Is There a Correlation Between Knee Extension Peak Torque Quadriceps Maximal Force and Biomechanical Determinants in Hop Tests of the MERItest, 6 months After ACL Reconstruction?

OBJECTIVE: To investigate the relationship between isokinetic knee extension peak torque and specific biomechanical variables during hop tests in patients 6 months postanterior cruciate ligament reconstruction (ACLR). DESIGN: Prospective, cross-sectional study analyzing the correlations between isokinetic knee extension torque and biomechanical outcomes across various functional tests. SETTING: Sports clinic with a specialized biomechanics laboratory. PARTICIPANTS: Sixty-one patients (47 males, 14 females), aged 16 to 55 years, who had undergone ACLR, participated. All met the inclusion criteria and completed the follow-up testing at 6 months postsurgery. ASSESSMENT OF RISK FACTORS: Key independent variables included isokinetic knee extension peak torque. Participants completed standardized functional tests: single-leg and double-leg drop jumps, single-leg hop tests, and double-leg countermovement jumps. MAIN OUTCOME MEASURES: Outcome measures included biomechanical parameters related to dynamic knee stability, including peak knee extensor moments, knee joint power during push-off, peak knee flexion and valgus, and vertical ground reaction force and braking forces. RESULTS: Moderate correlations were observed between knee extension peak torque and select biomechanical variables, including peak knee extensor moments during single-leg drop jumps, knee joint power during push-off phases in both single and double-leg drop jumps, and peak braking forces in single-leg hop tests. However, these relationships suggest that additional factors play essential roles in dynamic stability. CONCLUSIONS: Although quadriceps strength is moderately linked to key biomechanical markers, our findings indicate that a more comprehensive assessment, integrating both strength and biomechanical evaluation, could enhance ACLR rehabilitation strategies. This combined approach may better support recovery and minimize reinjury risk.