Aune A K, Ekeland A, Nordsletten L
Institute for Surgical Research, Rikshospitalet, National Hospital, University of Oslo, Norway.
Acta Orthop Scand. 1995 Jun;66(3):261-5. doi: 10.3109/17453679508995538.
We studied the effect of quadriceps or hamstring contractions on the anterior tibial shear load to anterior cruciate ligament failure in an in vivo rat model. In both knees of 20 Wistar rats the joint capsule and ligaments, except the anterior cruciate ligaments, were cut and the menisci resected. In 10 rats the right ligament was loaded to failure by anterior translation of the tibia relative to the femur in a testing device during hamstring contraction induced by electrical stimulation of the ischiatic nerve. In the other 10 rats, the right ligament was loaded to failure correspondingly during quadriceps contraction induced by electrical stimulation of the femoral nerve. The loading rate was 2.5 mm s-1 (approximately 0.6(-1)). The knee flexion during testing was 30 degrees. As control, the anterior cruciate ligament of the left knee was loaded correspondingly with relaxed muscles. The ultimate load for the ACL tested during hamstring contraction was 1.5 times higher than when tested with the hamstrings relaxed, more than double the energy was absorbed at failure and the linear stiffness was 1.2 times higher. During testing with quadriceps contraction, no differences in the structural properties were found, compared to testing with the quadriceps relaxed. Our findings show that hamstring contraction helps to resist anterior tibial shear force at 30 degrees knee flexion in rats thus protecting the anterior cruciate ligaments. Quadriceps contraction in this situation does not affect anterior shear force to ligament failure.
我们在大鼠活体模型中研究了股四头肌或腘绳肌收缩对前交叉韧带失效时胫骨前向剪切负荷的影响。在20只Wistar大鼠的双膝关节中，除前交叉韧带外，切断关节囊和韧带，并切除半月板。在10只大鼠中，通过坐骨神经电刺激诱导腘绳肌收缩，在测试装置中使右膝前交叉韧带因胫骨相对于股骨的前向平移而负荷至失效。在另外10只大鼠中，通过股神经电刺激诱导股四头肌收缩，右膝前交叉韧带相应地负荷至失效。加载速率为2.5 mm/s（约0.6（-1））。测试期间膝关节屈曲角度为30度。作为对照，左膝前交叉韧带在肌肉松弛状态下进行相应加载。在腘绳肌收缩时测试的前交叉韧带的极限负荷比腘绳肌松弛时测试的高1.5倍，失效时吸收的能量增加了一倍多，线性刚度高1.2倍。在股四头肌收缩测试时，与股四头肌松弛测试相比，未发现结构特性有差异。我们的研究结果表明，在大鼠膝关节屈曲30度时，腘绳肌收缩有助于抵抗胫骨前向剪切力，从而保护前交叉韧带。在这种情况下，股四头肌收缩不影响韧带失效时的前向剪切力。
