Institute of Cellular Medicine, University of Newcastle upon Tyne, Newcastle, NE1 7RU, England.
J Bone Joint Surg Am. 2012 Sep 5;94(17):e126. doi: 10.2106/JBJS.K.00791.
Unicompartmental knee arthroplasty has been associated with consistently worse implant survival rates than total knee arthroplasty in worldwide arthroplasty registers. The rate of revision and the proportion of revisions performed for unexplained knee pain after either a unicompartmental or total knee arthroplasty were studied to assess if there is evidence to support the hypothesis that the numbers of revisions performed for unexplained knee pain differ between these two implant types.
Using data from the National Joint Registry (NJR) of England and Wales, we identified 402,714 primary knee arthroplasties (366,965 total knee arthroplasties and 35,749 unicompartmental knee arthroplasties) that were consecutively entered from April 2003 to December 2010. The status of all implants was assessed as of December 2010, at which time 6075 implants (4503 total knee implants and 1572 unicompartmental knee implants) had been revised at a maximum of eight years. Survival analysis and Cox regression analysis with adjustment of differences in age, sex, American Society of Anesthesiologists (ASA) grade, and indication for arthroplasty were performed with use of the end points of revision for any reason, revision for unexplained pain, and revision for other reasons.
Revision for unexplained pain was more common after unicompartmental knee arthroplasty than after total knee arthroplasty (representing 23% of revisions as compared with 9% of revisions; p < 0.001). The five-year rate of revision for unexplained pain was 1.6% for the unicompartmental knee arthroplasty group and 0.2% for the total knee arthroplasty group. With use of Cox regression, the hazard ratio (HR) for unicompartmental knee arthroplasty relative to total knee arthroplasty with the end points of revision for any reason, revision for unexplained pain, and revision for all other reasons were 2.82 (95% confidence interval [CI], 2.66 to 2.99; p < 0.001), 6.76 (95% CI, 5.84 to 7.83; p < 0.001), and 2.39 (95% CI, 2.24 to 2.56; p < 0.001), respectively. The mean time from primary implantation to revision was similar for both implant types.
While more unicompartmental knee implants than total knee implants were revised for unexplained pain, when these revisions for unexplained pain were discounted, unicompartmental knee arthroplasty still had a significantly greater risk of revision from other reasons than did total knee arthroplasty. The revision rate in isolation may not be a reliable way to compare different implant designs and should instead be considered in the context of the reason for failure.
在全球关节置换登记处，单髁膝关节置换术的假体生存率一直明显低于全膝关节置换术。本研究旨在评估单髁膝关节置换术和全膝关节置换术后不明原因膝关节疼痛的翻修率和翻修原因，以验证是否有证据支持这样的假设，即两种假体类型的不明原因膝关节疼痛翻修数量存在差异。
我们利用英格兰和威尔士国家关节登记处（NJR）的数据，对 2003 年 4 月至 2010 年 12 月连续登记的 402714 例初次膝关节置换术（366965 例全膝关节置换术和 35749 例单髁膝关节置换术）进行了评估。截至 2010 年 12 月，所有假体的状态都进行了评估，此时共有 6075 例假体（4503 例全膝关节置换术和 1572 例单髁膝关节置换术）接受了最多 8 年的翻修。我们进行了生存分析和 Cox 回归分析，调整了年龄、性别、美国麻醉医师协会（ASA）分级和关节置换适应证的差异，以任何原因的翻修、不明原因疼痛的翻修和其他原因的翻修为终点。
与全膝关节置换术相比，单髁膝关节置换术后不明原因疼痛的翻修更为常见（分别占翻修的 23%和 9%；P<0.001）。单髁膝关节置换术组和全膝关节置换术组不明原因疼痛的 5 年翻修率分别为 1.6%和 0.2%。使用 Cox 回归，单髁膝关节置换术相对于全膝关节置换术的任何原因翻修、不明原因疼痛翻修和其他所有原因翻修的风险比（HR）分别为 2.82（95%可信区间[CI]，2.66 至 2.99；P<0.001）、6.76（95% CI，5.84 至 7.83；P<0.001）和 2.39（95% CI，2.24 至 2.56；P<0.001）。两种假体类型的初次植入后平均翻修时间相似。
虽然不明原因疼痛导致更多的单髁膝关节置换术需要翻修，但如果排除这些不明原因疼痛的翻修，单髁膝关节置换术的其他原因翻修风险仍明显高于全膝关节置换术。单纯的翻修率可能不是比较不同假体设计的可靠方法，而应结合失败原因进行考虑。
