Electromyographic activity of knee stabilizer muscles during six different balance board stimuli after anterior cruciate ligament surgery.

Abstract

The purpose of this study was to compare the electrical activity of the knee stabilizers, in patients with ACL (anterior cruciate ligament) reconstructed and uninjured individuals during different balance board stimuli. Eleven post-surgery individuals and eleven uninjured controls participated in the study. The muscular activity of the vastus medialis obliquus, vastus lateralis, semitendinosus, biceps femoris and gastrocnemius medial were analyzed by surface electromyography during the execution of six different balance board activities. All electromyographic data were reported as percentage of RMS mean values obtained in maximal voluntary isometric contractions (MVIC) for each muscle. When comparing the individuals with ACL reconstructed and uninjured controls, minor electromyographic activity was observed (MVIC %) for all the muscles in the surgery group (P < 0.05), however, when comparing each exercise between the groups, a statistically significant difference for vastus lateralis was demonstrated in the floor exercise (P = 0.02) and for gastrocnemius on the round board (P = 0.04). Individuals ACL reconstructed presented a decrease in muscular activity during different balance board stimuli, which suggests that compensatory alterations after ACL may still exist even after a surgery to repair an ACL rupture.