The impact of anterior cruciate ligament deficiency and reconstruction on bilateral thigh muscle activity during stair descent

Abstract

Aim: To assess electromyographic (EMG) gait pattern changes during stair descent in subjects with chronic anterior cruciate ligament (ACL) deficiency, and in subjects after ACL reconstruction. Methods: Thirteen ACL deficient subjects (ACLdef), 8 ACL reconstructed subjects (ACLrec), and 10 controls (CON) participated in the study. All subjects were assessed for functional and lean thigh volume (LTV) differences in the injured and uninjured limb. All subjects then stepped off a bench with EMG electrodes on the vastus medialis, vastus lateralis and hamstrings muscles of both limbs. Results: Step down activity caused similar EMG responses in the injured and supporting limb in the ACLdef group compared to that in the control group. In contrast, in the ACLrec group, the onset of EMG activity occurred earlier during the step down activity in the vastus medialis and vastus lateralis of the supporting limb. There was significantly greater EMG activity in the vastus lateralis and hamstring muscles of the supporting limb (p < 0.05) in the ACLrec group compared to ACLdef and control groups. The changes in EMG activity did not appear to be related to differences in LTV, since greater LTV deficits were present in the ACLdef compared to the ACLrec group (p < 0.01). Conclusions: In ACL reconstructed subjects, changes in muscle recruitment patterns in the supporting limb during step down activity have been identified. This altered activity pattern was not present in the supporting limb of ACL deficient subjects

Keywords

• gait pattern activity
• step down
• EMG