Effects of ACL reconstruction surgery on muscle activity of the lower limb during a jump-cut maneuver in males and females

Abstract

We compared muscle activity of the quadriceps, hamstring, and gastrocnemius muscles when ACL-intact (ACL(INT)) and ACL-reconstructed (ACL(REC)) male and female subjects performed a jump-cut task. Surface electromyography sensors were used to evaluate time to peak muscle activity and muscle activity ratios. Rectus femoris (RF) and vastus medialis (VM) peak timing was 71 and 78 ms earlier in ACL(INT) than in ACL(REC) subjects, respectively. Biceps femoris (BF) peak timing was 90 ms earlier in ACL(INT) than in ACL(REC) subjects and 75 ms earlier in females than in males. Medial gastrocnemius (MG) muscle peak timing was 77 ms earlier in ACL(INT) than in ACL(REC) subjects. Lateral gastrocnemius (LG) and MG muscle peak times were 106 ms and 87 ms earlier in females than in males, respectively. The RF, VM, BF, and MG peaked later in ACL(REC) than in ACL(INT) subjects. There was evidence suggesting that the loading phase quadriceps:hamstring (quad:ham) muscle activity ratio was greater in ACL(REC) than in ACL(INT) subjects. Finally, the injury risk phase quad:ham muscle activity ratio was 4.8 times greater in females than in males. In conclusion, differences exist in muscle activity related to ACL status and sex that could potentially help explain graft failure risk and the sex bias.

Keywords: ACL; EMG; injury; muscle; reconstruction.

© 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Figures

Fig. 1

Illustration showing the experimental set up used during this experiment. The subject is pictured performing the jump-cut maneuver. When the subject lands on the force plate they cut and push off to the left (L) or right (R) based on the directional prompt (arrow) directly in front (not shown). A selection of the OMC markers (open circles) and EMG electrodes (black squares) are shown on the subject’s right leg. The EMG electrodes were plugged into the wireless data collection device attached to each subject’s waist.

Fig. 2

Processed, smoothed EMG traces for the RF, VM, ST, BF, LG and MG over the entire length of the activity. The solid and dotted lines represent the time of landing contact and the time of max flexion, respectively.

Fig. 3

(A) Sample processed, smoothed EMG trace for the RF. (B) Trace of the flexion angle of the knee during the jump-cut maneuver. (C) Trace of the ground reaction force during the jump-cut maneuver. For (A), (B), and (C): Assorted dotted and solid lines show the times of: contact, max flexion, and muscle peak. The shaded regions denote the preparatory phase, the loading phase, and the injury risk phase, which encompassed the first 40 ms of the loading phase.

Fig. 4

(A) Bar graph showing the mean peak times for all 6 muscles studied. (B) Bar graph showing the PREP, LOAD, and RISK quad:ham (Q:H) and gastroc:ham (G:H) muscle activity ratios. For (A) and (B): Dotted and solid lines above the bars display p-values for differences between reconstruction status (ACLINT vs. ACLREC) or sex (M vs. F) that were either significant or close to being significant.