St Louis Joint Replacement Institute, SSM DePaul Health Center, 12266 DePaul Drive, Suite 220, St Louis, MO, 63044, USA,
Clin Orthop Relat Res. 2013 Nov;471(11):3533-9. doi: 10.1007/s11999-013-3174-5. Epub 2013 Aug 2.
The Oxford knee is a unicompartmental implant featuring a mobile-bearing polyethylene component with excellent long-term survivorship results reported by the implant developers and early adopters. By contrast, other studies have reported higher revision rates in large academic practices and in national registries. Registry data have shown increased failure with this implant especially by lower-volume surgeons and institutions.
QUESTIONS/PURPOSES: In the setting of a high-volume knee arthroplasty practice, we sought to determine (1) the failure rate of the Oxford unicompartmental knee implant using a failure definition for aseptic loosening that combined clinical features, plain radiographs, and scintigraphy, and (2) whether increased experience with this implant would decrease failure rate, if there is a learning curve effect.
Eighty-three Oxford knee prostheses were implanted between September 2005 and July 2008 by the principal investigator. Radiographic and clinical data were available for review for all cases. A failed knee was defined as having recurrent pain after an earlier period of recovery from surgery, progressive radiolucent lines compared with initial postoperative radiographs, and a bone scan showing an isolated area of uptake limited to the area of the replaced compartment.
Eleven knees in this series failed (13%); Kaplan-Meier survivorship was 86.5% (95% CI, 78.0%-95.0%) at 5 years. Failure occurrences were distributed evenly over the course of the study period. No learning curve effect was identified.
Based on these findings, including a high failure rate of the Oxford knee implant and the absence of any discernible learning curve effect, the principal investigator no longer uses this implant.
牛津膝关节是一种单髁关节置换假体，具有活动衬垫聚乙烯组件，植入物开发者和早期使用者报告了其优异的长期存活率。相比之下，其他研究报告在大型学术实践和国家登记处的翻修率更高。登记数据显示，该植入物的失败率增加，尤其是在低容量外科医生和机构中。
问题/目的：在高容量膝关节置换手术实践中，我们试图确定（1）使用结合临床特征、普通 X 线片和闪烁扫描的无菌性松动失效定义，牛津单髁膝关节置换假体的失败率，以及（2）如果存在学习曲线效应，是否增加对该植入物的经验会降低失败率。
主要研究者在 2005 年 9 月至 2008 年 7 月期间植入了 83 例牛津膝关节假体。所有病例均有影像学和临床数据可供回顾。失败的膝关节被定义为手术后恢复早期出现反复疼痛、与术后初始 X 线片相比出现进行性透亮线，以及骨扫描显示孤立的摄取区域仅限于置换间隙的区域。
本系列中有 11 例膝关节失败（13%）；Kaplan-Meier 生存率为 5 年时 86.5%（95%CI，78.0%-95.0%）。失败发生均匀分布在研究期间。未发现学习曲线效应。
基于这些发现，包括牛津膝关节植入物的高失败率和缺乏任何明显的学习曲线效应，主要研究者不再使用该植入物。
