compartments of the knee simply by altering the way they walk and can avoid loading the patellofemoral joint in flexion. The hip, as a unicompartmental joint, cannot be as selectively unloaded.
Villar, in a preliminary report, described 60% improvement among patients undergoing arthroscopy for osteoarthritis.52 Glick et al. reported only 34% patient satisfaction among patients with degenerative disease followed for a minimum of 2 years.53 In a subsequent study of labral lesions, good results were reported in only 21% of patients when there was coexistent arthritis.26 In our prospective study of patients with 5-year follow-up, 50% of those with arthritis demonstrated significant improvement at 2 years, and this diminished to 35% at 5-year follow-up.12 Although the statistical success rate is not encouraging, some patients have continued to do remarkably well.
Harris et al. were the first to report inversion of the acetabular labrum as a cause of osteoarthritis (Figure 2.12).30 More recently, we have reported on osteoarthritis due to an inverted labrum that can occur with and without accompanying acetabular dysplasia.31 The cardinal radiographic feature is superolateral joint space narrowing (Figure 2.13). This condition has been implicated in cases that experience acute exacerbation of symptoms despite chronic radiographic findings and has also been identified in cases which demonstrate rapid radiographic evidence of joint space loss (Figure 2.14). The results of arthro-scopic debridement in this condition are no better than the results reported for other causes of arthritis, but recognizing the radiographic features may help avoid a more extensive, and unnecessary, workup when the symptoms seem poorly explained by the radiographic findings. In this condition, the articular de-
FIGURE 2.13. The cardinal radiographic feature of osteoarthritis due to an inverted labrum is superolateral joint space narrowing. (A) Narrowing of the superolateral joint space creates a convergence laterally of the normally parallel lines created by the radius of curvature of the subchondral bone of the acetabulum and the convex surface of the femoral head. (B) Another method of visually interpreting narrowing of the joint space is that the arc created by the radius of curvature of the acetabulum intersects the femoral head. (C) Secondary features of osteoarthritis including osteophyte formation are present, but the cardinal radiographic feature of asymmetric superolateral joint space narrowing is also evident. (From Byrd and Jones,31 with permission of Arthroscopy.)
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