Kendrick B J L, Longino D, Pandit H, Svard U, Gill H S, Dodd C A F, Murray D W, Price A J
Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD, UK.
J Bone Joint Surg Br. 2010 Mar;92(3):367-73. doi: 10.1302/0301-620X.92B3.22491.
The Oxford Unicompartmental Knee replacement (UKR) was introduced as a design to reduce polyethylene wear. There has been one previous retrieval study involving this implant, which reported very low rates of wear in some specimens but abnormal patterns of wear in others. There has been no further investigation of these abnormal patterns. The bearings were retrieved from 47 patients who had received a medial Oxford UKR for anteromedial osteoarthritis of the knee. None had been studied previously. The mean time to revision was 8.4 years (sd 4.1), with 20 having been implanted for over ten years. The macroscopic pattern of polyethylene wear and the linear penetration were recorded for each bearing. The mean rate of linear penetration was 0.07 mm/year. The patterns of wear fell into three categories, each with a different rate of linear penetration; 1) no abnormal macroscopic wear and a normal articular surface, n = 16 (linear penetration rate = 0.01 mm/year); 2) abnormal macroscopic wear and normal articular surfaces with extra-articular impingement, n = 16 (linear penetration rate = 0.05 mm/year); 3) abnormal macroscopic wear and abnormal articular surfaces with intra-articular impingement +/- signs of non-congruous articulation, n = 15 (linear penetration rate = 0.12 mm/year). The differences in linear penetration rate were statistically significant (p < 0.001). These results show that very low rates of polyethylene wear are possible if the device functions normally. However, if the bearing displays suboptimal function (extra-articular, intra-articular impingement or incongruous articulation) the rates of wear increase significantly.
牛津单髁膝关节置换术（UKR）作为一种旨在减少聚乙烯磨损的设计被引入。此前有一项涉及该植入物的取出研究，报告称一些标本的磨损率非常低，但另一些标本的磨损模式异常。尚未对这些异常模式进行进一步研究。从47例因膝关节前内侧骨关节炎接受内侧牛津UKR的患者中取出了轴承。此前均未进行过研究。翻修的平均时间为8.4年（标准差4.1），其中20例植入时间超过十年。记录每个轴承的聚乙烯磨损宏观模式和线性穿透情况。线性穿透的平均速率为0.07毫米/年。磨损模式分为三类，每类的线性穿透速率不同；1）无异常宏观磨损且关节表面正常，n = 16（线性穿透速率 = 0.01毫米/年）；2）异常宏观磨损且关节表面正常伴有关节外撞击，n = 16（线性穿透速率 = 0.05毫米/年）；3）异常宏观磨损且关节表面异常伴有关节内撞击 +/- 关节不匹配迹象，n = 15（线性穿透速率 = 0.12毫米/年）。线性穿透速率的差异具有统计学意义（p < 0.001）。这些结果表明，如果该装置功能正常，聚乙烯磨损率可能非常低。然而，如果轴承显示功能欠佳（关节外、关节内撞击或关节不匹配），磨损率会显著增加。
