center. B: Medial mechanical axis deviation, in which the mechanical axis of the lower extremity lies more than 15 mm medial to the knee joint center.
A: Mechanical axis of the lower extremity, which normally lies 1 to 15 mm medial to the knee joint center. B: Medial mechanical axis deviation, in which the mechanical axis of the lower extremity lies more than 15 mm medial to the knee joint center.
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Long Bone Anatomic Axes

The anatomic and mechanical axes of the long bones are assessed in both the frontal plane (AP radiographs) and sagittal plane (lateral radiographs). The anatomic axes are defined by lines that pass through the center of the diaphysis along the length of the bone or bone segment. To identify the anatomic axis, the center of the transverse diameter of the diaphysis is identified at several points along the bone or bone segment. The line that passes through these points represents the anatomic axis (Fig. 28-4). 
Figure 28-4
 
A: Anatomic axis of the femur. B: Anatomic axis of the tibia.
A: Anatomic axis of the femur. B: Anatomic axis of the tibia.
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Figure 28-4
A: Anatomic axis of the femur. B: Anatomic axis of the tibia.
A: Anatomic axis of the femur. B: Anatomic axis of the tibia.
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In a normal bone, the anatomic axis is a single straight line. In a malunited bone with angulation, each bony segment can be defined by its own anatomic axis with a line through the center of the diameter of the diaphysis of each bone segment representing the respective anatomic axis for that segment (Fig. 28-5). In bones with multiapical or combined deformities, there may be multiple anatomic axes in the same plane (Fig. 28-5). 
Figure 28-5
 
A: A malunited tibia fracture with angulation showing the anatomic axis for each bony segment as a line through the center of the diameter of the respective diaphyseal segments. B: A malunited femur fracture with a multiapical deformity, showing multiple anatomical axes in the same plane.
A: A malunited tibia fracture with angulation showing the anatomic axis for each bony segment as a line through the center of the diameter of the respective diaphyseal segments. B: A malunited femur fracture with a multiapical deformity, showing multiple anatomical axes in the same plane.
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Figure 28-5
A: A malunited tibia fracture with angulation showing the anatomic axis for each bony segment as a line through the center of the diameter of the respective diaphyseal segments. B: A malunited femur fracture with a multiapical deformity, showing multiple anatomical axes in the same plane.
A: A malunited tibia fracture with angulation showing the anatomic axis for each bony segment as a line through the center of the diameter of the respective diaphyseal segments. B: A malunited femur fracture with a multiapical deformity, showing multiple anatomical axes in the same plane.
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Mechanical Axes

The mechanical axis of a long bone is defined as the line that passes through the joint centers of the proximal and distal joints. To identify the mechanical axis in a long bone, the joint centers are connected by a line (Fig. 28-6). The mechanical axis of the entire lower extremity was described above under limb alignment. 
A: The mechanical axis of the femur. B: The mechanical axis of the tibia.
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Figure 28-6
The mechanical axis of a long bone is defined as the line that passes through the joint centers of the proximal and distal joints.
A: The mechanical axis of the femur. B: The mechanical axis of the tibia.
A: The mechanical axis of the femur. B: The mechanical axis of the tibia.
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Joint Orientation Lines

Joint orientation describes the relation of a joint to the respective anatomic and mechanical axes of a long bone. Joint orientation lines are drawn on the AP and lateral radiographs in the frontal and sagittal planes, respectively. 
Hip orientation may be assessed in two ways in the frontal plane. The trochanter-head joint orientation line connects the tip of the greater trochanter with center of the hip joint (the center of the femoral head). The femoral neck joint orientation line connects the hip joint center with a series of points which bisect the diameter of the femoral neck. 
Knee orientation is represented in the frontal plane by joint orientation lines at the distal femur and the proximal tibia. The distal femur joint orientation line is drawn to connect the most distal points of the femoral condyles. The proximal tibial joint orientation line is drawn tangential to the subchondral lines of the medial and lateral tibial plateaus. The angle between the two knee joint orientation lines is called the joint line congruence angle (JLCA), which normally varies from 0 to 2 degrees medial JLCA (i.e., slight knee joint varus). A lateral JLCA of any degree represents valgus malorientation of the knee and a medial JLCA of 3 degrees or greater represents varus malorientation of the knee. 
Knee orientation is represented in the sagittal plane by joint orientation lines at the distal femur and the proximal tibia. The sagittal distal femur joint orientation line is drawn through the anterior and posterior junctions of the femoral condyles with the metaphysis. The sagittal proximal tibial joint orientation line is drawn tangential to the subchondral lines of the tibial plateau. 
Malorientation of the knee joint produces malalignment of the lower limb, but limb malalignment (MAD outside the normal range) is not necessarily due to knee joint malorientation. 
Ankle orientation is represented in the frontal plane by a line drawn through the subchondral line of the tibial plafond. Ankle orientation is represented in the sagittal plane by a line drawn through the most distal points of the anterior and posterior distal tibia. 

Joint Orientation Angles

The relation between the anatomic axes or the mechanical axes and the joint orientation lines can be referred to as joint orientation angles and are described using standard nomenclature (Table 28-1) (Fig. 28-7). 
Figure 28-7
Joint orientation angles.
 
A: Anatomic medial proximal femoral angle (aMPFA). B: Mechanical lateral proximal femoral angle (mLPFA). C: Neck shaft angle (NSA). D: Anatomic lateral distal femoral angle (aLDFA). E: Mechanical lateral distal femoral angle (mLDFA). F: Posterior distal femoral angle (PDFA). G: Medial proximal tibial angle (MPTA). H: Lateral distal tibial angle (LDTA). I: Posterior proximal tibial angle (PPTA). J: Anterior distal tibial angle (ADTA).
A: Anatomic medial proximal femoral angle (aMPFA). B: Mechanical lateral proximal femoral angle (mLPFA). C: Neck shaft angle (NSA). D: Anatomic lateral distal femoral angle (aLDFA). E: Mechanical lateral distal femoral angle (mLDFA). F: Posterior distal femoral angle (PDFA). G: Medial proximal tibial angle (MPTA). H: Lateral distal tibial angle (LDTA). I: Posterior proximal tibial angle (PPTA). J: Anterior distal tibial angle (ADTA).
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Figure 28-7
Joint orientation angles.
A: Anatomic medial proximal femoral angle (aMPFA). B: Mechanical lateral proximal femoral angle (mLPFA). C: Neck shaft angle (NSA). D: Anatomic lateral distal femoral angle (aLDFA). E: Mechanical lateral distal femoral angle (mLDFA). F: Posterior distal femoral angle (PDFA). G: Medial proximal tibial angle (MPTA). H: Lateral distal tibial angle (LDTA). I: Posterior proximal tibial angle (PPTA). J: Anterior distal tibial angle (ADTA).
A: Anatomic medial proximal femoral angle (aMPFA). B: Mechanical lateral proximal femoral angle (mLPFA). C: Neck shaft angle (NSA). D: Anatomic lateral distal femoral angle (aLDFA). E: Mechanical lateral distal femoral angle (mLDFA). F: Posterior distal femoral angle (PDFA). G: Medial proximal tibial angle (MPTA). H: Lateral distal tibial angle (LDTA). I: Posterior proximal tibial angle (PPTA). J: Anterior distal tibial angle (ADTA).
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Table 28-1
Normal Values for Joint Orientation Angles in the Lower Extremity
Bone–Plane Components Mean Value (degrees) Normal Range (degrees)
Femur–Frontal
Anatomic medial proximal femoral angle (aMPFA) Anatomic axis Trochanter-head line 84 80–89
Mechanical lateral proximal femoral angle (mLPFA) Mechanical axis Trochanter-head line 90 85–95
Neck shaft angle (NSA) Anatomic axis Femoral neck line 130 124–136
Anatomic lateral distal femoral angle (aLDFA) Anatomic axis Distal femoral joint orientation line 81 79–83
Mechanical lateral distal femoral angle (mLDFA) Mechanical axis Distal femoral joint orientation line 88 85–90
Femur–Sagittal
Posterior distal femoral angle (PDFA) Mid-diaphyseal line Sagittal distal femoral joint orientation line 83 79–87
Tibial–Frontal
Medial proximal tibial angle (MPTA) Mechanical axis Proximal tibial joint orientation line 87 85–90
Lateral distal tibial angle (LDTA) Mechanical axis Distal tibial joint orientation line 89 88–92
Tibial–Sagittal
Posterior proximal tibial angle (PPTA) Mid-diaphyseal line Sagittal proximal tibial joint orientation line 81 77–84
Anterior distal tibial angle (ADTA) Mid-diaphyseal line Sagittal distal tibial joint orientation line 80 78–82
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In order to draw a joint orientation angle in the lower extremity when a deformity is present, begin by drawing a joint orientation line. Next, identify the joint center, which will always lie on the joint orientation line and intersects the mechanical axis. The mechanical axis line of the bone segment immediately adjacent to the joint can then be drawn using one of the three methods: (1) using the population mean value for that particular joint orientation angle; (2) using the joint orientation angle of the contralateral extremity, assuming it is normal; or (3) by extending the mechanical axis of the neighboring bone. 
For example, in order to draw the mechanical lateral distal femoral angle (mLDFA) in a femur with a frontal plane deformity, the steps would be as follows. Step 1: Draw the distal femoral joint orientation line. Step 2: Start at the joint center and draw an 88-degree mLDFA (population normal mean value), which will define the mechanical axis of the distal femoral segment. Alternately, draw the mLDFA which mimics the contralateral distal femur (if normal), or extend the mechanical axis of the tibia proximally (if the tibia is normal) to define the distal femoral mechanical axis. 

Center of Rotation of Angulation

The intersection of the proximal axis and distal axis of a deformed bone is called the CORA (Fig. 28-8), which is the point about which a deformity may be rotated to achieve correction.22,30,34,46,72,7578,89 The angle formed by the two axes at the CORA is a measure of angular deformity in that plane. Either the anatomic or mechanical axes may be used to identify the CORA, but these axes cannot be mixed. For diaphyseal malunions, the anatomic axes are most convenient. For juxta-articular (metaphyseal, epiphyseal) deformities, the mechanical axis of the short segment is constructed using one of the three methods described above. 
Figure 28-8
 
A: Center of rotation of angulation (CORA) and bisector for a varus angulation deformity of the tibia. B: Multiapical tibial deformity showing that the apparent CORA joining the proximal and distal anatomic axes (solid lines) lies outside of the bone. A third anatomic axis for the middle segment (dashed line) shows two CORAs for this multiapical deformity that both lie within the bone.
A: Center of rotation of angulation (CORA) and bisector for a varus angulation deformity of the tibia. B: Multiapical tibial deformity showing that the apparent CORA joining the proximal and distal anatomic axes (solid lines) lies outside of the bone. A third anatomic axis for the middle segment (dashed line) shows two CORAs for this multiapical deformity that both lie within the bone.
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Figure 28-8
A: Center of rotation of angulation (CORA) and bisector for a varus angulation deformity of the tibia. B: Multiapical tibial deformity showing that the apparent CORA joining the proximal and distal anatomic axes (solid lines) lies outside of the bone. A third anatomic axis for the middle segment (dashed line) shows two CORAs for this multiapical deformity that both lie within the bone.
A: Center of rotation of angulation (CORA) and bisector for a varus angulation deformity of the tibia. B: Multiapical tibial deformity showing that the apparent CORA joining the proximal and distal anatomic axes (solid lines) lies outside of the bone. A third anatomic axis for the middle segment (dashed line) shows two CORAs for this multiapical deformity that both lie within the bone.
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To define the CORA, the proximal axis and distal axis of the bone are identified, and then the orientations of the proximal and distal joints are assessed. If the intersection of the proximal and distal axes lies at the point of obvious deformity in the bone and the joint orientations are normal, the intersection point is the CORA and the deformity is uniapical in the respective plane. If the intersection of the axes lies outside the point of obvious deformity or either joint orientation is abnormal, either a second CORA exists in that plane and the deformity is multiapical or a translational deformity exists in that plane, which is usually obvious on the radiograph. 
The CORA is used to plan the operative correction of angular deformities. Correction of angulation by rotating the bone around a point on the line that bisects the angle of the CORA (the “bisector”) ensures realignment of the anatomic and mechanical axes without introducing an iatrogenic translational deformity.34 The bisector is a line that passes through the CORA and bisects the angle formed by the proximal and distal axes (Fig. 28-8).78 Angular correction along the bisector results in complete deformity correction without the introduction of a translational deformity.14,72,74,76,77 All points which lie on the bisector can be considered to be CORAs because angulation about these points will result in realignment of the deformed bone (see Treatment—Osteotomies below). 
Note that the proximal half of the mechanical axis for the femur and a portion of the proximal humerus normally lie outside the bone, so the CORA that is identified using the mechanical axis of the femur may lie outside the bone as well although the deformity may be uniapical. By contrast, if the CORA identified using the anatomic axis of the femur or humerus, or either axis of the tibia, lies outside the bone, then a multiapical deformity exists (Fig. 28-8). 

Evaluation of the Various Deformity Types

Length

Deformities involving length include shortening and overdistraction and are characterized by their direction and magnitude. They are measured from joint center to joint center in centimeters on plain radiographs and compared to the contralateral normal extremity, using an x-ray marker to correct for magnification (Fig. 28-9).90 Shortening after an injury may result from bone loss (from the injury or debridement) or overriding of the healed fracture fragments. Overdistraction at the time of fracture fixation may result in a healed fracture with overlengthening of the bone. 
Figure 28-9
Bilateral standing 51-inch AP alignment radiograph reveals a 34-mm leg length inequality.
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Angulation

Deformities involving angulation are characterized by their magnitude and the direction of the apex of angulation. Angulation deformity of the diaphysis is often associated with limb malalignment (MAD), as described above. Angulation deformities of the metaphysis and epiphysis (juxta-articular deformities) can be difficult to characterize. The angle formed by the intersection of a joint orientation line and the anatomic or mechanical axis of the deformed bone should be measured. When the angle formed differs markedly from the contralateral normal limb (or normal values when the contralateral limb is abnormal), a juxta-articular deformity is present.14,74,77 The identification of the CORA is key in characterizing angular deformities and planning their correction. 
Pure frontal or sagittal plane angular deformities are simple to characterize. Since the deformity appears only on the AP or lateral radiograph, respectively. If, however, the AP and lateral radiographs both appear to have angulation with CORAs at the same level on both views, the orientation of the angulation deformity is in an oblique plane (Fig. 28-10). Characterization of the magnitude and direction of oblique plane deformities can be computed from the AP and lateral radiographic measures using either the trigonometric or graphic method.18,36,78 Using the trigonometric method, the magnitude of an oblique plane angular deformity is 
and the orientation (relative to the frontal plane) of an oblique plane deformity is 
Figure 28-10
A 28-year-old woman presented with complaints of her leg “going out” and her knee hyperextending.
 
A: 51-inch AP alignment radiograph reveals a 6-degree apex medial deformity with the CORA 6.5 cm distal to the proximal tibial joint orientation line, and (B) the lateral alignment radiograph shows a 17-degree apex posterior angulation with a CORA 6.5 cm distal to the proximal tibial joint orientation line. This patient has an oblique plane angular deformity without translation.
A: 51-inch AP alignment radiograph reveals a 6-degree apex medial deformity with the CORA 6.5 cm distal to the proximal tibial joint orientation line, and (B) the lateral alignment radiograph shows a 17-degree apex posterior angulation with a CORA 6.5 cm distal to the proximal tibial joint orientation line. This patient has an oblique plane angular deformity without translation.
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Figure 28-10
A 28-year-old woman presented with complaints of her leg “going out” and her knee hyperextending.
A: 51-inch AP alignment radiograph reveals a 6-degree apex medial deformity with the CORA 6.5 cm distal to the proximal tibial joint orientation line, and (B) the lateral alignment radiograph shows a 17-degree apex posterior angulation with a CORA 6.5 cm distal to the proximal tibial joint orientation line. This patient has an oblique plane angular deformity without translation.
A: 51-inch AP alignment radiograph reveals a 6-degree apex medial deformity with the CORA 6.5 cm distal to the proximal tibial joint orientation line, and (B) the lateral alignment radiograph shows a 17-degree apex posterior angulation with a CORA 6.5 cm distal to the proximal tibial joint orientation line. This patient has an oblique plane angular deformity without translation.
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Using the graphic method, the magnitude of an oblique plane angular deformity is 
and the orientation (relative to the frontal plane) of an oblique plane deformity is 
The graphic method, based on the pythagorean theorem, approximates the exact trigonometric method. The error of approximation for angular deformities using the graphic method is less than 4 degrees unless the frontal and sagittal plane magnitudes are both greater than 45 degrees.14,46,72,74,76,77 
When the CORA is at a different level on the AP and lateral radiographs, a translational deformity is present in addition to an angulation deformity (Fig. 28-11). 
Figure 28-11
 
A: Frontal and (B) sagittal views of a tibia with an angulation–translational deformity. Note that the angulation deformity is evident only on the frontal view and the translational deformity is evident only on the sagittal view. C: The oblique view showing both deformities.
A: Frontal and (B) sagittal views of a tibia with an angulation–translational deformity. Note that the angulation deformity is evident only on the frontal view and the translational deformity is evident only on the sagittal view. C: The oblique view showing both deformities.
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Figure 28-11
A: Frontal and (B) sagittal views of a tibia with an angulation–translational deformity. Note that the angulation deformity is evident only on the frontal view and the translational deformity is evident only on the sagittal view. C: The oblique view showing both deformities.
A: Frontal and (B) sagittal views of a tibia with an angulation–translational deformity. Note that the angulation deformity is evident only on the frontal view and the translational deformity is evident only on the sagittal view. C: The oblique view showing both deformities.
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A multiapical deformity is defined by the presence of more than one CORA on either the AP or lateral radiograph (or both). In a multiapical deformity without translation, one of the joints will appear maloriented relative to the anatomic axis of the respective segment. For multiapical deformity, the anatomic axis of the segment nearest the joint with malorientation provides a third line that intersects both of the existing lines within the bone. These intersections are the sites of the multiple CORAs (Fig. 28-12). 
Figure 28-12
 
(A) AP and (B) lateral long-leg radiographs of a 27-year-old woman with a multiapical deformity of the femur, a large lateral mechanical axis deviation, a 13-cm leg length discrepancy, superior subluxation of the hip joint, degenerative hip joint disease, and a history of developmental dysplasia of the hip, proximal femoral focal deficiency, and Wagner osteotomy in childhood. The staged treatment plan included deformity correction, followed by femoral lengthening, and finally hip arthroplasty. C: Use of tracing paper and (D) three-dimensional CT reconstruction of the femur to facilitate treatment planning. The multiapical deformity and its three CORAs can be seen on these images. E: AP radiograph 1 month following multiapical deformity correction and intramedullary nailing showing the location and orientation of the three osteotomy sites. F: AP radiograph 7 months following deformity correction shows solid bony union at all three corticotomy sites.
(A) AP and (B) lateral long-leg radiographs of a 27-year-old woman with a multiapical deformity of the femur, a large lateral mechanical axis deviation, a 13-cm leg length discrepancy, superior subluxation of the hip joint, degenerative hip joint disease, and a history of developmental dysplasia of the hip, proximal femoral focal deficiency, and Wagner osteotomy in childhood. The staged treatment plan included deformity correction, followed by femoral lengthening, and finally hip arthroplasty. C: Use of tracing paper and (D) three-dimensional CT reconstruction of the femur to facilitate treatment planning. The multiapical deformity and its three CORAs can be seen on these images. E: AP radiograph 1 month following multiapical deformity correction and intramedullary nailing showing the location and orientation of the three osteotomy sites. F: AP radiograph 7 months following deformity correction shows solid bony union at all three corticotomy sites.
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(A) AP and (B) lateral long-leg radiographs of a 27-year-old woman with a multiapical deformity of the femur, a large lateral mechanical axis deviation, a 13-cm leg length discrepancy, superior subluxation of the hip joint, degenerative hip joint disease, and a history of developmental dysplasia of the hip, proximal femoral focal deficiency, and Wagner osteotomy in childhood. The staged treatment plan included deformity correction, followed by femoral lengthening, and finally hip arthroplasty. C: Use of tracing paper and (D) three-dimensional CT reconstruction of the femur to facilitate treatment planning. The multiapical deformity and its three CORAs can be seen on these images. E: AP radiograph 1 month following multiapical deformity correction and intramedullary nailing showing the location and orientation of the three osteotomy sites. F: AP radiograph 7 months following deformity correction shows solid bony union at all three corticotomy sites.
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Figure 28-12
(A) AP and (B) lateral long-leg radiographs of a 27-year-old woman with a multiapical deformity of the femur, a large lateral mechanical axis deviation, a 13-cm leg length discrepancy, superior subluxation of the hip joint, degenerative hip joint disease, and a history of developmental dysplasia of the hip, proximal femoral focal deficiency, and Wagner osteotomy in childhood. The staged treatment plan included deformity correction, followed by femoral lengthening, and finally hip arthroplasty. C: Use of tracing paper and (D) three-dimensional CT reconstruction of the femur to facilitate treatment planning. The multiapical deformity and its three CORAs can be seen on these images. E: AP radiograph 1 month following multiapical deformity correction and intramedullary nailing showing the location and orientation of the three osteotomy sites. F: AP radiograph 7 months following deformity correction shows solid bony union at all three corticotomy sites.
(A) AP and (B) lateral long-leg radiographs of a 27-year-old woman with a multiapical deformity of the femur, a large lateral mechanical axis deviation, a 13-cm leg length discrepancy, superior subluxation of the hip joint, degenerative hip joint disease, and a history of developmental dysplasia of the hip, proximal femoral focal deficiency, and Wagner osteotomy in childhood. The staged treatment plan included deformity correction, followed by femoral lengthening, and finally hip arthroplasty. C: Use of tracing paper and (D) three-dimensional CT reconstruction of the femur to facilitate treatment planning. The multiapical deformity and its three CORAs can be seen on these images. E: AP radiograph 1 month following multiapical deformity correction and intramedullary nailing showing the location and orientation of the three osteotomy sites. F: AP radiograph 7 months following deformity correction shows solid bony union at all three corticotomy sites.
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(A) AP and (B) lateral long-leg radiographs of a 27-year-old woman with a multiapical deformity of the femur, a large lateral mechanical axis deviation, a 13-cm leg length discrepancy, superior subluxation of the hip joint, degenerative hip joint disease, and a history of developmental dysplasia of the hip, proximal femoral focal deficiency, and Wagner osteotomy in childhood. The staged treatment plan included deformity correction, followed by femoral lengthening, and finally hip arthroplasty. C: Use of tracing paper and (D) three-dimensional CT reconstruction of the femur to facilitate treatment planning. The multiapical deformity and its three CORAs can be seen on these images. E: AP radiograph 1 month following multiapical deformity correction and intramedullary nailing showing the location and orientation of the three osteotomy sites. F: AP radiograph 7 months following deformity correction shows solid bony union at all three corticotomy sites.
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Rotation

A rotational deformity occurs about the longitudinal axis of the bone. Rotational deformities are described in terms of their magnitude and the position (internal or external rotation) of the distal segment relative to the proximal segment. Identification of a rotational deformity and quantification of the magnitude can be done using clinical measurements,100 axial computed tomography (CT) (Fig. 28-13),9 or AP and lateral radiographs with either trigonometric calculation or graphical approximation.78 While axial CT and the radiographic methods allow for more precise measurement of rotational deformities, the more convenient clinical measurement method often results in measures of sufficient accuracy to allow for adequate correction.100 
Figure 28-13
 
A: Clinical photograph of a 38-year-old woman who presented 9 months after nail fixation of a tibial fracture. She complained of her right foot “pointing outward.” B: Plain radiographs show what appears to be a healed fracture following tibial nailing. Comparison of the proximal and distal tibias bilaterally was consistent with malrotation of the right distal tibia. C: CT scans of both proximal and distal tibias show asymmetric external rotation of the right distal tibia which measures 42 degrees. The CT scan also confirmed solid bony union at the fracture site.
A: Clinical photograph of a 38-year-old woman who presented 9 months after nail fixation of a tibial fracture. She complained of her right foot “pointing outward.” B: Plain radiographs show what appears to be a healed fracture following tibial nailing. Comparison of the proximal and distal tibias bilaterally was consistent with malrotation of the right distal tibia. C: CT scans of both proximal and distal tibias show asymmetric external rotation of the right distal tibia which measures 42 degrees. The CT scan also confirmed solid bony union at the fracture site.
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A: Clinical photograph of a 38-year-old woman who presented 9 months after nail fixation of a tibial fracture. She complained of her right foot “pointing outward.” B: Plain radiographs show what appears to be a healed fracture following tibial nailing. Comparison of the proximal and distal tibias bilaterally was consistent with malrotation of the right distal tibia. C: CT scans of both proximal and distal tibias show asymmetric external rotation of the right distal tibia which measures 42 degrees. The CT scan also confirmed solid bony union at the fracture site.
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Figure 28-13
A: Clinical photograph of a 38-year-old woman who presented 9 months after nail fixation of a tibial fracture. She complained of her right foot “pointing outward.” B: Plain radiographs show what appears to be a healed fracture following tibial nailing. Comparison of the proximal and distal tibias bilaterally was consistent with malrotation of the right distal tibia. C: CT scans of both proximal and distal tibias show asymmetric external rotation of the right distal tibia which measures 42 degrees. The CT scan also confirmed solid bony union at the fracture site.
A: Clinical photograph of a 38-year-old woman who presented 9 months after nail fixation of a tibial fracture. She complained of her right foot “pointing outward.” B: Plain radiographs show what appears to be a healed fracture following tibial nailing. Comparison of the proximal and distal tibias bilaterally was consistent with malrotation of the right distal tibia. C: CT scans of both proximal and distal tibias show asymmetric external rotation of the right distal tibia which measures 42 degrees. The CT scan also confirmed solid bony union at the fracture site.
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A: Clinical photograph of a 38-year-old woman who presented 9 months after nail fixation of a tibial fracture. She complained of her right foot “pointing outward.” B: Plain radiographs show what appears to be a healed fracture following tibial nailing. Comparison of the proximal and distal tibias bilaterally was consistent with malrotation of the right distal tibia. C: CT scans of both proximal and distal tibias show asymmetric external rotation of the right distal tibia which measures 42 degrees. The CT scan also confirmed solid bony union at the fracture site.
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To measure tibial malrotation using clinical examination, the position of the foot axis, as indicated by a line running from the second toe through the center of the calcaneus, is compared to the projection of either the femoral or the tibial anatomic axis. To use the femoral axis, the patient is positioned prone or sits with the knee flexed to 90 degrees. The examiner measures the deviation of the foot axis from the line of the femoral axis; any deviation is considered to represent tibial malrotation. To use the tibial axis, the patient stands with the patella facing anteriorly (i.e., aligned in the frontal plane). To measure tibial malrotation, the examiner measures the deviation of the foot axis from the anterior projection of the tibial anatomic axis in the sagittal plane; any deviation of the foot axis from the tibial anatomic axis is considered to represent tibial malrotation. 
To measure a femoral rotational deformity using clinical examination, the patient is positioned prone with the knee flexed to 90 degrees and the femoral condyles parallel to the examination table. The femur is passively rotated internally and externally by the examiner, and the respective angular excursions of the tibia are measured. Asymmetry of rotation in comparison to the opposite side indicates a femoral rotational deformity. If the patient also has a tibial angulation deformity, the tibia will not be perpendicular to the examination table when the femoral condyles are so positioned; tibial angulation deformity will cause an apparent asymmetry in femoral rotation. In this case, the rotational excursions of the tibia must be adjusted for the magnitude of the tibial angular deformity to avoid an incorrect assessment of femoral rotation. 

Translation

Translational deformities may result from malunion following either a fracture or an osteotomy. Translational deformities are characterized by their plane, direction, magnitude, and level. The direction of a translational deformity is described in terms of the position of the distal segment relative to the proximal segment (medial, lateral, anterior, posterior), except for the femoral and humeral heads in which case the description is the position of the head relative to the shaft. Translational deformities may occur in an oblique plane, and trigonometric or graphical methods similar to those described for characterizing angulation deformities may be used to identify the plane and direction of the deformity.18,36,78 Magnitude of translation is measured as the horizontal distance from the proximal segment’s anatomic axis to the distal segment’s anatomic axis at the level of the proximal end of the distal segment (Fig. 28-14). 
Figure 28-14
Method for measuring the magnitude of translational deformities.
 
In this example, with both angulation and translation, the magnitude of the translational deformity is the horizontal distance from the proximal segment’s anatomical axis to the distal segment’s anatomical axis at the level of the proximal end of the distal segment.
In this example, with both angulation and translation, the magnitude of the translational deformity is the horizontal distance from the proximal segment’s anatomical axis to the distal segment’s anatomical axis at the level of the proximal end of the distal segment.
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Figure 28-14
Method for measuring the magnitude of translational deformities.
In this example, with both angulation and translation, the magnitude of the translational deformity is the horizontal distance from the proximal segment’s anatomical axis to the distal segment’s anatomical axis at the level of the proximal end of the distal segment.
In this example, with both angulation and translation, the magnitude of the translational deformity is the horizontal distance from the proximal segment’s anatomical axis to the distal segment’s anatomical axis at the level of the proximal end of the distal segment.
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Treatment

The clinical and radiographic evaluation of the deformity provides the information needed to develop a treatment plan. Following evaluation, the deformity is characterized by its type (length, angulation, rotational, translational, or combined), the direction of the apex (anterior, lateral, posterolateral, etc.), its orientation plane, its magnitude, and the level of the CORA. 
The status of the soft tissues may impact the surgical treatment of a bony deformity. Preoperative planning should include an evaluation of overlying soft tissue free flaps and skin grafts. In addition, scarring, tethering of neurovascular bundles, and infection may require modifications to the treatment plan in order to address these concomitant conditions in addition to correcting the malunion. Furthermore, if neurovascular structures lie on the concave side of an angular deformity, acute correction may lead to a traction injury and temporary or permanent complications. In such cases, gradual deformity correction may be preferable to allow for gradual accommodation of the nerves or vasculature to mitigate complications. 

Osteotomies

An osteotomy is used to separate the deformed bone segments to allow realignment of the anatomic and mechanical axes. The ability of an osteotomy to restore alignment depends on the location of the CORA, the axis about which correction is performed (the correction axis), and the location of the osteotomy. While the CORA is defined by the type, direction, and magnitude of the deformity, the correction axis depends on the location and type of the osteotomy, the soft tissues, and the choice of fixation technique. The relation of these three factors to one another determines the final position of the bone segments. Reduction following osteotomy produces one of the three possible results: (1) realignment through angulation alone; (2) realignment through angulation and translation; and (3) realignment through angulation and translation with an iatrogenic residual translational abnormality. 
When the CORA, correction axis, and osteotomy lie at the same location, the bone will realign through angulation alone, without translation (Fig. 28-15A). When the CORA and correction axis are at the same location but the osteotomy is made proximal or distal to that location, the bone will realign through both angulation and translation (Fig. 28-15B). When the CORA is at a location different than the correction axis as well as different from the osteotomy, correction of angulation aligns the proximal and distal axes in parallel but excess translation occurs and results in an iatrogenic translational deformity (Fig. 28-15C). 
Figure 28-15
Possible results when using osteotomy for correction of deformity.
 
A: The CORA, the correction axis, and the osteotomy all lie at the same location; the bone realigns through angulation alone, without translation. B: The CORA and the correction axis lie in the same location but the osteotomy is proximal or distal to that location; the bone realigns through both angulation and translation. C: The CORA lies at one location and the correction axis and the osteotomy lie in a different location; correction of angulation results in an iatrogenic translational deformity.
A: The CORA, the correction axis, and the osteotomy all lie at the same location; the bone realigns through angulation alone, without translation. B: The CORA and the correction axis lie in the same location but the osteotomy is proximal or distal to that location; the bone realigns through both angulation and translation. C: The CORA lies at one location and the correction axis and the osteotomy lie in a different location; correction of angulation results in an iatrogenic translational deformity.
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Figure 28-15
Possible results when using osteotomy for correction of deformity.
A: The CORA, the correction axis, and the osteotomy all lie at the same location; the bone realigns through angulation alone, without translation. B: The CORA and the correction axis lie in the same location but the osteotomy is proximal or distal to that location; the bone realigns through both angulation and translation. C: The CORA lies at one location and the correction axis and the osteotomy lie in a different location; correction of angulation results in an iatrogenic translational deformity.
A: The CORA, the correction axis, and the osteotomy all lie at the same location; the bone realigns through angulation alone, without translation. B: The CORA and the correction axis lie in the same location but the osteotomy is proximal or distal to that location; the bone realigns through both angulation and translation. C: The CORA lies at one location and the correction axis and the osteotomy lie in a different location; correction of angulation results in an iatrogenic translational deformity.
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Osteotomies can be classified by cut (straight or dome [actually not truly shaped like a dome, but cylindrical]) and type (opening, closing, neutral). A straight cut, such as a transverse or wedge osteotomy, is made such that the opposing bone ends have flat surfaces. A dome osteotomy is made such that the opposing bone ends have congruent convex and concave cylindrical surfaces. The type describes the rotation of the bone segments relative to one another at the osteotomy site. 
Selection of the osteotomy type depends on the type, magnitude, and direction of deformity, the proximity of the deformity to a joint, the location and its effect on the soft tissues, and the type of fixation selected. In certain cases, a small iatrogenic deformity may be acceptable if it is expected to have no effect on the patient’s final functional outcome. This situation may be preferable to an osteotomy type that requires an unfamiliar fixation method or a fixation technique that the patient may tolerate poorly. 

Wedge Osteotomy

The type of wedge osteotomy is determined by the location of the osteotomy relative to the locations of the CORA and the correction axis. When the CORA and correction axis are in the same location (to avoid translational deformity), they may lie on the cortex on the convex side of the deformity, on the cortex on the concave side of the deformity, or in the middle of the bone (Fig. 28-16). 
Figure 28-16
Wedge osteotomies; the osteotomy is made at the level of the CORA and the correction axis in all of these examples.
 
A: Opening wedge osteotomy. The CORA and correction axis lie on the cortex on the convex side of the deformity. The cortex on the concave side of the deformity is distracted to restore alignment, opening an empty wedge that traverses the diameter of the bone. Opening wedge osteotomy increases final bone length. B: Neutral wedge osteotomy. The CORA and correction axis lie in the middle of the bone. The concave side cortex is distracted and the convex side cortex is compressed. A bone wedge is removed from the convex side. Neutral wedge osteotomy has no effect on final bone length. C: Closing wedge osteotomy. The CORA and correction axis lie on the concave cortex of the deformity. The cortex on the convex side of the deformity is compressed to restore alignment, requiring removal of a bone wedge across the entire bone diameter. A closing wedge osteotomy decreases final bone length.
A: Opening wedge osteotomy. The CORA and correction axis lie on the cortex on the convex side of the deformity. The cortex on the concave side of the deformity is distracted to restore alignment, opening an empty wedge that traverses the diameter of the bone. Opening wedge osteotomy increases final bone length. B: Neutral wedge osteotomy. The CORA and correction axis lie in the middle of the bone. The concave side cortex is distracted and the convex side cortex is compressed. A bone wedge is removed from the convex side. Neutral wedge osteotomy has no effect on final bone length. C: Closing wedge osteotomy. The CORA and correction axis lie on the concave cortex of the deformity. The cortex on the convex side of the deformity is compressed to restore alignment, requiring removal of a bone wedge across the entire bone diameter. A closing wedge osteotomy decreases final bone length.
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Figure 28-16
Wedge osteotomies; the osteotomy is made at the level of the CORA and the correction axis in all of these examples.
A: Opening wedge osteotomy. The CORA and correction axis lie on the cortex on the convex side of the deformity. The cortex on the concave side of the deformity is distracted to restore alignment, opening an empty wedge that traverses the diameter of the bone. Opening wedge osteotomy increases final bone length. B: Neutral wedge osteotomy. The CORA and correction axis lie in the middle of the bone. The concave side cortex is distracted and the convex side cortex is compressed. A bone wedge is removed from the convex side. Neutral wedge osteotomy has no effect on final bone length. C: Closing wedge osteotomy. The CORA and correction axis lie on the concave cortex of the deformity. The cortex on the convex side of the deformity is compressed to restore alignment, requiring removal of a bone wedge across the entire bone diameter. A closing wedge osteotomy decreases final bone length.
A: Opening wedge osteotomy. The CORA and correction axis lie on the cortex on the convex side of the deformity. The cortex on the concave side of the deformity is distracted to restore alignment, opening an empty wedge that traverses the diameter of the bone. Opening wedge osteotomy increases final bone length. B: Neutral wedge osteotomy. The CORA and correction axis lie in the middle of the bone. The concave side cortex is distracted and the convex side cortex is compressed. A bone wedge is removed from the convex side. Neutral wedge osteotomy has no effect on final bone length. C: Closing wedge osteotomy. The CORA and correction axis lie on the concave cortex of the deformity. The cortex on the convex side of the deformity is compressed to restore alignment, requiring removal of a bone wedge across the entire bone diameter. A closing wedge osteotomy decreases final bone length.
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When the CORA and correction axis lie on the convex cortex of the deformity, the correction will result in an opening wedge osteotomy (Fig. 28-16A). In an opening wedge osteotomy, the cortex on the concave side of the deformity is distracted to restore alignment, opening an empty, wedge-shaped space that traverses the diameter of the bone. An opening wedge osteotomy also increases bone length. 
When the CORA and correction axis lie in the middle of the bone, the correction distracts the concave side cortex and compresses the convex side cortex. A bone wedge is removed from the convex, compression side to allow realignment. This neutral wedge osteotomy (Fig. 28-16B) has no effect on bone length. 
When the CORA and correction axis lie on the concave cortex of the deformity, the correction will result in a closing wedge osteotomy (Fig. 28-16C). In a closing wedge osteotomy, the cortex on the convex side of the deformity is compressed to restore alignment; this requires removal of a bone wedge across the entire bone diameter. A closing wedge osteotomy decreases bone length (resulting in shortening). 
These principles of osteotomy also hold true when the osteotomy is located proximal or distal to the mutual site of the CORA and correction axis, except that realignment in these cases occurs via angulation and translation. When the CORA and correction axis are not at the same point and the osteotomy is proximal or distal to the CORA, the correction maneuver results in excess translation and an iatrogenic translational deformity. 

Dome Osteotomy

The type of dome osteotomy is also determined by the location of the CORA and the correction axis relative to the osteotomy. In contrast to a wedge osteotomy, however, the osteotomy site can never pass through the mutual CORA–correction axis (Fig. 28-17). Thus, translation will always occur with deformity correction using a dome osteotomy. 
Figure 28-17
In a dome osteotomy, the osteotomy site cannot pass through both the CORA and the correction axis.
 
Thus, translation will always occur when using a dome osteotomy. A: Ideally, the CORA and correction axis are mutually located with the osteotomy proximal or distal to that location such that the angulation and obligatory translation that occurs at the osteotomy site results in realignment of the bone axis. B: When the CORA and correction axis are not mutually located, a dome osteotomy through the CORA location results in a translational deformity.
Thus, translation will always occur when using a dome osteotomy. A: Ideally, the CORA and correction axis are mutually located with the osteotomy proximal or distal to that location such that the angulation and obligatory translation that occurs at the osteotomy site results in realignment of the bone axis. B: When the CORA and correction axis are not mutually located, a dome osteotomy through the CORA location results in a translational deformity.
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Figure 28-17
In a dome osteotomy, the osteotomy site cannot pass through both the CORA and the correction axis.
Thus, translation will always occur when using a dome osteotomy. A: Ideally, the CORA and correction axis are mutually located with the osteotomy proximal or distal to that location such that the angulation and obligatory translation that occurs at the osteotomy site results in realignment of the bone axis. B: When the CORA and correction axis are not mutually located, a dome osteotomy through the CORA location results in a translational deformity.
Thus, translation will always occur when using a dome osteotomy. A: Ideally, the CORA and correction axis are mutually located with the osteotomy proximal or distal to that location such that the angulation and obligatory translation that occurs at the osteotomy site results in realignment of the bone axis. B: When the CORA and correction axis are not mutually located, a dome osteotomy through the CORA location results in a translational deformity.
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Ideally, the CORA and correction axis are mutually located such that the angulation and obligatory translation that occurs at the osteotomy site results in realignment. Attempts at realignment when the CORA and correction axis are not mutually located results in a translational deformity (Fig. 28-17B). Similar to wedge osteotomy, the CORA and correction axis may lie on the cortex on the convex side of the deformity, on the cortex on the concave side of the deformity, or in the middle of the bone. 
The principles guiding wedge osteotomies hold true for dome osteotomies. When the CORA and correction axis lie on the convex cortex of the deformity, the correction will result in an opening dome osteotomy (Fig. 28-18). The translation that occurs in an opening dome osteotomy increases final bone length. When the CORA and correction axis lie in the middle of the bone, the correction will result in a neutral dome osteotomy. A neutral dome osteotomy has no effect on bone length. When the CORA and correction axis lie on the concave cortex of the deformity, the correction will result in a closing dome osteotomy. The translation that occurs in a closing dome osteotomy decreases final bone length. Unlike wedge osteotomies, the movement of one bone segment on the other with a dome osteotomy is rarely impeded, so removal of bone is not typically required unless the final configuration results in significant overhang of the bone beyond the aligned bone column. 
Figure 28-18
Dome osteotomies; the CORA and correction axis are mutually located with the osteotomy distal to that location in all of these examples.
 
A: Opening dome osteotomy. The CORA and correction axis lie on the cortex on the convex side of the deformity. An opening dome osteotomy increases final bone length. B: Neutral dome osteotomy. The CORA and correction axis lie in the middle of the bone. A neutral dome osteotomy has no effect on final bone length. C: Closing dome osteotomy. The CORA and correction axis lie on the concave cortex of the deformity. A closing dome osteotomy decreases final bone length and can result in significant overhang of bone that may require resection.
A: Opening dome osteotomy. The CORA and correction axis lie on the cortex on the convex side of the deformity. An opening dome osteotomy increases final bone length. B: Neutral dome osteotomy. The CORA and correction axis lie in the middle of the bone. A neutral dome osteotomy has no effect on final bone length. C: Closing dome osteotomy. The CORA and correction axis lie on the concave cortex of the deformity. A closing dome osteotomy decreases final bone length and can result in significant overhang of bone that may require resection.
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Figure 28-18
Dome osteotomies; the CORA and correction axis are mutually located with the osteotomy distal to that location in all of these examples.
A: Opening dome osteotomy. The CORA and correction axis lie on the cortex on the convex side of the deformity. An opening dome osteotomy increases final bone length. B: Neutral dome osteotomy. The CORA and correction axis lie in the middle of the bone. A neutral dome osteotomy has no effect on final bone length. C: Closing dome osteotomy. The CORA and correction axis lie on the concave cortex of the deformity. A closing dome osteotomy decreases final bone length and can result in significant overhang of bone that may require resection.
A: Opening dome osteotomy. The CORA and correction axis lie on the cortex on the convex side of the deformity. An opening dome osteotomy increases final bone length. B: Neutral dome osteotomy. The CORA and correction axis lie in the middle of the bone. A neutral dome osteotomy has no effect on final bone length. C: Closing dome osteotomy. The CORA and correction axis lie on the concave cortex of the deformity. A closing dome osteotomy decreases final bone length and can result in significant overhang of bone that may require resection.
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Treatment by Deformity Type

Length

Acute distraction or compression methods obtain immediate correction of limb length by acute lengthening with bone grafting or acute shortening, respectively. The extent of acute lengthening or shortening that is possible is limited by the soft tissues (soft tissue compliance, surgical and open wounds, and neurovascular structures). 
Acute distraction treatment methods involve distracting the bone ends to the appropriate length, placing a bone graft in the resulting space between the bone segments, and stabilizing the construct to allow incorporation of the graft. Options for treating length deformities include the use of: (1) autogenous cancellous or cortical bone grafts; (2) vascularized autografts; (3) bulk or strut cortical allografts; (4) mesh cage-bone graft constructs; and (5) synostosis techniques. A variety of internal and external fixation treatment methods may be used to stabilize the construct during graft incorporation.13 
The amount of shortening deformity that requires lengthening correction is uncertain.38,65,102 In the upper extremity, up to 3 to 4 cm of shortening is generally well tolerated, and restoring length when shortening exceeds this value has been reported to improve function.1,19,59,71,81,96,104,107 In the lower extremity, up to 2 cm of shortening may be treated with a shoe lift; tolerance for a 2- to 4-cm shoe lift is poor for most patients, and most patients with shortening of greater than 4 cm will benefit from restoration of bone length.7,8,31,64,102,109 
Acute compression methods are used to correct overdistraction deformities by first resecting the appropriate length of bone, approximating the bone ends, and then stabilizing the approximated bone ends under compression. For the paired bones of the forearm and leg, the unaffected bone requires partial excision to allow shortening and compression of the affected bone. For example, partial excision of the intact fibula is necessary to allow shortening and compression of the tibia. 
Gradual correction techniques for length deformities typically use tensioned-wire (Ilizarov) external fixation,5,16,51,59,60,62,73,102,104,107 although gradual lengthening techniques using conventional monolateral external fixation or a special intramedullary nail that provides a continuous lengthening force have been described.17,43,44,70,93,94 The most common form of gradual correction is gradual distraction to correct limb shortening. Gradual correction methods for length deformities can also be used to correct associated angular, translational, or rotational deformities simultaneously while restoring length. 
Gradual distraction involves the creation of a corticotomy (usually metaphyseal) and distraction of the bone segments at a rate of 1 mm per day using a rhythm of 0.25 mm of distraction repeated four times per day. The bone formed at the distraction site is formed through the process of distraction osteogenesis, as discussed below in the Ilizarov Techniques section. 

Angulation

Correction of angulation deformities involves making an osteotomy, obtaining realignment of the bone segments, and securing fixation during healing. The correction may be made acutely and then stabilized using a number of internal or external fixation methods.28,39 Alternatively, the correction may be made gradually using external fixation to both restore alignment and stabilize the site during healing.28,105 
Angulation deformities in the diaphysis are most amenable to correction using a wedge osteotomy at the same level as the correction axis and the CORA. For juxta-articular angulation deformities, however, the correction axis and the CORA may be located too close to the respective joint to permit a wedge osteotomy. Thus, juxta-articular angulation deformities may require a dome osteotomy with location of the osteotomy proximal or distal to the level of the correction axis and the CORA. 

Rotation

Correction of a rotational deformity requires an osteotomy and rotational realignment followed by stabilization. Stabilization may be accomplished using internal or external fixation following acute correction, or external fixation may be used to gradually correct the deformity. The appropriate level for the osteotomy, however, can be difficult to determine. While the level of the deformity is obvious in the case of an angulated malunion, the level of deformity in rotational limb deformities is often difficult to determine. Consequently, other factors, including muscle and tendon line of pull, and the location of neurovascular structures and soft tissues, are usually considered to determine the level of deformity and level of osteotomy for correction of a rotational deformity.32,56,57,78,80,101 

Translation

Translational deformities may be corrected in one of three ways. First, a single transverse osteotomy may be made to restore alignment through pure translation without angulation; the transverse osteotomy does not have to be made at the level of the deformity (Fig. 28-19). Second, a single oblique osteotomy may be made at the level of the deformity to restore alignment and gain length. Third, a translational deformity can be represented as two angulations with identical magnitudes but opposite directions. Therefore, two wedge osteotomies at the level of the respective CORAs and angular corrections of equal magnitudes in opposite directions may be used to correct a translational deformity. It should be noted that the osteotomy types used in this third method (opening, closing, or neutral) will affect final bone length. Internal or external fixation may be used to provide stabilization following acute correction of translational deformities, or gradual correction may be carried out using external fixation. 
Figure 28-19
 
A: A single transverse osteotomy to restore alignment through pure translation without angulation. B: A single oblique osteotomy at the level of the deformity to restore alignment and gain length. C: A translational deformity represented as two angulations with identical magnitudes but opposite directions causing malalignment of the mechanical axis of the lower extremity. In this case, two wedge osteotomies of equal magnitudes in opposite directions at the levels of the respective CORAs may be used to correct a translational deformity and restore alignment of the mechanical axis of the lower extremity.
A: A single transverse osteotomy to restore alignment through pure translation without angulation. B: A single oblique osteotomy at the level of the deformity to restore alignment and gain length. C: A translational deformity represented as two angulations with identical magnitudes but opposite directions causing malalignment of the mechanical axis of the lower extremity. In this case, two wedge osteotomies of equal magnitudes in opposite directions at the levels of the respective CORAs may be used to correct a translational deformity and restore alignment of the mechanical axis of the lower extremity.
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Figure 28-19
A: A single transverse osteotomy to restore alignment through pure translation without angulation. B: A single oblique osteotomy at the level of the deformity to restore alignment and gain length. C: A translational deformity represented as two angulations with identical magnitudes but opposite directions causing malalignment of the mechanical axis of the lower extremity. In this case, two wedge osteotomies of equal magnitudes in opposite directions at the levels of the respective CORAs may be used to correct a translational deformity and restore alignment of the mechanical axis of the lower extremity.
A: A single transverse osteotomy to restore alignment through pure translation without angulation. B: A single oblique osteotomy at the level of the deformity to restore alignment and gain length. C: A translational deformity represented as two angulations with identical magnitudes but opposite directions causing malalignment of the mechanical axis of the lower extremity. In this case, two wedge osteotomies of equal magnitudes in opposite directions at the levels of the respective CORAs may be used to correct a translational deformity and restore alignment of the mechanical axis of the lower extremity.
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Combined Deformities

Combined deformities are characterized by the presence of two or more types of deformity in a single bone.36,40 Treatment planning begins with identifying and characterizing each deformity independently from the other deformities. Once all deformities have been characterized, they are assessed as a group to determine which require correction to restore function. Correction of all of the deformities may be unnecessary. For example, small translational deformities or angulation deformities in the sagittal plane may not interfere with limb function and may remain untreated. Once those deformities requiring correction are identified, a treatment plan outlining the order and method of correction for each deformity can be developed. 
In many instances, a single osteotomy can be used to correct two deformities. For example, a combined angulation–translational deformity can be corrected using a single osteotomy at the level of the apex of the angulation deformity. This method restores alignment and congruency of the medullary canals and cortices of the respective bone segments (Fig. 28-20). The deformities are then reduced one at a time—reducing translation and then angulation, for instance. Consequently, stabilization can be achieved using an intramedullary nail (Fig. 28-21) or other internal fixation and external fixation methods. 
Figure 28-20
A single osteotomy to correct an angulation–translational deformity.
 
A: A single osteotomy is made to allow correction of both deformities. B: Correction of the translational deformity, followed by (C) correction of the angulation deformity, resulting in realignment.
A: A single osteotomy is made to allow correction of both deformities. B: Correction of the translational deformity, followed by (C) correction of the angulation deformity, resulting in realignment.
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Figure 28-20
A single osteotomy to correct an angulation–translational deformity.
A: A single osteotomy is made to allow correction of both deformities. B: Correction of the translational deformity, followed by (C) correction of the angulation deformity, resulting in realignment.
A: A single osteotomy is made to allow correction of both deformities. B: Correction of the translational deformity, followed by (C) correction of the angulation deformity, resulting in realignment.
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Figure 28-21
 
A: AP radiograph of a 50-year-old woman with a femur fracture sustained in a motor vehicle accident 28 years ago. The left femur has a 12-degree varus deformity with 23 mm of lateral translation. B: AP radiograph showing acute correction using a single osteotomy and statically locked intramedullary nail fixation. C: AP radiograph showing final deformity correction and solid union 8 months after surgery. Nail dynamization was performed 5 months after the corrective osteotomy.
A: AP radiograph of a 50-year-old woman with a femur fracture sustained in a motor vehicle accident 28 years ago. The left femur has a 12-degree varus deformity with 23 mm of lateral translation. B: AP radiograph showing acute correction using a single osteotomy and statically locked intramedullary nail fixation. C: AP radiograph showing final deformity correction and solid union 8 months after surgery. Nail dynamization was performed 5 months after the corrective osteotomy.
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Figure 28-21
A: AP radiograph of a 50-year-old woman with a femur fracture sustained in a motor vehicle accident 28 years ago. The left femur has a 12-degree varus deformity with 23 mm of lateral translation. B: AP radiograph showing acute correction using a single osteotomy and statically locked intramedullary nail fixation. C: AP radiograph showing final deformity correction and solid union 8 months after surgery. Nail dynamization was performed 5 months after the corrective osteotomy.
A: AP radiograph of a 50-year-old woman with a femur fracture sustained in a motor vehicle accident 28 years ago. The left femur has a 12-degree varus deformity with 23 mm of lateral translation. B: AP radiograph showing acute correction using a single osteotomy and statically locked intramedullary nail fixation. C: AP radiograph showing final deformity correction and solid union 8 months after surgery. Nail dynamization was performed 5 months after the corrective osteotomy.
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Combined angulation–translational deformities can also be treated as multiapical angulation deformities with an osteotomy through either or both CORAs in the frontal and sagittal planes. While this method restores alignment of the bone’s mechanical axis, it can also result in incomplete bone-to-bone contact and incongruence of the medullary canals of the bone segments and cortices. As a result, stabilization cannot be achieved using an intramedullary nail and other internal fixation and external fixation methods are required to stabilize the bone segments. 
A combined angulation–rotational deformity can be corrected by a single rotation of the distal segment around an oblique axis that represents the resolutions of both the component angulation axis and the rotation axis (Fig. 28-22).66 The direction and magnitude of the combined angulation–rotational deformity are both characterized in this oblique axis. The angle of the oblique correction axis, which is perpendicular to the plane of the necessary osteotomy, can be approximated using trigonometry (axis angle = tan−1[rotation/angulation]; orientation of plane of osteotomy = 90 – axis angle). 
Figure 28-22
 
A: Combined angulation-rotational deformity with a 20-degree angulation deformity and a 30-degree rotational deformity. Calculations of the correction axis show an inclination of 56 degrees, which corresponds to an osteotomy inclination of 34 degrees. B: The 34-degree osteotomy is made such that it passes through the CORA of the angulation deformity. C: Rotation of 36 degrees about the correction axis in the plane of the osteotomy results in realignment by simultaneous correction of both deformities.
A: Combined angulation-rotational deformity with a 20-degree angulation deformity and a 30-degree rotational deformity. Calculations of the correction axis show an inclination of 56 degrees, which corresponds to an osteotomy inclination of 34 degrees. B: The 34-degree osteotomy is made such that it passes through the CORA of the angulation deformity. C: Rotation of 36 degrees about the correction axis in the plane of the osteotomy results in realignment by simultaneous correction of both deformities.
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Figure 28-22
A: Combined angulation-rotational deformity with a 20-degree angulation deformity and a 30-degree rotational deformity. Calculations of the correction axis show an inclination of 56 degrees, which corresponds to an osteotomy inclination of 34 degrees. B: The 34-degree osteotomy is made such that it passes through the CORA of the angulation deformity. C: Rotation of 36 degrees about the correction axis in the plane of the osteotomy results in realignment by simultaneous correction of both deformities.
A: Combined angulation-rotational deformity with a 20-degree angulation deformity and a 30-degree rotational deformity. Calculations of the correction axis show an inclination of 56 degrees, which corresponds to an osteotomy inclination of 34 degrees. B: The 34-degree osteotomy is made such that it passes through the CORA of the angulation deformity. C: Rotation of 36 degrees about the correction axis in the plane of the osteotomy results in realignment by simultaneous correction of both deformities.
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This single osteotomy is made at a location such that it passes through the level of the CORA of the angulation deformity (i.e., the bisector of the axes of the proximal and distal segments). Rotation of the distal segment about this CORA in the plane of the osteotomy results in realignment; opening and closing wedge corrections can also be achieved by using the CORA located on the respective cortex. Rotation of the distal segment in the plane of the osteotomy but not about a CORA will lead to a secondary translational deformity. This secondary deformity can be corrected by reducing the translation after rotation is completed. Locating the level of the osteotomy distal to the level of the CORA and correcting the secondary translational deformity can be used to correct a combined deformity if locating the osteotomy at the level of the CORA is impractical, such as would occur if the osteotomy would violate a growth plate or place soft tissues or neurovascular structures at risk. 

Treatment by Deformity Location

The bone involved and the specific bone region or regions (e.g., epiphysis, metaphysis, diaphysis) define the anatomic location. While a bone-by-bone discussion is beyond the scope of this chapter, we will address the influence of the anatomic regions of long bones on the treatment of malunions in general terms. 

Shaft

Diaphyseal deformities involve primarily cortical bone in the central section of long bones. Characterizing deformities is straightforward, as angulation and translational deformities are usually obvious on plain radiographs. In addition, the use of wedge osteotomies through the CORA for deformity correction is generally achievable, thus allowing reduction of the deformity without concerns about inducing secondary translational deformities. By virtue of their relatively homogeneous morphology, diaphyseal deformities are amenable to a wide array of fixation methods following correction. Intramedullary nail fixation is preferable when practical (Fig. 28-23). 
Figure 28-23
 
A, B: AP and lateral radiographs on presentation of a 37-year-old man initially definitively treated in traction in Africa for a femoral shaft fracture. C, D: AP and lateral radiographs following deformity correction with closed antegrade femoral nailing.
A, B: AP and lateral radiographs on presentation of a 37-year-old man initially definitively treated in traction in Africa for a femoral shaft fracture. C, D: AP and lateral radiographs following deformity correction with closed antegrade femoral nailing.
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Figure 28-23
A, B: AP and lateral radiographs on presentation of a 37-year-old man initially definitively treated in traction in Africa for a femoral shaft fracture. C, D: AP and lateral radiographs following deformity correction with closed antegrade femoral nailing.
A, B: AP and lateral radiographs on presentation of a 37-year-old man initially definitively treated in traction in Africa for a femoral shaft fracture. C, D: AP and lateral radiographs following deformity correction with closed antegrade femoral nailing.
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Periarticular

Periarticular deformities located in the metaphysis and epiphysis are more difficult to identify, characterize, and treat. In addition to the juxta-articular deformities of length, angulation, rotation, and translation and the presence of joint malorientation, there may also be malreduction of articular surfaces and compensatory joint deformities, such as soft tissue contractures and fixed joint subluxation or dislocation. Identification, characterization, and prioritization of each component are critical to forming a successful treatment plan. 
Acute correction of periarticular deformities is most often accomplished using plate and screw fixation or external fixation. Gradual correction may also be accomplished using external fixation particularly for small periarticular bone segments (Fig. 28-24). 
Figure 28-24
 
A: Presenting AP radiograph of a 45-year-old woman with a malunited distal tibial fracture. This pure frontal plane deformity measured 21 degrees of varus with a CORA located 21 mm proximal to the distal tibial joint orientation line. B: AP radiograph following transverse osteotomy and during gradual deformity correction (differential lengthening) using a Taylor Spatial Frame. C: Final AP radiograph following deformity correction and bony consolidation.
A: Presenting AP radiograph of a 45-year-old woman with a malunited distal tibial fracture. This pure frontal plane deformity measured 21 degrees of varus with a CORA located 21 mm proximal to the distal tibial joint orientation line. B: AP radiograph following transverse osteotomy and during gradual deformity correction (differential lengthening) using a Taylor Spatial Frame. C: Final AP radiograph following deformity correction and bony consolidation.
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Figure 28-24
A: Presenting AP radiograph of a 45-year-old woman with a malunited distal tibial fracture. This pure frontal plane deformity measured 21 degrees of varus with a CORA located 21 mm proximal to the distal tibial joint orientation line. B: AP radiograph following transverse osteotomy and during gradual deformity correction (differential lengthening) using a Taylor Spatial Frame. C: Final AP radiograph following deformity correction and bony consolidation.
A: Presenting AP radiograph of a 45-year-old woman with a malunited distal tibial fracture. This pure frontal plane deformity measured 21 degrees of varus with a CORA located 21 mm proximal to the distal tibial joint orientation line. B: AP radiograph following transverse osteotomy and during gradual deformity correction (differential lengthening) using a Taylor Spatial Frame. C: Final AP radiograph following deformity correction and bony consolidation.
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Treatment by Method

Plate and Screw Fixation

The advantages of plate and screw fixation include rigidity of fixation; versatility for various anatomic locations and situations (e.g., periarticular deformities); correction of deformities under direct visualization; and safety following failed or temporary external fixation. Disadvantages of the method include extensive soft tissue dissection; limitation of early weight-bearing and function; and inability to correct significant shortening deformity. A variety of plate types and techniques is available, and these are presented in the chapters covering specific fracture types. In cases of deformity correction with poor bone-to-bone contact following reduction; however, other methods of skeletal stabilization should be considered. 
Locking plates have screws with threads that lock into threaded holes on the corresponding plate. This locking effect creates a fixed-angle device, or “single-beam” construct, because no motion occurs between the screws and the plate.15,24,42 In contrast to traditional plate-and-screw constructs, the locked screws resist bending moments and the construct distributes axial load across all of the screw-bone interfaces.24,42 As compared to compression plating where healing is by direct osteonal bridging, locked plating performed without compression results in healing via callus formation.24,48,79,95,110 Due to the inherent axial and rotational stability with locked devices, obtaining contact between the plate and the bone is unnecessary; the construct can be thought of as functioning similarly to an external fixator but being located within the body. Consequently, periosteal damage and microvascular compromise are minimal. Locking plates are considerably more expensive than traditional plates and should be used primarily in deformity cases that are not amenable to traditional plate-and-screw fixation.15 

Intramedullary Nail

Intramedullary nail fixation is particularly useful in the lower extremity because of the strength and load-sharing characteristics of intramedullary nails. This method of fixation is ideal for cases where diaphyseal deformities are being corrected (Fig. 28-25). The method may also be useful for deformities at the metaphyseal–diaphyseal junction. Intramedullary implants are excellent for osteopenic bone where screw purchase may be poor. 
Figure 28-25
 
A, B: AP and lateral 51-inch alignment radiographs of a 52-year-old woman with a painful total knee arthroplasty. This patient had severe arthrofibrosis, severe pain, and had failed revision total knee arthroplasty. She was referred in for a knee fusion but was noted to have an oblique plane angular malunion of her proximal femur from a prior fracture, as indicated by the white lines superimposed on the femur. It was felt that without correction of this femoral malunion, passage of the knee fusion nail through the angled femoral diaphysis would have been difficult and the final clinical and functional results would likely have been suboptimal due to malalignment of the mechanical axis of the lower extremity. C, D: Follow-up radiographs 5 months after operative treatment with resection of her total knee arthroplasty, percutaneous corticotomy of her proximal femur to correct her deformity, and percutaneous antegrade femoral nailing to stabilize the corticotomy site and stabilize her knee fusion site.
A, B: AP and lateral 51-inch alignment radiographs of a 52-year-old woman with a painful total knee arthroplasty. This patient had severe arthrofibrosis, severe pain, and had failed revision total knee arthroplasty. She was referred in for a knee fusion but was noted to have an oblique plane angular malunion of her proximal femur from a prior fracture, as indicated by the white lines superimposed on the femur. It was felt that without correction of this femoral malunion, passage of the knee fusion nail through the angled femoral diaphysis would have been difficult and the final clinical and functional results would likely have been suboptimal due to malalignment of the mechanical axis of the lower extremity. C, D: Follow-up radiographs 5 months after operative treatment with resection of her total knee arthroplasty, percutaneous corticotomy of her proximal femur to correct her deformity, and percutaneous antegrade femoral nailing to stabilize the corticotomy site and stabilize her knee fusion site.
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Figure 28-25
A, B: AP and lateral 51-inch alignment radiographs of a 52-year-old woman with a painful total knee arthroplasty. This patient had severe arthrofibrosis, severe pain, and had failed revision total knee arthroplasty. She was referred in for a knee fusion but was noted to have an oblique plane angular malunion of her proximal femur from a prior fracture, as indicated by the white lines superimposed on the femur. It was felt that without correction of this femoral malunion, passage of the knee fusion nail through the angled femoral diaphysis would have been difficult and the final clinical and functional results would likely have been suboptimal due to malalignment of the mechanical axis of the lower extremity. C, D: Follow-up radiographs 5 months after operative treatment with resection of her total knee arthroplasty, percutaneous corticotomy of her proximal femur to correct her deformity, and percutaneous antegrade femoral nailing to stabilize the corticotomy site and stabilize her knee fusion site.
A, B: AP and lateral 51-inch alignment radiographs of a 52-year-old woman with a painful total knee arthroplasty. This patient had severe arthrofibrosis, severe pain, and had failed revision total knee arthroplasty. She was referred in for a knee fusion but was noted to have an oblique plane angular malunion of her proximal femur from a prior fracture, as indicated by the white lines superimposed on the femur. It was felt that without correction of this femoral malunion, passage of the knee fusion nail through the angled femoral diaphysis would have been difficult and the final clinical and functional results would likely have been suboptimal due to malalignment of the mechanical axis of the lower extremity. C, D: Follow-up radiographs 5 months after operative treatment with resection of her total knee arthroplasty, percutaneous corticotomy of her proximal femur to correct her deformity, and percutaneous antegrade femoral nailing to stabilize the corticotomy site and stabilize her knee fusion site.
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Ilizarov Techniques

Ilizarov techniques36,9,10,12,21,23,26,33,37,39,46,5155,61,72,73,81,84,85,104,105 have many advantages, including that they: (1) are primarily percutaneous, minimally invasive, and typically require only minimal soft tissue dissection; (2) can promote the generation of osseous tissue; (3) are versatile; (4) can be used in the presence of acute or chronic infection; (5) allow for stabilization of small intra-articular or periarticular bone fragments; (6) allow simultaneous deformity correction and enhancement of bone healing3,5,6,11,13,37,50,55; (7) allow immediate weight bearing and early joint function; (8) allow augmentation or modification of the treatment as needed through frame adjustment; and (9) resist shear and rotational forces while the tensioned wires allow the “trampoline effect” (axial loading–unloading) during weight-bearing activities. 
The Ilizarov external fixator can be used to reduce and stabilize virtually any type of deformity, including complex combined deformities (Fig. 28-26), and restore limb length in cases of limb shortening. A variety of treatment modes can be employed using the Ilizarov external fixator, including distraction lengthening, and multiple sites in a single bone can be treated simultaneously. Monofocal lengthening involves a single site undergoing distraction. Bifocal lengthening denotes that two lengthening sites exist (Fig. 28-27). 
Figure 28-26
 
(A) AP and (B) lateral radiographs of a 25-year-old man 2 years after fracture of humerus while arm wrestling. This oblique plane deformity has 30 degrees AP varus, 21 degrees lateral posterior apex, and 5 mm of axial shortening, using the contralateral humerus as a reference. C: Ilizarov gradual deformity correction in progress. (D) AP and (E) lateral radiograph showing final deformity correction and solid bony union of the osteotomy site.
(A) AP and (B) lateral radiographs of a 25-year-old man 2 years after fracture of humerus while arm wrestling. This oblique plane deformity has 30 degrees AP varus, 21 degrees lateral posterior apex, and 5 mm of axial shortening, using the contralateral humerus as a reference. C: Ilizarov gradual deformity correction in progress. (D) AP and (E) lateral radiograph showing final deformity correction and solid bony union of the osteotomy site.
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Figure 28-26
(A) AP and (B) lateral radiographs of a 25-year-old man 2 years after fracture of humerus while arm wrestling. This oblique plane deformity has 30 degrees AP varus, 21 degrees lateral posterior apex, and 5 mm of axial shortening, using the contralateral humerus as a reference. C: Ilizarov gradual deformity correction in progress. (D) AP and (E) lateral radiograph showing final deformity correction and solid bony union of the osteotomy site.
(A) AP and (B) lateral radiographs of a 25-year-old man 2 years after fracture of humerus while arm wrestling. This oblique plane deformity has 30 degrees AP varus, 21 degrees lateral posterior apex, and 5 mm of axial shortening, using the contralateral humerus as a reference. C: Ilizarov gradual deformity correction in progress. (D) AP and (E) lateral radiograph showing final deformity correction and solid bony union of the osteotomy site.
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Figure 28-27
Bifocal lengthening.
 
A: Tibia with length deformity showing two corticotomy sites. B: Tibia following distraction osteogenesis at both corticotomy sites showing restoration of length.
A: Tibia with length deformity showing two corticotomy sites. B: Tibia following distraction osteogenesis at both corticotomy sites showing restoration of length.
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Figure 28-27
Bifocal lengthening.
A: Tibia with length deformity showing two corticotomy sites. B: Tibia following distraction osteogenesis at both corticotomy sites showing restoration of length.
A: Tibia with length deformity showing two corticotomy sites. B: Tibia following distraction osteogenesis at both corticotomy sites showing restoration of length.
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Distraction Lengthening

The bone formed at the corticotomy site in distraction lengthening Ilizarov treatment occurs by distraction osteogenesis (Fig. 28-28).3,4,20,51,67 Distraction produces a tension-stress effect that causes neovascularity and cellular proliferation in many tissues, including bone regeneration primarily through intramembranous bone formation. Corticotomy and distraction osteogenesis result in profound biologic stimulation. For example, Aronson6 reported a nearly 10-fold increase in blood flow following corticotomy and lengthening at the proximal tibia distraction site relative to the control limb in dogs as well as increased blood flow in the distal tibia. 
Figure 28-28
Regenerate bone (arrows) at the corticotomy site is formed via distraction osteogenesis.
 
A: Monofocal lengthening of the tibia. B: Bifocal lengthening of the humerus.
A: Monofocal lengthening of the tibia. B: Bifocal lengthening of the humerus.
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Figure 28-28
Regenerate bone (arrows) at the corticotomy site is formed via distraction osteogenesis.
A: Monofocal lengthening of the tibia. B: Bifocal lengthening of the humerus.
A: Monofocal lengthening of the tibia. B: Bifocal lengthening of the humerus.
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A variety of mechanical and biologic factors affect distraction osteogenesis. First, the corticotomy or osteotomy must be performed using a low-energy technique to minimize necrosis. Second, distraction of the metaphyseal or metaphyseal–diaphyseal regions has superior potential for regenerate bone formation relative to diaphyseal sites. Third, the external fixator construct must be very stable. Fourth, a latency period of 7 to 14 days following the corticotomy and before beginning distraction is recommended. Fifth, since the formation of the bony regenerate is slower in some patients, the treating physician should monitor the progression of the regenerate on plain radiographs and adjust the rate and rhythm of distraction accordingly. Sixth, a consolidation phase in which external fixation continues in a static mode following restoration of length that generally lasts two to three times as long as the distraction phase is required to allow maturation and hypertrophy of the regenerate. 

Complex Combined Deformities

All bone deformities can be characterized by describing the position of one bone segment relative to another in terms of angular rotations in each of three planes and linear displacements along each of three axes. Complex deformities can be characterized using magnitudes for each of these six parameters. Directions of the rotations or displacements are defined as positive and negative relative to the anatomic position. Positive rotations are defined by the right-hand rule: With the thumb pointed in the positive direction along the respective axis (defined identically to the displacement descriptions), the curled fingers indicate the direction of positive rotation (Fig. 28-29). For example, angulation in the frontal plane is rotation about an anterior–posterior axis. With anterior defined as the positive direction for this axis, counterclockwise rotation (to an examiner who is face to face with the patient) is positive and clockwise rotation is negative. Anterior, right, and superior displacements are defined as positive values. 
Figure 28-29
Definitions used to characterize complex deformities using three angular rotations and three linear displacements.
Rockwood-ch028-image029.png
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Complex combined deformities often require gradual correction to allow adaptation of not only the bone but also the surrounding soft tissues and neurovascular structures. The modern Ilizarov hardware system uses different components (hinges, threaded rods, rotation–translation boxes) to achieve correction of multiple deformity types in a single bone. Alternatively, the Taylor Spatial Frame (Fig. 28-30), which uses six telescopic struts, can be used to correct complex combined deformities.2,2527,29,58,62,63,68,69,8387,97,98,103,106,108,111,112 A computer program is used in treatment planning to determine strut lengths to connect the rings for the original frame construction around the deformity. The rings of the external fixator frame are attached perpendicular to the respective bone segments and the struts are gradually adjusted to attain neutral frame height (i.e., rings in parallel). Any residual deformity is then corrected by further adjusting the struts. 
Figure 28-30
 
A: Taylor Spatial Frame with rings placed obliquely to one another and in parallel with the position of the tibial angular–translation deformity. B: Taylor Spatial Frame following correction of the deformity by adjusting the six struts to attain neutral frame height (i.e., rings in parallel).
A: Taylor Spatial Frame with rings placed obliquely to one another and in parallel with the position of the tibial angular–translation deformity. B: Taylor Spatial Frame following correction of the deformity by adjusting the six struts to attain neutral frame height (i.e., rings in parallel).
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Figure 28-30
A: Taylor Spatial Frame with rings placed obliquely to one another and in parallel with the position of the tibial angular–translation deformity. B: Taylor Spatial Frame following correction of the deformity by adjusting the six struts to attain neutral frame height (i.e., rings in parallel).
A: Taylor Spatial Frame with rings placed obliquely to one another and in parallel with the position of the tibial angular–translation deformity. B: Taylor Spatial Frame following correction of the deformity by adjusting the six struts to attain neutral frame height (i.e., rings in parallel).
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Correction can be simultaneous, in which all deformities are corrected at the same time, or sequential, in which some deformities (e.g., angulation–rotation) are corrected before others (e.g., translations). The rate at which correction occurs must be determined on a patient-by-patient basis and depends on the type and magnitude of deformity, the potential effects on the soft tissues, the health and healing potential of the patient, and the balance between premature consolidation and inadequate regenerate formation. 

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