全髋关节置换术后聚乙烯内衬磨损的测量及其临床意义

Measurement of polyethylene wear and its clinical significance in total hip arthroplasty

目的以计算机数字化方法计测人工全髋假体二维线性磨损，并探讨磨损程度与长期随访结果的临床相关性。方法利用计算机软件测量股骨头中心相对于髋臼中心的矢量位移，来决定关节面磨损的大小和方向。对 104髋非骨水泥型人工假体进行磨损计测、临床和放射学检查，平均随访时间为 8.4年。结果 14髋股骨或髋臼假体松动，假体松动率为 13.5％。平均线性磨损值为 1.14 mm，磨损率为 0.15 mm/年。聚乙烯磨损与髋臼侧骨溶解及假体松动相关 (P< 0.05)。多因素回归分析未发现磨损和患者年龄、体重、髋杯大小和外展角、活动量水平以及 Harris髋关节评分的相关关系。结论此方法可应用于各种不同设计的人工假体内衬的二维磨损测量。磨损与骨溶解显著相关，并与假体松动互为因果。因此，在进行临床随访、放射学观察的同时，磨损情况也是全面评价全髋置换术临床结果的一个重要指标。

Objective To measure the linear polyethylene wear with use of a computer-assisted two-dimensional method, and to evaluate the relationship between wear and long-term clinic-radiological findings. Methods Radiographs of 104 cementless total hip arthroplasties were examined for osteolysis, radiolucent line, cup abduction angle, cup migration, cancellous condensation, stem subsidence, distal pedestal formation and so on. To measure the linear polyethylene wear, migration in the femoral head center relative to the cup shell center was calculated on digitized consecutive radiographs with special computer software program, the degree and direction of wear were also determined. Patients were followed-up for an average period of 8.4 years. Results The average Harris Hip Score was 53.8 points preoperatively and 88.5 points at the latest follow-up. Fourteen hips (13.5％ ) were loose. Total linear wear was 1.14 mm， wear rate was 0.15 mm/year. Acetabular osteolysis was correlated to polyethylene wear, and a high wear rate was associated with loosening of the components. Multivariate regression analysis showed a lack of correlation between wear rate and patients age, body weight, cup size, cup abduction angle, activity level and Harris Hip Score. Conclusion The method is preferable for measuring the polyethylene wear of metal-backed acetabular component and other components of various designs. There was clear relationship between wear and acetabular osteolysis or loosening of the prostheses. Therefore, polyethylene wear is important in evaluating the clinical and radiological outcomes of total hip arthroplasty.