Background

Little is known about the relationship between vertical ground reaction force (vGRF) and muscle strength while climbing stairs after total hip arthroplasty (THA).

Methods

We investigated the relationship between muscle strength and vGRF during stair climbing in 21 women with THA. Differences in the time required to climb stairs and side-to-side differences in muscle strength and vGRF during climbing were examined at 6 and 12 months.

The relationship between climbing time and vGRF variables and that between vGRF and muscle strength were analyzed using Spearman's rank correlation coefficient at 6 and 12 months. First peak force (Fz1) was defined as the peak vGRF at heel strike normalized by body weight.

Findings

Climbing time was related to the time to Fz1 at 6 and 12 months post-THA (r = 0.50–0.64). At 6 months, time to Fz1 was related to the strength of muscles involved in hip extension in the operated limb (r = −0.46). At 12 months, time to Fz1 was related to the strength of muscles responsible for knee extension in the operated limb (r = −0.45).

Interpretation

At 6 months, climbing stairs depended on muscle strength in the hip extensors. Conversely, at 12 months, the functional recovery of knee extensors was important for transferring weight upward while climbing stairs. Therefore, to improve the climbing function of patients with THA, it is important to not only focus on the recovery of muscle strength in the hip extensors but also improve muscle strength in the knee extensors.

中文翻译：

---

全髋关节置换术后爬楼梯时垂直地面反作用力与肌肉力量之间的关系。

背景

对于全髋关节置换术（THA）后爬楼梯时垂直地面反作用力（vGRF）和肌肉力量之间的关系知之甚少。

方法

我们调查了21名THA妇女在爬楼梯过程中肌肉力量与vGRF之间的关系。在第6和12个月时检查了爬楼梯所需时间的差异以及攀爬过程中肌肉力量和vGRF的左右差异。

使用Spearman等级相关系数在6和12个月时分析了攀爬时间与vGRF变量之间的关系以及vGRF与肌肉力量之间的关系。第一个峰值力（ Fz1）定义为通过体重标准化的脚跟撞击时的峰值vGRF。

发现

攀爬时间与THA后6个月和12个月到达Fz1的时间有关（r  = 0.50–0.64）。在6个月时，到达Fz1的时间与手术肢体髋关节伸展所涉及的肌肉强度有关（r  = -0.46）。在12个月时，到达Fz1的时间与负责手术肢体膝盖伸展的肌肉力量有关（r  = -0.45）。

解释

在六个月时，爬楼梯取决于臀部伸肌的肌肉力量。相反，在12个月时，膝上伸肌的功能恢复对于在爬楼梯时向上转移体重很重要。因此，为了改善THA患者的攀爬功能，重要的是不仅要着眼于髋伸肌的肌肉力量的恢复，而且要改善膝盖伸肌的肌肉力量。