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Yan, Xian He (John)

University of British Columbia

Anterior cruciate ligament (ACL) tears and subsequent ACL reconstruction (ACLR) surgery are associated with a recalcitrant decline in quadriceps muscle performance which contribute to impaired knee function, elevated osteoarthritis risk, and poor quality-of-life. Little is known about why this occurs, or how to prevent it. One important component of quadriceps muscle performance that may be impacted by an ACL tear or ACLR and shed light on this phenomenon is the ability to rapidly contract and produce force or ‘explosive neuromuscular performance’ (ENP). This cross-sectional study assessed between-limb difference in quadriceps muscle ENP and its determinants of individuals aged 18-40 years, 9-48 months past a primary ACLR. ENP was measured as isometric torque (Nm) at 90° flexion (computerized dynamometry) 0-200 ms (in 25 ms increments, ENP₁₀₀ as primary outcome), after the first electrical onset of any quadriceps muscle (electromyography). Secondary outcomes included between-limb differences in knee extension rate of torque development (RTD; average Nm/s 0-50 ms after torque onset) and electromechanical delay (ms; time from electrical to torque onset). A mixed-model regression assessed between-limb differences for all outcomes, adjusted for graft harvest site and sex. 35 participants (mean±SD age 27.7±5.8 years, 54% female, median; inter-quartile range 19.4; 11.3-29.7 months post-ACLR) completed this study. No between-limb differences in quadriceps muscle ENP₁₀₀ (-2.2 Nm; 95%CI -6.4, 2.1) and electromechanical delay (-0.1 ms; 95%CI -4.2, 4.0) were observed. However, compared to the contralateral limb, the ACLR limb had lower ENP between 125-200 ms after electrical onset, lower RTD₀₋₅₀ (-82.9 Nm; 95%CI -164, -2.2), and lower peak torque values (-41.6 Nm; 95%CI -56.8, -26.4). Taken together, these findings suggest that there are deficits in quadriceps muscle ENP, RTD, and peak torque present beyond 9-months post-ACLR and that neural excitation and persistent muscle atrophy may be important avenues for future research.

Text

2025-06-09

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/91316

Rehabilitation Sciences

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/