INTRODUCTION Computer-assisted surgery (CAS) relying on registration of the anterior pelvic plane (APP) allows precise acetabular component placement. We determined the variability of cup placement in patients who underwent THA with and without the use of CAS that does not rely on the registration of APP. METHODS Fifty-one patients who underwent staged-bilateral THAs, one without CAS (control), and a subsequent one with CAS (study group), were included. Acetabular inclination and anteversion were measured on standardized post-operative radiographs. Variance in cup position and Lewinnek's zone proportionality were compared between the groups. Multiple regressions were performed to identify factors affecting variability in acetabular component placement. RESULTS The mean inclination for the control and study group was 42.7° (SD 4.5) and 42.5° (SD 2.9), respectively. The inclination variance was 20.5° and 8.2° respectively (p = < 0.001). Cup inclination was more consistent in the study than in the control group (deviation from the mean: 2.3° vs. 3.8°, p < 0.001). The mean anteversion for the control and the study group was 25.5° (SD 7.4) and 26.8° (SD 4.3), respectively. The anteversion variance was 54.2° and 18.2° respectively (p = <0.001). Consistency in cup anteversion was significantly improved with CAS (deviation from the mean: 3.4° vs. 5.8°; p = 0.002). Lewinnek's zone proportionality was not affected by the use of CAS. In the linear regression analysis, CAS significantly increased consistency in cup inclination (p = 0.01). Patient's factors including BMI and laterality affected consistency of cup placement. CONCLUSION CAS without referencing the APP allows a more consistent orientation of the acetabular component when compared to freehand placement.

中文翻译：

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髋臼定位与新型微型计算机辅助设备的使用更加一致。


简介 计算机辅助手术 (CAS) 依靠骨盆前平面 (APP) 的配准，实现髋臼假体的精确放置。我们确定了接受 THA 的患者在使用和不使用不依赖 APP 注册的 CAS 的情况下杯子放置的变异性。方法 纳入了 51 名接受分期双侧 THA 的患者，其中一名没有 CAS（对照），另一名有 CAS（研究组）。在标准化的术后X光片上测量髋臼倾斜度和前倾角。比较各组之间罩杯位置的差异和 Lewinnek 区域比例。进行多重回归以确定影响髋臼假体放置变异性的因素。结果 对照组和研究组的平均倾斜度分别为 42.7° (SD 4.5) 和 42.5° (SD 2.9)。倾角方差分别为 20.5° 和 8.2° (p = < 0.001)。研究中的罩杯倾斜度比对照组更加一致（平均值偏差：2.3° vs. 3.8°，p < 0.001）。对照组和研究组的平均前倾角分别为 25.5° (SD 7.4) 和 26.8° (SD 4.3)。前倾角方差分别为 54.2° 和 18.2° (p = <0.001)。 CAS 后杯前倾的一致性得到显着改善（平均值偏差：3.4° 与 5.8°；p = 0.002）。 Lewinnek 的区域比例不受 CAS 的使用影响。在线性回归分析中，CAS 显着提高了罩杯倾斜度的一致性 (p = 0.01)。患者的体重指数和偏侧性等因素会影响杯子放置的一致性。结论 与徒手放置相比，不参考 APP 的 CAS 可以使髋臼假体的方向更加一致。