Transarticular Stabilization of the Immature Femoral Head

Abstract

Acetabular dysplasia and hip instability are common in neuromuscular diseases such as spina bifida and cerebral palsy due to deranged muscle function around the hip. Occasionally in developmental dysplasia of the hip, persistent instability may be difficult to manage by standard treatments. It is in these contexts that we wished to investigate whether a dislocatable hip could be stabilized by means of a transarticular suture acting as a reconstructed ligamentum teres. The aim of this study was to investigate and assess the iatrogenic damage caused by such a procedure on the immature proximal femoral physis, epiphysis, and hip joint. Four- to 6-week-old mixed breed European pigs (n = 18) were used in the study. Six animals with normal hips underwent the stabilization procedure to the right hip joint, the left hips serving as controls. The remaining 12 pigs were subjected to a model of hip dysplasia on the right hip. After 6 weeks, the dysplasia stimulus was removed, and half of the animals underwent the hip stabilization procedure, the remaining 6 animals served as a control for "untreated dysplasia." Animals underwent serial pelvic radiography until euthanasia at 18 weeks of age. Postoperative, morphometric, radiographic, and histological analyses were performed. The dysplasia model consistently produced an increase in the acetabular index, femoral head subluxation, and growth retardation of the capital epiphysis. We observed no detrimental effect on the capital ossific nucleus, proximal femoral physis, or acetabular development in terms of radiographic, morphometric, or histological findings after the transarticular suture procedure. The surgical technique of drilling across the immature porcine hip did not result in avascular necrosis of the femoral head, osseous bar formation across the proximal femoral physis, proximal femoral metaphyseal growth disturbance, chondrolysis, or disturbance in normal acetabular development. The described technique may be a useful augment to the definitive stabilization of the recalcitrant dysplastic or unstable hip where standard operative measures alone are likely to be unsuccessful.