Neuromuscular function after reconstruction of anterior cruciate ligament--a case study using evoked electromyography

To clarify the neuro-muscular function of a lower extremity after reconstruction of anterior cruciate ligament (ACL), we studied the alteration of H reflex and Silent period (SP) from the soleus muscle in a patient with ACL reconstruction. Subject was an eighteen year-old male and high school basketball player after a reconstruction of right ACL. Recording of H reflex and SP was started at one month after operation, and ended at six months post operation with a test at every month. As a result of this study, the amplitude ratio of H/M(max) was increased at post four months after ACL reconstruction on operative side. Little variation of SP was acquired in non-operative side. However, that in operative side was increased compared with non-operative side and gradually decreased until post six months. Post six months, the variation of SP in operative side was recovered as that of non-operative side. And, on the operation side, long-latency reflex (LLR) was appeared during SP from one month to five months after, especially its appearance pattern was most markedly post four months. However, post six months, LLR disappeared during SP. The result of H reflex, SP and LLR appearance suggested a following hypothesis; until post six months after ACL reconstruction, even the small and simple task (i.e. an ankle planter flexion with a slight effort) needs to an intervention of a various supra-spinal function. In this case, autonomy of central nervous system related to an out-put mechanism in lower-extremity was acquired post six months.