Price A J, Short A, Kellett C, Beard D, Gill H, Pandit H, Dodd C A F, Murray D W
Nuffield Orthopaedic Centre, Windmill Road, Headington, Oxford OX3 7LD, UK.
J Bone Joint Surg Br. 2005 Nov;87(11):1493-7. doi: 10.1302/0301-620X.87B11.16325.
Polyethylene particulate wear debris continues to be implicated in the aetiology of aseptic loosening following knee arthroplasty. The Oxford unicompartmental knee arthroplasty employs a spherical femoral component and a fully congruous meniscal bearing to increase contact area and theoretically reduce the potential for polyethylene wear. This study measures the in vivo ten-year linear wear of the device, using a roentgenstereophotogrammetric technique. In this in vivo study, seven medial Oxford unicompartmental prostheses, which had been implanted ten years previously were studied. Stereo pairs of radiographs were acquired for each patient and the films were analysed using a roentgen stereophotogrammetric analysis calibration and a computer-aided design model silhouette-fitting technique. Penetration of the femoral component into the original volume of the bearing was our estimate of linear wear. In addition, eight control patients were examined less than three weeks post-insertion of an Oxford prosthesis, where no wear would be expected. The control group showed no measured wear and suggested a system accuracy of 0.1 mm. At ten years, the mean linear wear rate was 0.02 mm/year. The results from this in vivo study confirm that the device has low ten-year linear wear in clinical practice. This may offer the device a survival advantage in the long term.
聚乙烯颗粒磨损碎片仍然被认为与膝关节置换术后无菌性松动的病因有关。牛津单髁膝关节置换术采用球形股骨部件和完全贴合的半月板假体，以增加接触面积，并在理论上降低聚乙烯磨损的可能性。本研究采用X线立体摄影测量技术，对该装置在体内的十年线性磨损情况进行测量。在这项体内研究中，对7例十年前植入的内侧牛津单髁假体进行了研究。为每位患者采集立体X线片，并使用X线立体摄影测量分析校准和计算机辅助设计模型轮廓拟合技术对胶片进行分析。股骨部件向原始假体容积内的穿透情况是我们对线性磨损的评估指标。此外，对8例牛津假体植入后不到三周的对照患者进行了检查，预计此时不会出现磨损。对照组未检测到磨损，表明系统精度为0.1毫米。十年时，平均线性磨损率为每年0.02毫米。这项体内研究结果证实，在临床实践中，该装置十年线性磨损率较低。从长远来看，这可能会使该装置具有生存优势。
