Centre for Sports Medicine and Human Performance, School of Sport and Education, Brunel University, Uxbridge, Middlesex UB8 3PH, UK.
J Appl Physiol (1985). 2010 Dec;109(6):1644-52. doi: 10.1152/japplphysiol.00656.2010. Epub 2010 Sep 16.
Accurate and reliable estimation of muscle moment arms is a prerequisite for the development of musculoskeletal models. Numerous techniques are available to estimate the Achilles tendon moment arm in vivo. The purposes of this study were 1) to compare in vivo Achilles tendon moment arms obtained using the center of rotation (COR) and tendon excursion (TE) methods and 2) to assess the reliability of each method. For the COR method, magnetic resonance (MR) images from nine participants were obtained at ankle angles of -15°, 0°, and +15° and analyzed using Reuleaux' method. For the TE method, the movement of the gastrocnemius medialis-Achilles tendon junction was recorded using ultrasonography as the ankle was passively rotated through its range of motion. The Achilles tendon moment arm was obtained by differentiation of tendon displacement with respect to ankle angular excursion using seven different differentiation techniques. Moment arms obtained using the COR method were significantly greater than those obtained using the TE method (P < 0.01), but results from both methods were well correlated. The coefficient of determination between moment arms derived from the COR and TE methods was highest when tendon displacement was linearly differentiated over a ± 10° interval (R(2) = 0.94). The between-measurement coefficient of variation was 3.9% for the COR method and 4.5-9.7% for the TE method, depending on the differentiation technique. The high reliabilities and strong relationship between methods demonstrate that both methods are robust against their limitations. The large absolute between-method differences (∼ 25-30%) in moment arms have significant implications for their use in musculoskeletal models.
准确可靠地估计肌肉力臂是构建肌肉骨骼模型的前提条件。目前有许多技术可用于在体测量跟腱力臂。本研究的目的是：1）比较基于旋转中心（COR）和跟腱运动（TE）的两种在体测量跟腱力臂的方法，2）评估每种方法的可靠性。对于 COR 方法，9 名受试者在踝关节角度为-15°、0°和+15°时分别接受磁共振（MR）成像，并采用 Reuleaux 方法进行分析。对于 TE 方法，在踝关节被动运动范围内，采用超声记录腓肠肌内侧头-跟腱止点的运动。通过对跟腱位移相对于踝关节角度运动的求导，采用 7 种不同的求导技术获得跟腱力臂。COR 方法得到的跟腱力臂明显大于 TE 方法（P<0.01），但两种方法的结果相关性良好。当在±10°的间隔内对跟腱位移进行线性求导时，COR 和 TE 方法得到的力臂之间的决定系数最高（R2=0.94）。COR 方法的测量内变异系数为 3.9%，而 TE 方法的变异系数为 4.5-9.7%，取决于求导技术。两种方法的可靠性均较高，且相互间关系较强，表明两种方法均能克服其局限性。两种方法得到的力臂之间存在较大的绝对差异（约 25-30%），这对它们在肌肉骨骼模型中的应用具有重要意义。
