Hip Joint-preserving Surgery for the Mature Hip: the Children’s Hospital Experience

Most osteoarthritis of the hip is associated with chronic abnormal hip mechanics,1 related to potentially treatable anatomic abnormalities.2 The rationale of mechanically-based measures to prevent or treat osteoarthrosis assumes the following: (a) the correctable mechanical abnormality is a major etiologic factor in osteoarthrosis; (b) relief of the mechanical abnormality can prevent or improve osteoarthrosis; and (c) joint-preserving measures in the individual patient are preferable to joint replacement. Our evolving experience3 and that of other centers with similar interests suggests that the success of such mechanically-based joint-preserving measures depends largely on two important factors: (a) the degree to which the joint-preserving treatment normalizes the mechanical environment of the hip and (b) the amount of irreversible articular damage that is present at the inception of the joint-preserving treatment. For many years, classical realignment osteotomy of the dysplastic acetabulum has been well accepted as being effective in improving on the natural history of congruous acetabular dysplasia. Realignment osteotomies with the proximal femur similarly have an accepted place in treating the symptomatic patient with a severe healed slipped capital femoral epiphysis.4 Until recently, the predominant picture of abnormal hip mechanics was a largely static one, derived from Pauwels and others. In 1991, the Berne group first described the acetabular rim syndrome as a clinical presentation of dysplasia of the hip.5 This led to a more generalized recognition of pathologic loading of the acetabular rim as an early major factor in hip arthrosis of various types. Follow-up has revealed that the rim loading by the femoral head in acetabular dysplasia involves instability, a major pathomechanical agent. Conversely, an equally important pathomechanical factor, impingement,6 leads to a very different but equally malignant type of rim loading in Perthes disease, slipped epiphysis, and a number of other previously less well-recognized anatomic variants that include femoral retroversion, coxa vara, reduced femoral head-neck offset, coxa profunda, and protrusio. As the pathomechanics of the hip have become better understood, new diagnostic and therapeutic methods have yielded very satisfying early results in both understanding and treating many symptomatic hips that only a few years ago were relegated unhappily to the idiopathic osteoarthritis category, often left to deteriorate on their own, to await the inevitable hip replacement when symptoms became intolerable. The discussion of joint-preserving treatment around the hip may be subdivided into two broad categories: (a) dysplasia and (b) hip impingement syndromes.