Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, USA; Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA.
Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA; Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, USA; Department of Orthopaedics and Rehabilitation, The Pennsylvania State University, Hershey, PA, USA.
J Biomech. 2018 Aug 22;77:201-205. doi: 10.1016/j.jbiomech.2018.06.020. Epub 2018 Jun 27.
Geometric and tendon excursion methods have both been used extensively for estimating plantarflexor muscle moment arm in vivo. Geometric measures often utilize magnetic resonance imaging, which can be costly and impractical for many investigations. Estimating moment arm from tendon excursion measured with ultrasonography may provide a cost-effective alternative to geometric measures of moment arm, but how well such measures represent geometry-based moment arms remains in question. The purpose of this study was to determine whether moment arms from tendon excursion can serve as a surrogate for moment arms measured geometrically. Magnetic resonance and ultrasound imaging were performed on 19 young male subjects to quantify plantarflexor moment arm based on geometric and tendon excursion paradigms, respectively. These measurements were weakly correlated that approached statistical significance (R = 0.21, p = 0.052), and moment arm from tendon excursion under-approximated geometric moment arm by nearly 40% (p < 0.001). This weak correlation between methods is at odds with a prior report (N = 9) of a strong correlation (R = 0.94) in a similar study. Therefore, we performed 92,378 regression analyses (19 choose 9) to determine if such a strong correlation existed in our study population. We found that certain sub-populations of the current study generated similarly strong coefficients of determination (R = 0.92), but 84% of all analyses revealed no correlation (p > 0.05). Our results suggest that the moment arms from musculoskeletal geometry cannot be otherwise obtained by simply scaling moment arms estimated from tendon excursion.
几何和肌腱拉伸方法都被广泛用于估计体内跖屈肌力臂。几何测量方法通常使用磁共振成像，这对于许多研究来说可能是昂贵且不切实际的。使用超声测量肌腱拉伸来估计力臂可能是一种经济有效的替代几何力臂测量方法，但这种方法在多大程度上代表基于几何的力臂仍然存在疑问。本研究的目的是确定肌腱拉伸的力臂是否可以作为基于几何的力臂的替代。对 19 名年轻男性进行磁共振和超声成像，分别基于几何和肌腱拉伸范式来量化跖屈肌力臂。这些测量结果之间的相关性较弱，但接近统计学意义（R=0.21，p=0.052），并且肌腱拉伸的力臂比几何力臂低估了近 40%（p<0.001）。这种方法之间的弱相关性与先前一项类似研究（N=9）中强相关性（R=0.94）的报告不一致。因此，我们进行了 92,378 次回归分析（19 选 9），以确定在我们的研究人群中是否存在这种强相关性。我们发现，当前研究的某些亚组产生了类似的强决定系数（R=0.92），但 84%的分析都没有相关性（p>0.05）。我们的研究结果表明，通过简单地对肌腱拉伸估计的力臂进行缩放，无法获得肌肉骨骼几何力臂。
