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Reconstruction of Residual Deformities of the Hip
A New Surgical Option
Vassilios A. Papavasiliou, MD; and John M. Kirkos, MD
Paediatric Orthopaedic Department, Aristotle University of Thessaloniki, Thessaloniki, Greece.
John M. Kirkos, MD, 138, AI. Papanastasiou Str, Thessaloniki 54249, Greece.
(Η εργασία έχει πρωτοδημοσιευθεί στο CLINICAL ORTHOPAEDICS AND RELATED REASEARCH,Number 341,pp 123-127,1997)
Shortening of the femoral neck and relative overgrowth of the greater trochanter are the main problems after avascular necrosis of the capital femoral epiphysis. A new type of femoral osteotomy was performed in 16 patients to lengthen the femoral neck, improve the biomechanics of the hip joint with better congruity of the heat, and to restore the leg length discrepancy. Clinical and radiologic follow-up showed good results in all the patients after a mean time of 4.3 years. Relief of pain, a negative Trendelenburg sing, and improvement of hip movements, particularly abduction, were the most significant short term results.
Ischemic necrosis of the femoral head is one of the most devastating complications that can arise in the treatment of congenital hip dislocation, Perthes disease, or septic arthritis. The necrosis may either involve the entire capital growth plate of the femur or be limited to one side, causing a general or localized growth retardation of the femoral neck, respectively. Central and total necrosis of the physis retard growth of the femoral neck. As a result, the femoral neck remains short with a marked relative overgrowth of the greater trochanter, impingement, and shortening of the entire limb.
Numerous surgical techniques have been proposed to manage the femoral neck shortening and greater trochanter overgrowth secondary to avascular necrosis of the capital femoral epiphysis with little success. 2,4 - 7.9.10
The present report describes an operative technique that provides elongation of the femoral neck, biomechanical improvement of the joint, congruity of the femoral head, and equalization of the leg lenhth discrepancy.
MATERIALS AND METHODS
Clinical Material
Sixteen patients suffering from growth retardation of the femoral neck were treated surgically as described below. Eleven patients suffered from cequelae of congenital dislocation of the hip and five from sequelae of Perthes disease. The left hip was affected in nine patients and the right in seven patients. Ten were male and six were female, with ages ranging from 14 to 19 years (mean, 15.5 years).
Preoperatively, the major clinical complaint was hip pain and limping. The affected limb was shorter by as many as 3 cm in all the patients. Flexion contractures of the hip were not observed in any patient, but significant restriction of internal rotation by approximately 50, with slight pain, was present in all. Abduction was also limited to 1/3 of normal, probably because of the trochanteric impingement. The Trendelenburg sign was positive in all cases.
Radiographic evaluation showed a short femoral neck with elevation of the greater trochanter and a relatively shallow acetabulum on anteroposterior (AP) radiographs.
Operative Technique
The hip was exposed through a lateral incision approximately 10 cm in length from the tip of the greater trochanter and extending distally. After soft dissection and periosteal elevation, a specially designed four-hole plate was placed on the exposed lateral surface of the femur and fixed distally with two screws (Fig 1A-B).
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Fig 1A-G. Drawing showing the operative technique used in this study.
(A) Short femoral neck with marked relative overgrowth of the greater trochanter and shortening of the entire limb.
(B) Fixation of the plate on the lateral side of the femur with two distal screws.
(C) L type osteotomy of the femur (dotted line).
(D) Gradual distraction of the osteotomy.
(E) With further distraction into abduction, the distraction of the ostetomy itself moves the lower fragment into adduction, while the mobile femoral head goes deeper into the socket.
(F) The engagement of the femoral cortic anteriorly or posteriorly restores the anteversion of the femoral neck to a proper degree.
(G) The two proximal screws secure the entire procedure.
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The trochanteric fossa was identified and a sagittal osteotomy was performed with an oscillating saw down the middle of the longitudinal femoral axis until 3 mm above the proximal screw. Then a horizontal osteotomy was done to unite the medial cortical surface with the distal end of the longitudinal osteotomy (Fig 1C).
A nonself compression plate with the distance between the two central holes ranging from 3.5 cm to 6 cm in 0.5-cm es- calations, was used. The plate was bent preoperatively to adapt it to the normal shape of the lateral surface of the proximal femur. After the L shaped osteotomy was mobilized, a distractor was inserted in its horizontal plane. Significant force was not required for the first 1.5 to 2 cm of distraction of the osteotomy because of soft tissue relaxation (Fig 1D). With further distraction, the mobile femoral head rotated deeper into the acetabulum as the entire upper fragment moved gradually into abduction as a result of the increased resistance of the soft tissues (Fig 1E). Concurrently, the greater trochanter moved laterally and distally.
Because of this automatic rotation of the femoral head into the acetabulum during distraction, the two surfaces that underwent osteotomy advanced into an C shape (Fig 1F-G) anteriorly or posteriorly. With this, the entine procedure also corrected any rotational deformity. The final position was secured by the insertion of the two proximal screws. The wound was closed in layers and a hip spica cast was permitted 2 months posteoperatively.
RESULTS
The mean follow-up was to 4.3 years, ranging from 3 to 7 years. The 3-cm leg length discrepancy measured preoperatively was corrected by the 1-year postoperative follow-up in all patients. In addition, none of the patients complained of pain on walking. At 1-year follow-up, the Trendelenburg sign was negative in 10 of the 16 patients.
The remaining six patients had a positive Trendelenburg sign until the second postoperative year. Internal and external rotation with the hip in flexion were increased in all patients as high as 200. Abduction was almost normal ( Fig 2).
Fig 2A-D Radiographs of a 16-year-old girl with hip dysplasia.
(A) Shortening of the femoral neck and relative overgrowth of the greater trochanter after late conservative treatment of congenital hip dislocation.
Fig 2A-D Radiographs of a 16-year-old girl with hip dysplasia.
(B) An L type osteotomy was performed.
(C) The radiologic appearance qo months postoperatively.
Fig 2A-D Radiographs of a 16-year-old girl with hip dysplasia.
(D) The result 4 years postoperatively.
DISCUSSION
Although various procedures exist to treat patients with congenital hip dislocation or Perthes disease, residual deformities often persist that remain difficult to solve. These include leg length discrepancy, hip joint incongruity, proximal displacement of the greater trochanter, and poor joint biomechanics. The procedure describer in the present report provides an adequate solution to the most paramount of these problems by ensuring elongation of the femoral neck, biomechanical improvement of the joint, congruity of the femoral head, and equalization of the log length discreapancy.
Residual deformities have been managed by a distal transfer of the greater trochanter using its base as a graft with extensive internal fixation,11 and by a distal and lateral transfer of the greater trochanter.3 Although these methods attempt to improve the hip joint biomechanically, they ignore the correction of leg length discrepancy and the congruity of the hip joint.
It is well established that a varus configuration of the neck shaft angle is more stable that is a valgus configuration. The greater the anteversion, the less stable the femoral head is within the acetabulum. In this regard, a reduction in the anteversion of the femur justifiably is considered a means of enhancing stability. In many cases, the greater trochanteric physis, which is usually not damaged, continues to grow, leading to a relatively upward displacement of the greater trochanter. As a result, the functional effectiveness of the abductors is compreomised, resulting in a progressively worsening Trendelenburg gait.
A distal transfer of the trochanter, so that the uppermost tip comes to lie directly opposite the center of the femoral head, will restore a more normal biomechanical relationship and often can reverse the positive Treandelenburg sign. In some situations, it may be necessary to lateralize the greater trochanter. 11
The surgical procedure described in the present study not only provided limb equalization but also repositioned the greater trochanter to its normal level (Fig 3). In addition, the method described ensures elongation of the femoral neck with subsequent restoration of the gluteus medius length. Moreover, the engagement of the femoral cortices anteriorly or posteriorly during the distraction restores the anteversion of the femoral neck to a proper degree. Another advantage of the desvribed operation is provided by the reorientation of the femoral head deeper into the acetabulum, which improves the contact between the articular surfaces.
Fig 3A-B Radiographs of a 16-year-old with hip dysplasia.
(A) Shortening of the femoral neck and relative overgrowth of the greater trochanter after Perthes disease.
(B) The result 6 years postoperatively. The prominent notch (arrow) is a remainder of the base of the femoral neck.
Because of the compression force between the mobile head and the stable socket during distraction, the type of osteotomy used in the study may seem to risk ischemic necrosis of the head. However, this complication has not been observed in any of the patients in this series.
Delayed union was not observed despite the distraction and the lateral displacement of the greater trochanter. Rather, callus formation appeared throughout the osteotomy gap within 3 to 4 weeks. Even though the osteosynthesis was not rigid, the cortical engagement, the extensive surface of the osteotomy, and the hip spica secure the entire procedure.
Foyr radiographic patterns of ischemic necrosis of the proximal part of the femur are caused by the morphologic changes in the capital femoral epiphysis, the physis, and the proximal femoral metaphysis.1,8 The L shaped osteotomy described in this study can be performed in all four patterns of necrosis.
Although the number of the patients surgically treated by the described procedure is limited and the follow-up period short, the early results are promising. Specifically, Trendelenburg gait and leg length discrepancy are satisfactorily managed. In addition, the procedure increases the range of hip motion and the strength of hip abduction, and provides pain relief and improved gait and endurance. Thus, the new surgical procedure described in this report satisfactorily treats patients with residual deformities from congenital hip disease or Perthes disease, as seen by the results.
REFERENCES
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