Steinberg M E, Corces A, Fallon M
Department of Orthopaedic Surgery, Hospital of the University of Pennsylvania, Philadelphia 19104, USA.
J Bone Joint Surg Am. 1999 Jan;81(1):60-5.
When an arthroplasty is needed to treat osteonecrosis of the femoral head, the use of a component that replaces or resurfaces only the femoral head is often considered as an alternative to total hip replacement if the acetabulum appears radiographically normal. However, the long-term results of the use of endoprostheses have often been poor, secondary in part to progressive degeneration of the acetabular cartilage and to protrusio acetabuli. To help to explain these observations, we examined the acetabular cartilage in forty-one hips in which a primary total hip replacement had been performed because of osteonecrosis of the femoral head in association with a radiographically normal acetabulum. The cartilage in the superior, weight-bearing region of the acetabulum was grossly abnormal in forty of the forty-one hips and it was histologically abnormal in all thirty-three hips that were so evaluated. In all but one hip, gross degeneration of the cartilage was apparent, involving less than 20 percent of the acetabulum; the degeneration was graded as mild (superficial fibrillation and slight irregularity of the surface) in sixteen hips, moderate (moderate fibrillation, alteration in color and consistency, and thinning of cartilage without complete erosion to bone) in twenty hips, and severe (marked fibrillation, alteration in color and consistency, and marked thinning of cartilage with areas of complete erosion to bone) in four hips. These observations emphasize the fact that radiographs cannot demonstrate early degeneration of cartilage and that, by the time that an arthroplasty is needed, degenerative changes are already present in the acetabular cartilage of a high percentage of hips with osteonecrosis, even when radiographs of the acetabulum show no abnormalities. These findings should be kept in mind when a decision is being made regarding which type of arthroplasty should be done in a patient who has osteonecrosis of the femoral head and regarding when to do the procedure.
当需要进行关节置换术来治疗股骨头坏死时，如果髋臼在X线片上显示正常，那么使用仅置换或修复股骨头的假体组件通常被视为全髋关节置换的一种替代方案。然而，使用人工关节假体的长期效果往往不佳，部分原因是髋臼软骨的渐进性退变以及髋臼内陷。为了帮助解释这些观察结果，我们检查了41例因股骨头坏死且髋臼X线片正常而接受初次全髋关节置换术的患者的髋臼软骨。在这41例患者中，有40例髋臼上半部分负重区域的软骨肉眼观察明显异常，在接受组织学评估的33例患者中，所有患者的软骨均有组织学异常。除1例患者外，其余所有患者的软骨均有明显的退变，累及髋臼不到20%；其中16例患者的退变程度为轻度（表面轻度纤维化和轻微不规则），20例为中度（中度纤维化、颜色和质地改变以及软骨变薄但未完全侵蚀至骨质），4例为重度（明显纤维化、颜色和质地改变以及软骨明显变薄且有部分区域完全侵蚀至骨质）。这些观察结果强调了一个事实，即X线片无法显示软骨的早期退变，而且在需要进行关节置换术时，即使髋臼X线片显示无异常，高比例的股骨头坏死患者的髋臼软骨已经出现了退变改变。在决定对股骨头坏死患者应进行何种类型的关节置换术以及何时进行手术时，应牢记这些发现。
