Hsu A T, Perry J, Gronley J K, Hislop H J
Pathokinesiology Service, Rancho Los Amigos Medical Center, Downey, CA 90242.
Clin Orthop Relat Res. 1993 Mar(288):254-62.
The purpose of this study was to determine the quadriceps demand during single limb stance with the knee in five positions of flexion (0 degree -60 degrees). Two variables were used to estimate the quadriceps demands: the integrated electromyogram (EMG) of three vasti and the torque about the knee joint. Ten normal subjects 23-29 years of age were tested. Myoelectric activity was recorded with intramuscular electrodes and knee joint angle with an electrogoniometer. The EMG data were integrated and normalized. A visible vector system was used to determine knee flexion torque. A significant linear correlation was found between values of patellar ligament force and knee angle (R2 = 0.86). The patellar ligament force increased 4.16% of body weight per degree of knee flexion between 0 degree and 60 degrees. Both vector-estimated quadriceps force and normalized EMG showed significant correlations with knee angle (R2 = 0.91 and R2 = 0.88, respectively). Both exhibited a slower rate of rise below 30 degrees flexion and a higher rate of rise above 30 degrees. The authors' findings suggest that the stabilizing effects of plantar flexors (except gastrocnemius) on the knee joint, changing muscle moment arm length, and force ratio between the patellar ligament and quadriceps muscle with respect to knee angle are primary reasons for the quadratic normalized integrated EMG (NIEMG)-force nonlineality during flexed stance. This might indicate the existence of a critical angle of knee flexion contracture beyond which patients cope poorly with standing and functional ambulation.
本研究的目的是确定在单腿站立时，膝关节处于五个屈曲位置（0度至60度）时股四头肌的需求情况。使用两个变量来估计股四头肌的需求：三块股肌的积分肌电图（EMG）以及膝关节周围的扭矩。对10名年龄在23至29岁的正常受试者进行了测试。使用肌内电极记录肌电活动，用电角度计记录膝关节角度。对EMG数据进行积分和归一化处理。使用可见矢量系统确定膝关节屈曲扭矩。发现髌韧带力值与膝关节角度之间存在显著的线性相关性（R2 = 0.86）。在0度至60度之间，膝关节每屈曲一度，髌韧带力增加体重的4.16%。矢量估计的股四头肌力量和归一化的EMG均与膝关节角度显示出显著相关性（分别为R2 = 0.91和R2 = 0.88）。两者在屈曲低于30度时上升速率较慢，在高于30度时上升速率较高。作者的研究结果表明，跖屈肌（除腓肠肌外）对膝关节的稳定作用、肌肉力臂长度的变化以及髌韧带与股四头肌之间的力比随膝关节角度的变化，是屈曲站立期间二次归一化积分肌电图（NIEMG）-力量非线性的主要原因。这可能表明存在一个膝关节屈曲挛缩的临界角度，超过该角度患者在站立和功能性步行方面的应对能力较差。
