Uemura Keisuke, Takao Masaki, Hamada Hidetoshi, Sakai Takashi, Sugano Nobuhiko
Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Artif Organs. 2018 Mar;42(3):290-296. doi: 10.1111/aor.12998. Epub 2017 Oct 3.
Stem anteversion in the setting of total hip arthroplasty (THA) is usually measured by referencing the posterior condylar line (PCL). However, stem anteversion may not express the functional torsion of the femur if a consistent horizontal tilt in the PCL is observed after THA. Herein, the horizontal tilt of the PCL at the resting neutral position of the hip was retrospectively measured in 53 THA patients from three computed tomography (CT) datasets: (i) preoperative (preop-CT), (ii) 3 weeks after THA (1st postop-CT), and (iii) more than 2 years after THA (2nd postop-CT). Factors including sex, surgical approach, change in femoral anteversion, leg length, leg lateral length, and pelvic sagittal tilt, were analyzed to determine if they were predictors for the rotational change in PCL, and the number of cases in which the horizontal tilt of the PCL remained within 10° in the three CT images was calculated. Comparing the preop-CT to the 1st postop-CT demonstrated that the PCL underwent internal rotation by (mean ± standard deviation) 13.1° ± 8.6°; only leg lateralization was significantly correlated to the change in PCL (β = 0.278, P = 0.046). Comparing the preop-CT to the 2nd postop-CT demonstrated that the PCL was internally rotated by 9.7° ± 9.3°; no factors were correlated to the change in PCL. There were only 12 hips (23%) in which the horizontal tilt of the PCL remained within 10°. In conclusion, the PCL in the resting position was internally rotated shortly after THA and remained internally rotated from the preoperative position at two or more years following THA. Thus, stem anteversion measured by referencing the PCL may not represent functional torsion of the femur.
全髋关节置换术（THA）中，股骨柄前倾角通常通过参考后髁线（PCL）来测量。然而，如果在THA后观察到PCL存在一致的水平倾斜，股骨柄前倾角可能无法体现股骨的功能扭转。在此，我们回顾性测量了来自三个计算机断层扫描（CT）数据集的53例THA患者在髋关节静息中立位时PCL的水平倾斜情况：（i）术前（术前CT），（ii）THA后3周（术后第1次CT），以及（iii）THA后超过2年（术后第2次CT）。分析了包括性别、手术入路、股骨前倾角变化、腿长、腿外侧长度和骨盆矢状面倾斜等因素，以确定它们是否为PCL旋转变化的预测因素，并计算了三个CT图像中PCL水平倾斜保持在10°以内的病例数。术前CT与术后第1次CT比较显示，PCL发生内旋（平均值±标准差）13.1°±8.6°；只有腿外移与PCL的变化显著相关（β = 0.278，P = 0.046）。术前CT与术后第2次CT比较显示，PCL内旋9.7°±9.3°；没有因素与PCL的变化相关。只有12个髋关节（23%）的PCL水平倾斜保持在10°以内。总之，THA后不久，静息位的PCL发生内旋，并且在THA后两年或更长时间内相对于术前位置仍保持内旋。因此，通过参考PCL测量的股骨柄前倾角可能无法代表股骨的功能扭转。
