Hughes R E, Niebur G, Liu J, An K N
Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic and Mayo Foundation, Rochester, MN 55905, USA.
J Biomech. 1998 Feb;31(2):157-60. doi: 10.1016/s0021-9290(97)00113-9.
Biomechanical models of the shoulder mechanism require estimates of muscle moment arm magnitude. Some shoulder models have estimated muscle moment arms by assuming an idealized minimum distance path from the origin to insertion that passes around the bony geometry. Alternatively, the principle of virtual work can be used to estimate moment arms from tendon excursion and joint-angle data. The purpose of this study was to determine if these two methods give different estimates of abduction moment arms for the supraspinatus, infraspinatus, and subscapularis muscles. Muscle moment arms were estimated for these muscles on ten fresh frozen cadaver specimens. The results showed a significant difference between the two estimation methods. Average differences were 3.1 mm (10.6%), 3.9 mm (43.9%), and 7.2 mm (70.3%) for the supraspinatus, subscapularis, and infraspinatus muscles, respectively. These results suggest that shoulder models based on the origin-insertion method may give higher rotator cuff muscle force estimates than methods using the slope of the tendon excursion vs joint angle relationship.
肩部机制的生物力学模型需要对肌肉力臂大小进行估计。一些肩部模型通过假设从起点到止点的理想化最短距离路径（该路径绕过骨骼几何结构）来估计肌肉力臂。另外，虚功原理可用于根据肌腱位移和关节角度数据估计力臂。本研究的目的是确定这两种方法对冈上肌、冈下肌和肩胛下肌外展力臂的估计是否不同。在十个新鲜冷冻尸体标本上对这些肌肉的力臂进行了估计。结果表明两种估计方法之间存在显著差异。冈上肌、肩胛下肌和冈下肌的平均差异分别为3.1毫米（10.6%）、3.9毫米（43.9%）和7.2毫米（70.3%）。这些结果表明，基于起止点方法的肩部模型可能比使用肌腱位移与关节角度关系斜率的方法给出更高的肩袖肌力估计值。
