Department of Orthopaedic Surgery, Iizuka Hospital, 3-83 Yoshiomachi, Iizuka 820-8505, Japan.
Department of Orthopaedic Surgery, Fukuoka Mirai Hospital, 3-5-1 Higashi-Ku, Fukuoka 813-0017, Japan.
J Orthop Sci. 2024 Sep;29(5):1235-1241. doi: 10.1016/j.jos.2023.08.008. Epub 2023 Aug 16.
Intraoperative stem anteversion, which is the angle between the lower leg axis and the trial-stem axis with hip flexion and adduction, is generally evaluated by the surgeon's visual estimation during total hip arthroplasty (THA). However, the conventional approach can be influenced by knee osteoarthritis or uncertain surgeon's observation point. Therefore, we developed a new method for measuring the stem anteversion angle in the neutral hip position using an original rod attached to the trial-stem perpendicular to the long axis and parallel to the stem neck. This study aimed to assess the accuracy of our method in comparison with the conventional method of measuring intraoperative stem anteversion angle.
We measured the intraoperative stem anteversion angle in consecutive 106 hips of 106 patients who underwent cementless primary THA with a tapered wedge stem. Absolute error in the stem anteversion angle was expressed as the difference between intraoperative (common vs. neutral hip positions) and postoperative computed tomography measurements, i.e., true stem anteversion. Additionally, we investigated the factors affecting these errors.
The absolute error of measurement was significantly smaller in the neutral hip position than in the common position (3.0° ± 2.5° vs. 8.0° ± 3.9°; p < 0.0001). The factor associated with the error was advanced knee osteoarthritis in the common position, whereas it was not statistically significant in the neutral hip position.
This study suggests that the error in the intraoperative measurement of stem anteversion is decreased by measuring in the neutral hip position during THA.
术中股骨前倾角是指髋关节屈曲和内收时，小腿轴与试模轴之间的夹角，通常由外科医生在全髋关节置换术（THA）过程中通过目测来评估。然而，传统方法可能会受到膝关节骨关节炎或不确定的外科医生观察点的影响。因此，我们开发了一种新的方法，即在中立位髋关节使用与试模垂直且与股骨颈平行的原始杆来测量股骨前倾角。本研究旨在评估与术中股骨前倾角常规测量方法相比，我们的方法的准确性。
我们测量了 106 例接受非骨水泥锥形楔形股骨柄初次 THA 的患者连续 106 髋术中股骨前倾角。术中（通用 vs. 中立髋关节位置）和术后 CT 测量的股骨前倾角的绝对误差表示为真实股骨前倾角的差异。此外，我们还研究了影响这些误差的因素。
中立髋关节位置的测量误差明显小于通用位置（3.0°±2.5° vs. 8.0°±3.9°；p<0.0001）。在通用位置，与误差相关的因素是膝关节骨关节炎进展，而在中立髋关节位置，该因素无统计学意义。
本研究表明，在 THA 过程中测量中立髋关节位置可以降低术中股骨前倾角测量的误差。
