The role of the iliopsoas as an obstructing and re-dislocating factor in developmentally dislocated hips is unclear. The purpose of this article is to determine the change in the iliopsoas’ tension during flexion and extension when performing an open reduction. We evaluated 34 hips undergoing an anterior open reduction for a developmental dislocation. At the time of surgery, we identified the iliopsoas, and before sectioning it as part of the open reduction, we measured the tension while cycling the reduced hip through flexion and extension. We performed statistical analysis using Pearson and Spearman correlation tests. We created an initial tension artificially at 20 N with the hip held in 90º of flexion, which then doubled to a mean of 42 N when placed in extension. We found a significant increase in tension when the hip went below 20º of flexion. We also found the correlation between the angle of the hip and the force of tension to be statistically significant (P = 0.003). This study provides quantitative support that the tension of the iliopsoas tendon increases significantly in extension when performing an open reduction of a developmentally dislocated hip.

髂腰肌作为发育性髋关节脱位的阻碍和再脱位因素的作用尚不清楚。本文的目的是确定进行切开复位时屈曲和伸展过程中髂腰肌张力的变化。我们评估了 34 个因发育性脱位而接受前路切开复位术的髋关节。在手术时，我们识别了髂腰肌，在将其切开作为切开复位的一部分之前，我们测量了通过屈曲和伸展循环复位的髋部时的张力。我们使用 Pearson 和 Spearman 相关性检验进行统计分析。我们在髋关节屈曲 90° 的情况下人为地产生 20 N 的初始张力，然后在伸展时加倍至平均 42 N。我们发现当髋部屈曲低于 20° 时，张力显着增加。我们还发现髋部角度与张力之间的相关性具有统计学意义（P  = 0.003）。这项研究提供了定量支持，即当对发育性脱位髋关节进行切开复位时，髂腰肌腱的张力在伸展过程中显着增加。