Knee flexion and extension force steadiness at 6 months post-acl reconstruction surgery

Major knee ligament injuries, such as ACL injury, cause long-term neuromuscular dysfunctions and morphological changes. Individuals after ACL reconstruction surgery (ACLR) exhibit quadriceps weakness and decreased force steadiness even months after surgery. The current investigation aimed to examine knee flexion and extension force steadiness at submaximal contractions at 6-month post ACL reconstruction surgery. Each subject completed maximal voluntary isometric contractions (MVIC) for knee flexion and extension; then, they were asked to hold 10%, 25%, 35%, and 50% MVIC values (visible in monitor) as steady as possible for 10 sec. Average force and standard deviation in the middle 8 sec was used to calculate coefficient of variation (CoV). Significant group-differences in CoV between the operated limb (OP) and controls were found at Quadriceps 35% and 50% (Quad35/50) in ACLR were larger than controls (P = 0.007-0.033).