Background and Aim: ACL injury is one of the most common sport injuries which undergo reconstructive surgery. Electromyography or recording of muscles’ electrical activity is a suitable means to assess changes in motor control system output. The goal of this study is to compare the lower limb muscles EMG activity during drop landing in individuals after ACL reconstruction and healthy subjects.

Materials and Methods: Eleven men who had undergone ACL reconstruction 6 to 24 months ago (Age 29±6 years old) and 11 healthy men (Age 28±2 years old) participated in the study. Amount of electrical activity for tibialis anterior, vastus medialis, vastus lateralis, semitendinosus and biceps femoris muscles was recorded using surface electrodes during drop landing and calculated for two time intervals. The amount of activity was measured in -150 to +50 and +50 to +180 intervals in relation to the landing moment. Subjective IKDC questionnaire and cross-over hop functional test were used to determine the subjective and objective functional level.  Independent t test was used to determine between-group statistical differences.

Results: Feed forward activity of semitendinosus (P=.041) and biceps femoris (P=.008) muscles were significantly higher in ACLR group and feedback activity of vastus medialis (P=.03) muscles was significantly lower in ACLR group. Healthy individuals showed higher score on both the functional test and IKDC questionnaire. (P<.0005)

Conclusion: Individuals who had undergone reconstructive surgery of ACL showed different muscular activity compared to healthy subjects and closer to ACL deficient individuals 6 months after surgery and routine rehabilitation.

Keywords: Anterior cruciate ligament reconstruction, Electromyography, Neuromuscular control