Other Conditions of the Hip
Matthew B. Dobbs
José A. Morcuende
COXA VARA
Definition.
Coxa vara is defined as any decrease in the femoral neck-shaft angle below the normal. Coxa vara was initially classified by Elmslie (1). This classification has subsequently been modified by Fairbank and condensed into three broad categories: congenital coxa vara, acquired coxa vara, and developmental coxa vara (2) (Table 26-1).
Congenital coxa vara is characterized by a primary cartilaginous defect in the femoral neck. This can be a congenital short femur, a congenital bowed femur, or part of a proximal femoral focal deficiency (PFFD) (Fig. 26-1). The deformity is not always evident clinically at birth; however, it is usually evident on radiographs (3, 4). Significant leg length inequality is often present.
Acquired coxa vara can be caused by a number of conditions including trauma (Fig. 26-2), infection, pathologic bone disorders (Fig. 26-3), slipped capital femoral epiphysis, and Legg-Calvé-Perthes disease (LCPD). The resulting coxa vara can be secondary to necrosis of the femoral head or altered physeal growth. Coxa vara can also be associated with skeletal dysplasias and, although these conditions probably should be classified separately, they are included under “acquired causes” for the sake of simplicity (5, 6, 7 and 8) (Fig. 26-4).
Developmental coxa vara is a term reserved for coxa vara of the proximal femur in early childhood, with classical radiographic changes and no other skeletal manifestations or obvious underlying causes (9, 10) (Fig. 26-5). There is associated mild limb-length inequality that develops secondary to the progressive varus deformity, but not because of a significant decrease in the length of the femoral shaft. The growth behavior and radiographic changes help differentiate this condition from the others mentioned previously.
Epidemiology.
Developmental coxa vara is a rare entity, with a reported incidence of 1 in 25,000 live births worldwide (10, 11). The ratio of boys to girls is 1:1, and there do not seem to be any major racial predilections (12, 13). The rate of occurrence in the left and right hips is also equal. The condition is bilateral in 30% to 50% of patients (10, 12, 14, 15, 16, 17 and 18). Bilateral cases may more likely be associated with a skeletal dysplasia, so the examiner should investigate for this possibility during the physical and radiographic examination. There is presumed to be a genetic predilection for developmental coxa vara, with several reports suggesting an autosomal dominant pattern of inheritance with incomplete penetrance (10, 13, 17, 18, 19 and 20).
Etiology.
The exact cause of developmental coxa vara remains unknown. The most widely accepted theory is that the deformity in the proximal femur results from a primary defect in endochondral ossification of the medial part of the femoral neck (21). This results in dystrophic bone along the medial inferior aspect of the femoral neck, which fatigues with weight bearing, resulting in the progressive varus deformity that is seen clinically. In this regard, the condition has been likened to infantile Blount disease of the proximal tibia; however, the two conditions have not been shown to coexist (22, 23).
Other investigators hypothesize that the varus deformity is caused by excessive intrauterine pressure on the developing fetal hip, resulting in a depression in the neck of the femur (9). A vascular insult causing a growth arrest to the developing femoral head and neck has also been proposed as a cause of coxa vara (24). Yet another theory is that the varus deformity results from faulty maturation of the cartilage and metaphyseal bone of the femoral neck (10).
Clinical Features.
The child with developmental coxa vara usually presents after he or she has started walking and
before 6 years of age (25, 26). Clinically, the child presents with a painless limp that is caused by both the functional abductor muscle weakness and a relatively minor limb-length inequality in unilateral cases. When the disease is bilateral, the child presents with a waddling gait and increased lumbar lordosis as seen in bilateral developmental hip dislocation (2, 10, 25, 27, 28 and 29). Although pain is seldom reported as a symptom, older children may report a deep ache in the buttock muscles after prolonged exercise.
before 6 years of age (25, 26). Clinically, the child presents with a painless limp that is caused by both the functional abductor muscle weakness and a relatively minor limb-length inequality in unilateral cases. When the disease is bilateral, the child presents with a waddling gait and increased lumbar lordosis as seen in bilateral developmental hip dislocation (2, 10, 25, 27, 28 and 29). Although pain is seldom reported as a symptom, older children may report a deep ache in the buttock muscles after prolonged exercise.
TABLE 26-1 Classification of Coxa Vara | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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On physical examination, the greater trochanter will be more prominent and proximal than the contralateral normal side, thereby altering normal hip joint mechanics. With increasing coxa vara deformity, the origin and insertion of the hip abductors approach each other, resulting in functional hip abductor weakness and a positive Trendelenburg test. An associated limblength inequality is present in unilateral cases but is rarely >3 cm at skeletal maturity, even in untreated patients (13, 30).
The range of motion of the hip is reduced in all planes of motion, with limitations of abduction and internal rotation being the greatest (12, 25). The limitation in abduction is due to impingement of the greater trochanter on the side of the pelvis. The loss of internal rotation is due to the loss of the femoral neck anteversion that is a feature of developmental coxa vara. As part of the general clinical examination, other causes of coxa vara should be ruled out, for example, skeletal dysplasias (15, 31).
Radiographic Features.
The diagnosis of developmental coxa vara is confirmed with a plain anteroposterior radiograph of the affected hip. The typical radiographic findings are listed in Table 26-2. Mild acetabular dysplasia is sometimes present as well (4, 10, 15, 16, 21, 26, 31, 32). The inverted Y pattern seen in the inferior femoral neck remains the sine qua non of this condition. The inverted Y pattern is formed by a triangular piece of bone in the medial femoral neck, abutting the physis and bounded by two radiolucent bands (Fig. 26-6). Although these bands were once postulated to be two physeal plates, biopsy specimens and magnetic resonance studies have shown this to be an area of widening of the physeal plate with associated abnormal ossification (22). Kim et al. used computed tomography (CT) scanning in three patients and suggested that the triangular metaphyseal fragment is a Salter-Harris type 2 “separation” through the defective femoral neck (32).
The amount of varus deformity of an affected hip may be quantified on anteroposterior radiographs by measuring the neck-shaft angle, the head-shaft angle, or the Hilgenreinerepiphyseal angle (H-E) (33). Neither the neck-shaft angle nor the head-shaft angle provides an accurate reflection of the severity of the deformity and its likely progression or correction (24, 29). On the other hand, the H-E angle, described by Weinstein, has been shown to have good prognostic value (33). The H-E angle is the angle between the physeal plate and Hilgenreiner line (33) (Fig. 26-6). In 100 healthy patients, this angle averaged 16 degrees. In developmental coxa vara, the angle is between 40 and 70 degrees. Using this measurement in 22 patients with coxa vara, Weinstein was able to make recommendations concerning the natural history and treatment options for this group of children. These are discussed in the subsequent text.
Pathoanatomy.
In early fetal development, the proximal femoral physis extends across the entire proximal femur. The cartilage columns that make this physis then differentiate into cervical epiphyseal and trochanteric apophyseal portions. The medial cervical portion matures first, elongating the femoral neck. The neck-shaft angle is determined by the relative amount of growth at these two sites (34, 35, 36, 37 and 38). The mean angle of the femoral neck-shaft angle is 150 degrees at 3 weeks of age, decreasing to 120 degrees in adulthood (39) (Fig. 26-7).
A number of reports have been published on biopsies taken from both the proximal femoral physis and femoral neck in patients with developmental coxa vara (12, 34, 40). These have shown defects in cartilage production and secondary metaphyseal bone formation in the inferior portion of the proximal femoral physeal plate and adjacent femoral neck. The cartilage cell numbers are decreased and the remaining cells are not well organized in regular columns as seen in a healthy physis. The adjacent metaphyseal bone is osteoporotic and infiltrated with nests of cartilage cells (34, 40) (Fig. 26-8). Chung and Riser reported on the postmortem findings in a 5-year-old boy with unilateral coxa vara. They noted that the acetabular volume and femoral head
were smaller, the femoral neck was shorter, and the physis was wider on the affected side than on the normal contralateral side. They found that endochondral ossification was altered in the affected hip as well as in the “normal” contralateral side. They also observed that there was a “reduction in the number and caliber of intraosseous arteries supplying the metaphyseal sides of the growth plates in the proximal femur and those supplying the subchondral region and extraosseous medial ascending cervical arteries on the surface of the femoral neck” (34).
were smaller, the femoral neck was shorter, and the physis was wider on the affected side than on the normal contralateral side. They found that endochondral ossification was altered in the affected hip as well as in the “normal” contralateral side. They also observed that there was a “reduction in the number and caliber of intraosseous arteries supplying the metaphyseal sides of the growth plates in the proximal femur and those supplying the subchondral region and extraosseous medial ascending cervical arteries on the surface of the femoral neck” (34).
 FIGURE 26-1. Natural history radiographically of a child with congenital coxa vara and congenital short femur. A: Radiographic appearance of a 9-month-old girl at presentation with unilateral coxa vara and congenital short femur. B: The same patient at 2 years of age showing progression in femoral shortening and varus deformity. C: Patient at 5 years of age with increased shortening and coxa vara deformity. |
The resulting deformity is a combination of the underlying pathology and the altered mechanical forces across the hip. With progressive varus deformity of the femoral neck, the force across the proximal femoral physis changes from compression to shear as it assumes a more vertical orientation. The shortened lever arm and relative proximal migration of the greater trochanter also leads to altered muscular forces in the abductor group.
Natural History.
Untreated developmental coxa vara was once viewed as a condition in which increased tensile forces on the superior femoral neck led to progressive varus deformity of the proximal femur, ultimately resulting in the development of a stress-fracture-related nonunion of the femoral neck and premature degenerative arthritic changes within the hip joint in almost all the affected patients (41). Weinstein et al. (33), however, showed that not all patients with developmental coxa vara follow such a progressive course. Their study demonstrated that the determining factor for progression of the varus deformity is the H-E angle. If the H-E angle is <45 degrees, the condition is stable and progressive deformity is unlikely. If the H-E angle is >60 degrees, surgical intervention is recommended because the deformity invariably progresses. Between 45 and 60 degrees, the natural history is not as clear, and these patients must have serial radiographs to reevaluate their varus deformity (33). Serafin et al. (16), Carroll et al. (22), Cordes et al. (23), and Desai et al. (15) have all confirmed these parameters in their own patient populations. What is not clear from natural history studies is the time of onset of developmental coxa vara and the speed of progression of the deformity.
Treatment Recommendations.
The treatment algorithm for developmental coxa vara is based on the natural history studies mentioned in the preceding text. Because the cause of the abnormal pathology is not known, a biologic cure is not
possible. Treatment, therefore, is aimed at preventing the secondary deformities of the proximal femur created by the condition’s natural history. Borden et al. (42) identified the main objectives of current treatment approaches: correction of the varus angulation into a more normal physiologic range; changing the loading characteristics seen by the abnormal femoral neck from shear to compression; correction of limb-length inequality; and reestablishment of a proper abductor muscle length-tension relation.
possible. Treatment, therefore, is aimed at preventing the secondary deformities of the proximal femur created by the condition’s natural history. Borden et al. (42) identified the main objectives of current treatment approaches: correction of the varus angulation into a more normal physiologic range; changing the loading characteristics seen by the abnormal femoral neck from shear to compression; correction of limb-length inequality; and reestablishment of a proper abductor muscle length-tension relation.
 FIGURE 26-2. The radiographic appearance of acquired coxa vara in a 7-year-old girl who had an intertrochanteric left hip fracture. |
Nonsurgical.
Patients who have an H-E angle of <45 degrees and are asymptomatic need to be assessed for limblength inequality (in unilateral cases) and for evidence of skeletal dysplasia. These patients should also have periodic radiographic assessments to assess for progressive deformity until skeletal maturity. In patients with an H-E angle between 45 and 59 degrees, serial radiographs are essential so as to assess for progression. In those who develop a symptomatic limp, Trendelenburg gait, or progressive deformity, surgical treatment is warranted. In general, nonsurgical treatments including bed rest, traction, and hip immobilization in a spica cast have not altered the natural course of the disease (24, 29, 43). Zadek (21), in a review of conservative treatment of developmental coxa vara, concluded that the previously attempted nonoperative methods had universally little or no value.
 FIGURE 26-3. The radiographic appearance of acquired coxa vara in an 8-year-old child who had fibrous dysplasia and a shepherd-crook deformity of the proximal femur. |
 FIGURE 26-4. The radiographic appearance of coxa vara associated with cleidocranial dysostosis in a 4-year-old child. |
 FIGURE 26-5. Radiographic appearance of developmental coxa vara in a 3-year-old child. |
Surgical
Indications.
Options.
A variety of surgical treatments have been recommended for developmental coxa vara over the years, many of which are of historical interest only One such procedure is epiphysiodesis of the greater trochanter, which has been shown to be unreliable as the sole surgical treatment of this condition (12, 27, 45). Other historical surgical procedures included pin fixation and bone grafting of the femoral neck defect, which did not correct the varus deformity, did not prevent progression, and sometimes resulted in growth arrest of the capital femoral physis (27).
Valgus Osteotomy for Developmental Coxa Vara.
The most successful way to correct the deformity and restore more normal hip joint mechanics is with a rotational valgus-producing proximal femoral osteotomy (Figs. 26-9, 26-10, 26-11, 26-12, 26-13, 26-14, 26-15, 26-16 and 26-17). A valgus osteotomy converts the shear forces across the physis into compressive forces, and this appears to improve ossification in the femoral neck. Correction of the neck-shaft angle to normal also restores the muscle function to the hip abductors. Restoration of a normal neck-shaft angle allows proximal femoral remodeling and normal ossification to occur. The proximal femoral osteotomy has been performed at the level of the neck, the intertrochanteric region, and the subtrochanteric region, all with the goal of restoring the normal anatomy of the hip joint (2, 12, 29, 42, 44, 46, 47, 48, 49, 50 and 51). Femoral neck osteotomies have had a higher morbidity rate and poorer clinical results than either the intertrochanteric or subtrochanteric
osteotomies, which are the treatments of choice (14, 15, 22, 23, 31, 33, 52, 53 and 54). Many intertrochanteric and subtrochanteric osteotomies have been described for correcting coxa vara, thereby indicating that no one method has proved to be totally satisfactory. Langenskiöld valgus-producing osteotomy (12) (Fig. 26-18) and Pauwel Y-shaped osteotomy (23, 55) (Fig. 26-19) are examples of intertrochanteric corrective osteotomies that have produced good results. Pauwel osteotomy is technically demanding and does not allow rotational correction of the upper femur. Borden et al. (42) describe a subtrochanteric valgus-producing osteotomy that has been used successfully in achieving and maintaining the goals of surgical treatment (Fig. 26-20).
osteotomies, which are the treatments of choice (14, 15, 22, 23, 31, 33, 52, 53 and 54). Many intertrochanteric and subtrochanteric osteotomies have been described for correcting coxa vara, thereby indicating that no one method has proved to be totally satisfactory. Langenskiöld valgus-producing osteotomy (12) (Fig. 26-18) and Pauwel Y-shaped osteotomy (23, 55) (Fig. 26-19) are examples of intertrochanteric corrective osteotomies that have produced good results. Pauwel osteotomy is technically demanding and does not allow rotational correction of the upper femur. Borden et al. (42) describe a subtrochanteric valgus-producing osteotomy that has been used successfully in achieving and maintaining the goals of surgical treatment (Fig. 26-20).
TABLE 26-2 Radiographic Features of Developmental Coxa Vara | |||||
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 FIGURE 26-6. Hilgenreiner-epiphyseal (H-E) angle. A: The H-E angle is the angle between Hilgenreiner line and a line drawn parallel to the capital femoral physis. Note the inverted Y pattern formed by the triangular piece of bone in the medial femoral neck. B: H-E angle of 68 degrees in a patient with developmental coxa vara. |
 FIGURE 26-7. Evolution of the neck-shaft angle in the normal hip. |
 FIGURE 26-8. Photomicrograph of a biopsy specimen of the proximal femoral physeal plate of a patient with developmental coxa vara demonstrates irregularly distributed germinal cells in the resting zone; an absence of normal, orderly progression of the cartilage columns; and a poorly defined zone of provisional calcification. Nests of cartilage cells reside at the margin of the metaphyseal bone. |
A difficult decision to make is the timing of the osteotomy. Some orthopaedists advocate performing the osteotomy as soon as it is clinically indicated, whereas others prefer to wait until the child is older. Pylkkanen (12), Weighill (47), and Serafin (52) recommend that the osteotomy be performed at an early age, even as young as 18 months. Weinstein et al. (33), and Duncan (10), on the other hand, recommend delaying surgery until the patient is 5 to 6 years of age. In very young children, it is difficult to obtain adequate fixation because of the mostly cartilaginous proximal femur, and this may accentuate the propensity for recurrence of the deformity in this age group. On the other hand, the amount of acetabular dysplasia associated with developmental coxa vara most likely increases with increasing age, and the capacity for acetabular remodeling decreases with increasing age. Therefore, the appropriate time for surgical intervention in indicated patients is as soon as there is adequate bone development to allow secure internal fixation.
The proximal femoral redirectional osteotomy is performed with the patient in the supine position on a radiolucent table. The proximal femur is approached laterally with subperiosteal exposure obtained. The transverse intertrochanteric osteotomy is performed with an oscillating power saw with subperiosteal retractors protecting the medial soft-tissue structures. Location of the osteotomy is verified with use of a C-arm. The amount of varus correction necessary to achieve recreation of the pathologic vertical orientation of the proximal femoral physis is typically >30 degrees. In performing the proximal femoral varus correcting osteotomy, the location of the osteotomy relative to the attachment of the psoas tendon should be considered. Performing the osteotomy proximal to the lesser trochanter facilitates varus correction but in larger patients and/or severe deformity the intact attachment of the psoas tendon to the proximal fragment makes it more
difficult to achieve both satisfactory correction of the varus deformity and relative lateral displacement of the distal fragment. Performing the osteotomy just distal to the lesser trochanter makes it relatively easier to displace the distal fragment laterally. However, the necessary valgus tilting of the proximal fragment may potentiate near abutment of its distal medial edge against the pelvis. When performing a valgus-producing osteotomy, it is often desirable to lateralize the distal fragment. Aligning the shaft of the distal fragment with piriformis fossa of the proximal fragment helps to assure a correct medial/lateral relationship of the two osteotomy fragments. If excessive medialization is noted, either slightly withdrawing the
blade from the proximal fragment or changing to an implant with a longer blade will help to achieve more lateralization. If alternatively relative excessive lateralization of the distal fragment is noted, the blade plate needs to be driven further into the proximal fragment and/or an implant with a shorter blade should be used.
difficult to achieve both satisfactory correction of the varus deformity and relative lateral displacement of the distal fragment. Performing the osteotomy just distal to the lesser trochanter makes it relatively easier to displace the distal fragment laterally. However, the necessary valgus tilting of the proximal fragment may potentiate near abutment of its distal medial edge against the pelvis. When performing a valgus-producing osteotomy, it is often desirable to lateralize the distal fragment. Aligning the shaft of the distal fragment with piriformis fossa of the proximal fragment helps to assure a correct medial/lateral relationship of the two osteotomy fragments. If excessive medialization is noted, either slightly withdrawing the
blade from the proximal fragment or changing to an implant with a longer blade will help to achieve more lateralization. If alternatively relative excessive lateralization of the distal fragment is noted, the blade plate needs to be driven further into the proximal fragment and/or an implant with a shorter blade should be used.
Valgus Osteotomy for Developmental Coxa Vara (Figs. 26-9, 26-10, 26-11, 26-12, 26-13, 26-14, 26-15, 26-16 and 26-17)
 FIGURE 26-9. Valgus Osteotomy for Developmental Coxa Vara. The Pauwels osteotomy (53) is planned to place the physis perpendicular to the direction of the resultant compressive forces (16 degrees off the horizontal), eliminating the shearing forces. In addition, the diaphysis is used to enlarge the proximal end of the femoral neck. The osteotomy does not allow for correction of rotation. The planning of the osteotomy is similar to planning for other osteotomies. A radiograph centered on the femoral head and in the proper degree of rotation is used for the tracing. First, the proximal femur and its axis, the acetabulum, and the physis are outlined on tracing paper. Three lines should be drawn on this outline. First, a horizontal line is drawn several centimeters below the lesser trochanter and perpendicular to the femoral shaft (H). Second, a line is drawn through the physis intersecting H (PS). Third, a line is drawn 16 degrees from the horizontal H line. This will place the physis at 16 degrees, which is perpendicular to the direction of the resultant compressive force. The angle formed by this third line and PS is the size of the wedge to be removed for correction. In this illustration this is 50 degrees. |
 FIGURE 26-10. The upper cut of the osteotomy is now drawn so that it reaches the physis in what Pauwels called the region of resorption. The inferior cut is then marked so that it intersects the upper cut at a point that leaves a portion of the diaphysis equal in width to the width of the triangular fragment. |
 FIGURE 26-11. Finally, the inferior portion of the osteotomy with the femoral axis is traced on a separate piece of paper (A). This paper is now superimposed on the first sheet and rotated so that the osteotomy lines on the two papers come together (B). The femoral axes now form a 50-degree angle. The upper fragment of the osteotomy is now traced on this second sheet. This second sheet is now rotated back and slid upward, keeping the femoral axes parallel. When the femoral head lies in the acetabulum, it is traced on this second sheet, giving the result of the osteotomy (C). |
 FIGURE 26-12. The patient is placed either on a translucent table top or on a fracture table, depending on the child’s size and the surgeon’s preference. The femur is exposed as previously described. Kirschner wires are placed under image intensifier control to mark the lines of the osteotomy (A). The wedge of bone is removed with a power saw. It is easier to make the proximal cut first, leaving the medial cortex intact. The inferior cut is made and the wedge removed (B). Finally, the proximal cut is completed. |
 FIGURE 26-13. A: A bone hook is now placed over the top of the trochanter. The trochanter and the proximal fragment are pulled down and laterally to displace the proximal fragment onto the diaphysis. The leg is abducted to close the osteotomy. B: Fixation can be by any method of the surgeon’s choice. In our limited experience, two Kirschner wires are passed from the proximal fragment into the distal fragment, combined with a spica cast, works well in smaller children. These Kirschner wires may be combined with a tension band wire for added fixation. In larger children, a blade plate works well. |
 FIGURE 26-14. Amstutz and Wilson (44) discussed the various methods for correction of coxa vara, the difficulty in obtaining and maintaining the desired amount of correction, and the reasons. They thought that in the absence of good fixation in young children, an interlocking osteotomy with a long spike of cortical bone from the distal fragment mortised into a slot in the proximal fragment was best. Some cases required that the spike be placed across the physis and into the femoral head. Mobilization of the fragments was difficult, requiring adductor tenotomy, release of the abductor muscles, and subperiosteal stripping. Occasionally, Kirschner wire fixation was added. All these patients were treated in abduction with a spica cast. |
 FIGURE 26-15. Plykkanen (56) described an osteotomy attributed to Langenskiold. In this procedure, an intertrochanteric osteotomy is performed at the level of the triangular fragment. The distal fragment is abducted so that the lateral shaft of the distal fragment lies adjacent to the cut surface of the proximal fragment. The two fragments may be fixed with cerclage wires, Kirschner wires, or tension band wires. |
 FIGURE 26-16. In the older child, the osteotomy can be accomplished with an angled blade plate as described by Borden et al. (49). For the child, the plate will either have to be custom made or have to be made by bending an available device. This may also be done with some of the newer pediatric screws and plate combinations provided that the plate permits a sufficient amount of valgus. It is often necessary to cross the physis to gain sufficient purchase on the proximal fragment. After the plate is seated, a subtrochanteric osteotomy is performed. With traction and abduction of the leg, the plate is brought into contact with the femoral shaft and secured with a clamp and then with screws. To achieve abduction of the distal fragment, an adductor tenotomy may be necessary (6). To complete the osteotomy without increasing the pressure on the hip joint, it may also be necessary to remove a portion of the distal fragment or a wedge from the lateral aspect of the proximal fragment. |
 FIGURE 26-17. A: Anteroposterior radiograph of a child with bilateral developmental coax vara. |
 FIGURE 26-17. (continued) B: Immediately after bilateral femoral osteotomies using the technique of Amstutz in a plaster cast. C: Eighteen months later, more horizontal growth plates are apparent along with the remodeling of the proximal femur. |
 FIGURE 26-18. Langenskiöld intertrochanteric osteotomy. A: Site of osteotomy in proximal femur. B: After osteotomy with fixation in place and resulting coxa valga. |
 FIGURE 26-19. Pauwel Y-shaped osteotomy. A: Lines are drawn corresponding to the axes of the physis (P) and parallel to Hilgenreiner line several centimeters below the lesser trochanter (H). The angle between lines P and H, less 16 degrees (the normal Hilgenreiner-epiphyseal angle), describes the amount of deformity and therefore the angle of wedge to be resected (in this case, 44 degrees). B: Proximal femur after the wedge of bone has been removed. |
 FIGURE 26-19. (continued) C: Proximal femur with osteotomy completed and hardware in place. |
 FIGURE 26-20. Borden subtrochanteric osteotomy. A: Line of osteotomy and insertion of 140-degree angle blade plate parallel to the superior border of the femoral neck. B: Varus deformity corrected. Note that the lateral cortex of the proximal fragment is approximated to the upper end of the distal fragment. |
In addition to obtaining correction of the varus, often the distal fragment should be internally rotated to correct preoperatively noted external rotation (proximal femoral retroversion). The amount of derotation required is a clinical decision made during surgery. If there is an adductor contracture, an adductor tenotomy performed at the time of the valgus osteotomy will make it easier to obtain satisfactory varus correction (51). Similarly, at times, shortening the proximal or distal fragment will make it easier to reduce the two fragments and obtain adequate valgus tilt of the proximal fragment (25). Care should be taken to avoid crossing the physeal plate with the fixation device, if possible.
Fixation with an intermediate rigid blade plate optimizes the resultant inherent stability of the construct. In younger children and/or those with less bone mass, an alternative form of internal fixation suggested by Wagner is performed with a bifurcated plate driven through the intramedullary surface of the proximal fragment and secured to the distal fragment with screws (Fig. 26-21). A number of other devices have been used, including cerclage wire (53), hook plates (54), and external fixators (55), all of which have a higher incidence of fixation failure.
The goal of surgical treatment is to produce a valgus overcorrection of the neck-shaft angle of the proximal femur, regardless of the patient’s age. A number of authors have reported recurrence rates of between 30% and 70% because of insufficient correction at the time of surgery, or loss of correction in the postoperative period because of inadequate fixation of the osteotomy (15, 22, 23). Carroll et al. (22)
found that if the H-E angle is reduced to <38 degrees, 95% of the patients showed no evidence of recurrence (Fig. 26-22). In contrast, 93% of the osteotomies that retained a physeal angle >40 degrees required revision for recurrent varus deformity.
found that if the H-E angle is reduced to <38 degrees, 95% of the patients showed no evidence of recurrence (Fig. 26-22). In contrast, 93% of the osteotomies that retained a physeal angle >40 degrees required revision for recurrent varus deformity.
 FIGURE 26-21. Internal fixation of valgus osteotomy with the Wagner bifurcated plate. The bifurcated end of the plate is driven into the proximal fragment through its intramedullary surface. |
 FIGURE 26-22. Anteroposterior pelvic radiographs of a 4-year-old child with developmental coxa vara. A: Preoperative radiograph. B: Postoperative radiograph. A subtrochanteric derotational proximal femoral osteotomy successfully achieved the objectives of surgical correction, including correction of the varus angulation, restoring the Hilgenreiner-epiphyseal (H-E) angle to <30 degrees, and lateralizing the distal fragment to help reestablish the proper abductor muscle length-tension relation. |
Successful treatment results in maintenance of the valgus correction and restoration of more normal growth of the proximal physis. By converting the shear stresses to compression, the osteotomy allows this more normal development. The triangular metaphyseal defect in the femoral neck spontaneously closes within the first months postoperatively in most cases, if adequate valgus has been created (25) (Fig. 26-23). The results of most studies show that a correction of the H-E angle to <40 degrees will result in a good clinical outcome. The published results of valgus osteotomies for coxa vara invariably include multiple etiologies for this deformity; hence, some conclusions are not necessarily specific for developmental coxa vara. In a review of 14 patients who had had a Pauwel Y-shaped intertrochanteric osteotomy for coxa vara, Cordes et al. (23) reported good maintenance of correction at 11 years average follow-up in patients in whom the H-E angle had been corrected to <40 degrees. Desai and Johnson (15) reviewed 20 hips in 12 patients for an average of 20 years and found that satisfactory results were achieved if the H-E angle was 35 degrees or less. Twelve hips had trochanteric overgrowth; however, only five of these patients had weakness of the abductor. Yang and Huang (50) showed that the acetabular depth improves significantly in patients with developmental coxa vara who are
treated with a valgus intertrochanteric osteotomy, especially if it is performed before the child reaches 6 years of age. Carroll et al. (22) reviewed 37 affected hips in 26 children following a valgus osteotomy for congenital or acquired coxa vara. They reported a 50% recurrence rate that was unrelated to age at the time of surgery, the type of internal fixation, or the etiology. Of the children in whom the H-E angle was corrected to <38 degrees, 95% had no recurrence of the deformity. If the femoral osteotomy is performed before 10 years of age, 83% of the patients will have excellent acetabular development (Fig. 26-24).
treated with a valgus intertrochanteric osteotomy, especially if it is performed before the child reaches 6 years of age. Carroll et al. (22) reviewed 37 affected hips in 26 children following a valgus osteotomy for congenital or acquired coxa vara. They reported a 50% recurrence rate that was unrelated to age at the time of surgery, the type of internal fixation, or the etiology. Of the children in whom the H-E angle was corrected to <38 degrees, 95% had no recurrence of the deformity. If the femoral osteotomy is performed before 10 years of age, 83% of the patients will have excellent acetabular development (Fig. 26-24).
 FIGURE 26-23. Anteroposterior pelvic radiographs of a child with developmental coxa vara. A: The preoperative radiograph demonstrates a classic inferior femoral neck triangular fragment. B: Two months postoperatively, the radiograph demonstrates correction of the physeal angle, with spontaneous closure of the femoral neck triangular metaphyseal fragment. |
 FIGURE 26-24. The anteroposterior pelvic radiographs of an 8-year-old child with developmental coxa vara. A: Preoperative radiograph. B: The postoperative radiograph 11 months after the subtrochanteric proximal femoral derotational osteotomy and fixation with a sliding hip screw demonstrates spontaneous closure of the proximal femoral epiphyseal plate. The greater trochanteric apophyses remain open. |
Authors’ Preferred Recommendations.
The important first step in treating developmental coxa vara is to rule
out any other possible cause for this condition (Table 26-1). Once diagnosed, the child should be followed up every 4 to 6 months with anteroposterior radiographs of the pelvis. Surgical intervention is recommended for hips with an H-E angle of 60 degrees or greater, a progressive decrease in the femoral neck-shaft angle of 90 to 100 degrees or less, or in patients with developmental coxa vara who develop a symptomatic limp or Trendelenburg gait. The authors prefer an intertrochanteric valgus-producing, and, as appropriate, rotational osteotomy of the proximal femur. The preferred fixation device is an adolescent size blade plate (130-degree angle). For larger adolescent patients, the adult size 130-degree blade plate is used. For small and/or young patients, the modified Wagner plate (Fig. 26-23) and supplemented spica cast is preferred. An adductor tenotomy is performed if contracture of the adductor muscles limits passive hip motion. If an adductor tenotomy is performed in conjunction with the valgus osteotomy, an abducting wedge-shaped foam pillow is utilized for comfort for the first 3 to 4 weeks postoperatively. Following a valgus-producing osteotomy, bone overgrowth of the fixation device is likely. The authors recommend surgically removing the implant 1 to 2 years following healing of the osteotomy.
out any other possible cause for this condition (Table 26-1). Once diagnosed, the child should be followed up every 4 to 6 months with anteroposterior radiographs of the pelvis. Surgical intervention is recommended for hips with an H-E angle of 60 degrees or greater, a progressive decrease in the femoral neck-shaft angle of 90 to 100 degrees or less, or in patients with developmental coxa vara who develop a symptomatic limp or Trendelenburg gait. The authors prefer an intertrochanteric valgus-producing, and, as appropriate, rotational osteotomy of the proximal femur. The preferred fixation device is an adolescent size blade plate (130-degree angle). For larger adolescent patients, the adult size 130-degree blade plate is used. For small and/or young patients, the modified Wagner plate (Fig. 26-23) and supplemented spica cast is preferred. An adductor tenotomy is performed if contracture of the adductor muscles limits passive hip motion. If an adductor tenotomy is performed in conjunction with the valgus osteotomy, an abducting wedge-shaped foam pillow is utilized for comfort for the first 3 to 4 weeks postoperatively. Following a valgus-producing osteotomy, bone overgrowth of the fixation device is likely. The authors recommend surgically removing the implant 1 to 2 years following healing of the osteotomy.
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