Watanabe H, Shimada Y, Sato K, Tsutsumi Y, Sato M
Department of Orthopedic Surgery, Akita University School of Medicine, Japan.
Biomed Mater Eng. 1998;8(3-4):177-86.
Intertrochanteric varus osteotomy of the femur for hip osteoarthritis is expected to bring improved congruity and increased weight-bearing surface area of the hip joint. Before surgery, we usually make a tracing on a paper using an anteroposterior roentgenogram of the hip to simulate the operating procedures and obtain better conditions in the hip. Nevertheless, there have been some cases in which this procedure does not provide satisfactory postoperative results in terms of relief of pain or locomotion, with long-term limp due to weakness of the hip abductor muscle group and shortening of the leg.
To confirm if the improved congruity and increased covering of the weight-bearing surface area obtained by varus osteotomy can be actually reproduced during walking, and to evaluate the kinetic mechanism of the effects of this procedure using gait analysis.
We measured the strength ratio of the hip abductor muscles as the percent of the opposite side, and analyzed the pelvic movement and data of dynamic electromyography (EMG) recorded during locomotion in 24 female patients who underwent unilateral intertrochanteric varus osteotomy of the femur for hip osteoarthritis, 30 non-surgically-treated female patients with hip osteoarthritis, and 54 healthy women. In the operated patients, the roentgenograms obtained during one-legged stance on the affected side disclosed that 10 were positive for Trendelenburg's phenomenon (T(+) group) and 14 were negative for Trendelenburg's phenomenon (T(-) group). All subjects walked with bare feet at a comfortable pace on a walkway containing a force plate. Photo switches were placed in a walkway to measure the gait velocity and to determine the stance phase time of one gait cycle. Frontal and sagittal trajectories of body surface markers for computerized joint-angle motion analysis were acquired using the Quick-MAG system. EMG data for the gluteus maximus, gluteus medius, tensor fascia latae, and lateral hamstrings recorded using surface electrodes were integrated to quantify as the percent of maximum voluntary contraction (% MVC).
This study disclosed that the stance phase time was shorter and the strength ratio of the hip abductor muscles was lower in the operated patients than those in the other 2 groups, and the change of the pelvic obliquity was smaller and the % MVC of the gluteus medius and tensor fascia latae were greater than those in the normal subjects. The change of the pelvic tilt showed the same pattern with those of the pelvic obliquity. The T(+) group showed decreased strength ratio of the hip abductor muscles and increased % MVC for the gluteus medius and the tensor fascia latae compared to the T(-) group, but the changes of both the pelvic obliquity and pelvic tilt did not significantly differ in the 2 groups.
This study showed the postoperative reappearance of the simulated conditions in the hip before varus osteotomy of the femur, providing evidence that the pelvis was horizontally maintained during walking due to decreased stance phase time and increased performance of the hip abductor muscles after this procedure.
股骨转子间内翻截骨术治疗髋骨关节炎有望改善髋关节的匹配度并增加其负重表面积。手术前，我们通常会利用髋关节前后位X线片在纸上进行描摹，以模拟手术过程并使髋关节处于更好的状态。然而，在某些病例中，该手术在缓解疼痛或改善运动方面并未取得令人满意的术后效果，出现了因髋外展肌群无力和腿部缩短导致的长期跛行。
确认股骨内翻截骨术所获得的改善的匹配度和增加的负重表面积覆盖能否在行走过程中实际重现，并利用步态分析评估该手术效果的动力学机制。
我们测量了髋外展肌力量与对侧相比的百分比，分析了24例因髋骨关节炎接受单侧股骨转子间内翻截骨术的女性患者、30例非手术治疗的髋骨关节炎女性患者以及54例健康女性在行走过程中的骨盆运动和动态肌电图（EMG）数据。在接受手术的患者中，患侧单腿站立时获得的X线片显示，10例为Trendelenburg现象阳性（T(+)组），14例为Trendelenburg现象阴性（T(-)组）。所有受试者赤脚在装有测力板的通道上以舒适的步伐行走。在通道中放置光电开关以测量步态速度并确定一个步态周期的站立相时间。使用Quick-MAG系统获取用于计算机化关节角度运动分析的体表标记物的额状面和矢状面轨迹。使用表面电极记录的臀大肌、臀中肌、阔筋膜张肌和股二头肌外侧头的EMG数据进行积分，以量化为最大自主收缩百分比（%MVC）。
本研究表明，与其他两组相比，接受手术的患者站立相时间较短，髋外展肌力量比更低，骨盆倾斜度变化较小，臀中肌和阔筋膜张肌的%MVC大于正常受试者。骨盆倾斜度的变化与骨盆倾斜的变化模式相同。与T(-)组相比，T(+)组髋外展肌力量比降低，臀中肌和阔筋膜张肌的%MVC增加，但两组骨盆倾斜度和骨盆倾斜度的变化均无显著差异。
本研究显示了股骨内翻截骨术前髋关节模拟状态在术后重现，提供了证据表明该手术后由于站立相时间缩短和髋外展肌性能增加，行走过程中骨盆得以水平维持。
