Renström P, Grimby G, Larsson E
Scand J Rehabil Med Suppl. 1983;9:163-73.
The aim of this investigation has been to study the magnitude of the reduction of thigh muscle strength of below-knee amputees and to correlate the strength to the degree of atrophy and to the clinical function. Thirty-two below-knee amputees participated in examinations of the isometric and isokinetic knee extension and flexion strength using an isokinetic dynamometer (Cybex II). The atrophy was evaluated by measuring the mean muscle fibre area on muscle biopsies of the vastus lateralis and the cross-sectional area of the quadriceps and hamstring muscles measured with computed tomography. The isometric and isokinetic knee extension and flexion strength in the amputated leg with and without prosthesis was significantly lower than the strength in the non-amputated leg (p less than 0.01). Knee extension strength was significantly correlated to the mean muscle fibre area of the vastus lateralis. There was no correlation between strength and the cross-sectional area of the quadriceps muscles. There was, however, a significant correlation between the side differences (amputated leg versus non-amputated leg) in isometric knee extension and flexion strength and the side differences in cross-sectional areas. The reduction in isometric and isokinetic knee extension and flexion strength in the amputated leg both with and without prosthesis compared with the non-amputated leg was larger than the reduction in cross-sectional areas of the quadriceps and hamstring muscles and in muscle fibre areas of the vastus lateralis. This indicates that besides muscle atrophy changes in motor unit recruitment pattern may be of importance for the reduction in muscle strength. Isometric and isokinetic knee extension and flexion strength values in the amputated leg with prosthesis were significantly correlated to step length, maximal walking speed and circumference of the thigh. These results indicate that below-knee amputees with a better preserved thigh muscle strength have a good walking capacity.
本研究的目的是探讨膝下截肢者大腿肌肉力量下降的程度，并将该力量与萎缩程度及临床功能相关联。32名膝下截肢者使用等速测力计（Cybex II）参与了等长和等速膝关节伸展及屈曲力量的测试。通过测量股外侧肌肌肉活检的平均肌纤维面积以及用计算机断层扫描测量股四头肌和腘绳肌的横截面积来评估萎缩情况。截肢腿在佩戴和不佩戴假肢时的等长和等速膝关节伸展及屈曲力量均显著低于非截肢腿（p<0.01）。膝关节伸展力量与股外侧肌的平均肌纤维面积显著相关。力量与股四头肌的横截面积之间无相关性。然而，等长膝关节伸展和屈曲力量的侧方差异（截肢腿与非截肢腿）与横截面积的侧方差异之间存在显著相关性。与非截肢腿相比，截肢腿无论是否佩戴假肢，其等长和等速膝关节伸展及屈曲力量的下降幅度均大于股四头肌和腘绳肌横截面积以及股外侧肌肌纤维面积的下降幅度。这表明除了肌肉萎缩外，运动单位募集模式的改变可能对肌肉力量下降也很重要。佩戴假肢的截肢腿的等长和等速膝关节伸展及屈曲力量值与步长、最大步行速度和大腿周长显著相关。这些结果表明，大腿肌肉力量保存较好的膝下截肢者具有良好的步行能力。
