Tale of quadriceps and hamstring muscle strength after ACL reconstruction: a systematic review with longitudinal and multivariate meta-analysis.

Adam G Culvenor, Ebonie K Rio, Kay M Crossley, Brooke E Patterson, Michael Hedger, Michael Girdwood, Melissa Haberfield, Jamon Couch, Benjamin Mentiplay

Journal: British journal of sports medicine 2025;59(6):423-434

PMID: 39389762

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Abstract

OBJECTIVE

This study aimed to investigate how knee extensor and flexor strength change over time after anterior cruciate ligament reconstruction (ACLR).

DESIGN

Systematic review with longitudinal meta-analysis.

DATA SOURCES

Medline, Embase, CINAHL, Scopus, Cochrane CENTRAL and SPORTDiscus to 28 February 2023.

ELIGIBILITY CRITERIA

Studies of primary ACLR (n≥50), with mean participant age 18-40 years, reporting a quantitative measure of knee extensor or flexor strength were eligible. Muscle strength had to be reported for the ACL limb and compared with: (1) the contralateral limb (within-person); and/or (2) an uninjured control limb (between-person).

RESULTS

We included 232 studies of 34 220 participants. Knee extensor and flexor strength showed sharp initial improvement postoperatively before tailing off at approximately 12-18 months post surgery with minimal change thereafter. Knee extensor strength was reduced by more than 10% compared with the contralateral limb and approximately 20% compared with uninjured controls at 1 year for slow concentric, fast concentric and isometric contractions. Knee flexor strength showed smaller deficits but was still 5%-7% lower than the contralateral limb at 1 year for slow concentric, fast concentric and isometric contractions. Between-person comparisons showed larger deficits than within-person comparisons.

CONCLUSION

Knee extensor muscle strength is meaningfully reduced (>10%) at 1 year, with limited improvement after this time up to and beyond 5 years post surgery. Many people likely experience persistent and potentially long-term strength deficits after ACLR. Comparison within person (to the contralateral limb) likely underestimates strength deficits in contrast to uninjured controls.

Address: La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora, Victoria, Australia.; La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora, Victoria, Australia.; The Australian Ballet, Southbank, Victoria, Australia.; The Victorian Institute of Sport, Melbourne, Victoria, Australia.; La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora, Victoria, Australia.; Arthritis Research Canada, Vancouver, British Columbia, Canada.; La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora, Victoria, Australia.; Sport, Performance, and Nutrition Research Group, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora, Victoria, Australia.; La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora, Victoria, Australia [email protected].

DOI: 10.1136/bjsports-2023-107977

MeSH Terms: Humans, Muscle Strength, Anterior Cruciate Ligament Reconstruction, Hamstring Muscles, Quadriceps Muscle, Anterior Cruciate Ligament Injuries, Longitudinal Studies, Young Adult, Adult