Bennett D, Orr J F, Beverland D E, Baker R
Musgrave Park Hospital, Belfast, Northern Ireland, UK.
Proc Inst Mech Eng H. 2002;216(6):393-402. doi: 10.1243/095441102321032184.
Wear of the polyethylene acetabular component is the most serious threat to the long-term success of total hip replacements (THRs). Greatly reduced wear rates have been reported for unidirectional, compared to multidirectional, articulation in vitro. This study considers the multidirectional motions experienced at the hip joint as described by movement loci of points on the femoral head for individual THR patients. A three-dimensional computer program determined the movement loci of selected points on the femoral head for THR patients and normal subjects using kinematic data obtained from gait analysis. The sizes and shapes of these loci were quantified by their sliding distances and aspect ratios with substantial differences exhibited between individual THR patients. The average sliding distances ranged from 10.0 to 18.1 mm and the average aspect ratios of the loci ranged from 2.5 to 9.2 for the THR patients. Positive correlations were found between wear rate and average sliding distance, the inverse of the average aspect ratio of the loci and the product of the average sliding distance and the inverse of the average aspect ratio of the loci. Patients with a normal hip joint range of motion produce multidirectional motion loci and tend to experience more wear than patients with more unidirectional motion loci. Differing patterns of multidirectional motion at the hip joint for individual THR patients may explain widely differing wear rates in vivo.
聚乙烯髋臼部件的磨损是全髋关节置换术（THR）长期成功的最严重威胁。据报道，与多向运动相比，单向运动在体外的磨损率大大降低。本研究考虑了个体THR患者股骨头各点运动轨迹所描述的髋关节多向运动。一个三维计算机程序使用从步态分析获得的运动学数据，确定了THR患者和正常受试者股骨头选定各点的运动轨迹。这些轨迹的大小和形状通过其滑动距离和纵横比进行量化，个体THR患者之间表现出显著差异。THR患者的平均滑动距离在10.0至18.1毫米之间，轨迹的平均纵横比在2.5至9.2之间。磨损率与平均滑动距离、轨迹平均纵横比的倒数以及平均滑动距离与轨迹平均纵横比的倒数的乘积之间存在正相关。髋关节活动范围正常的患者产生多向运动轨迹，并且往往比具有更多单向运动轨迹的患者经历更多磨损。个体THR患者髋关节多向运动的不同模式可能解释了体内磨损率的广泛差异。
