Landing biomechanics in anterior cruciate ligament reconstructed females who pass or fail a functional test battery.

Background: A functional test battery (FTB) has been proposed to determine return to full activity following anterior cruciate ligament reconstruction (ACLR). However, there is little biomechanical evidence of FTB usefulness. The purpose of this study was to compare knee joint landing and cutting biomechanics between ACLR patients who passed (ACLR-Pass), failed (ACLR-Fail), and healthy females (Healthy) before and after exercise.

Methods: Thirty females were included: 10 ACLR-Pass, eight ACLR-Fail and 12 Healthy. Participants performed a FTB consisting of The 2000 International Knee Documentation Committee Subjective Knee Evaluation Form, the Knee Outcome Survey Activities of Daily Living Scale, and quadricep strength and single-leg hop tests. Double-leg jump landing (DLJL) and single-leg jump cutting (SLJC) biomechanics were assessed before and after exercise.

Results: Significant main effects of exercise were found during DLJL: lesser knee flexion angle at initial contact after exercise (before exercise: 15.8 ± 5.0, after exercise: 14.2 ± 5.4, P = 0.01, ηp 2 = 0.25); and during SLJC: smaller peak knee extension moment (before exercise: -0.33 ± 0.1, after exercise: -0.31 ± 0.1, P = 0.02, ηp 2 = 0.18). While there was a significant group by time interaction effect with lesser peak knee flexion angle after exercise, this interaction effect was likely driven by a reduction in peak knee flexion in only the Healthy group.

Conclusions: Healthy females exhibited a reduction in peak knee flexion during SLJC after exercise. However, there were no differences in ACLR knee biomechanics during DLJL and SLJC performed before and after exercise.