Effect of Postoperative Mechanical Axis Alignment on the Fifteen-Year Survival of Modern, Cemented Total Knee Replacements
Effect of Postoperative Mechanical Axis Alignment on the Fifteen-Year Survival of Modern, Cemented Total Knee Replacements
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DOI：
10.2106/jbjs.i.01398
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发表时间：
2010-09-15
影响因子：
5.3
通讯作者：
Berry, Daniel J.
中科院分区：
文献类型：
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作者：
Parratte, Sebastien;Pagnano, Mark W.;Berry, Daniel J.
背景：全膝关节置换术的一项长期坚持的原则是，当术后肢体对齐相对于机械轴校正为 0 度 +/- 3 度时，植入物的耐用性最大化。最近，大量的医疗保健资源投入到计算机导航系统上，使外科医生能够更频繁地实现这种对准。我们假设，与一组离群值相比，术后机械轴 0 度 +/- 3 度将导致全膝关节置换术植入物的长期生存率更高。方法：回顾性审查临床和放射学数据，以确定对 280 名患者进行了 398 例初次全膝关节置换术后的 15 年 Kaplan-Meier 生存率 1985 年至 1990 年。术前，大多数膝关节处于内翻机械对准状态（平均和标准偏差，内翻 6 度 +/- 8.8 度 [范围，内翻 30 度到外翻 22 度]），而术后大多数膝关节被矫正至中性（平均和标准偏差，0 度 +/- 2.8 度 [范围，内翻 8 度到外翻 9 度]） 外翻]）。术后，我们定义了一个由 292 个膝关节组成的机械对齐组（机械轴为 0 度 +/- 3 度）和一个由 106 个膝关节组成的离群组（机械轴超出 0 度 +/- 3 度）。 结果：在最近一次随访时，机械对齐组中的 292 个植入物中，有 45 个 (15.4%) 已针对任何需要进行了修改。 原因，与异常组中 106 个种植体中的 14 个 (13%) 相比 (p = 0.88)；机械对齐组的 292 个种植体中，有 27 个 (9.2%) 由于无菌性松动、机械故障、磨损或髌骨问题而进行了修整，而异常组的 106 个种植体中有 8 个 (7.5%) (p = 0.88)；机械对齐组的 292 个种植体中，有 17 个 (5.8%) 由于无菌性松动、机械故障或磨损而进行了修整，而异常组的 106 个种植体中有 4 个 (3.8%) (p = 0.49)。 结论：术后机械轴 0 度 +/- 3 度并没有提高这 398 个现代种植体的 15 年种植体存活率 全膝关节置换术。我们认为，基于 0 度 +/- 3 度的机械轴目标将对齐描述为二分变量（对齐与未对齐）对于预测现代全膝关节置换术植入物的耐用性几乎没有实际价值。
Background: One long-held tenet of total knee arthroplasty is that implant durability is maximized when postoperative limb alignment is corrected to 0 degrees +/- 3 degrees relative to the mechanical axis. Recently, substantial health-care resources have been devoted to computer navigation systems that allow surgeons to more often achieve that alignment. We hypothesized that a postoperative mechanical axis of 0 degrees +/- 3 degrees would result in better long-term survival of total knee arthroplasty implants as compared with that in a group of outliers.Methods: Clinical and radiographic data were reviewed retrospectively to determine the fifteen-year Kaplan-Meier survival rate following 398 primary total knee arthroplasties performed with cement in 280 patients from 1985 to 1990. Preoperatively, most knees were in varus mechanical alignment (mean and standard deviation, 6 degrees +/- 8.8 degrees of varus [range, 30 degrees of varus to 22 degrees of valgus]), whereas postoperatively most knees were corrected to neutral (mean and standard deviation, 0 degrees +/- 2.8 degrees [range, 8 degrees of varus to 9 degrees of valgus]). Postoperatively, we defined a mechanically aligned group of 292 knees (with a mechanical axis of 0 degrees +/- 3 degrees) and an outlier group of 106 knees (with a mechanical axis of beyond 0 degrees +/- 3 degrees).Results: At the time of the latest follow-up, forty-five (15.4%) of the 292 implants in the mechanically aligned group had been revised for any reason, compared with fourteen (13%) of the 106 implants in the outlier group (p = 0.88); twentyseven (9.2%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, wear, or patellar problems, compared with eight (7.5%) of the 106 implants in the outlier group (p = 0.88); and seventeen (5.8%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, or wear, compared with four (3.8%) of the 106 implants in the outlier group (p = 0.49).Conclusions: A postoperative mechanical axis of 0 degrees +/- 3 degrees did not improve the fifteen-year implant survival rate following these 398 modern total knee arthroplasties. We believe that describing alignment as a dichotomous variable (aligned versus malaligned) on the basis of a mechanical axis goal of 0 degrees +/- 3 degrees is of little practical value for predicting the durability of modern total knee arthroplasty implants.