Muscle strength and functional performance in patients with anterior cruciate ligament injury treated with training and surgical reconstruction or training only: A two to five‐year followup

Abstract Objective To study muscle strength and functional performance in patients with anterior cruciate ligament (ACL) injury with or without surgical reconstruction 2 to 5 years after injury. Good muscle function is important in preventing early‐onset osteoarthritis (OA), but the role of reconstructive surgery in restoring muscle function is unclear. Methods Of 121 patients with ACL injury included in a randomized controlled trial on training and surgical reconstruction versus training only (the Knee, Anterior cruciate ligament, NON‐surgical versus surgical treatment KANON study, ISRCTN: 84752559), 54 (mean age at followup 30 years, range 20–39, 28% women) were assessed a mean ± SD of 3 ± 0.9 years after injury with reliable, valid, and responsive test batteries for strength (knee extension, knee flexion, leg press) and hop performance (vertical jump, one‐leg hop, side hop). The Limb Symmetry Index (LSI; injured leg divided by uninjured and multiplied by 100) value and absolute values were used for comparisons between groups (analysis of variance). An LSI ≥90% was considered normal. Results There were no differences between the surgical and nonsurgical treatment groups in muscle strength or functional performance. Between 44% and 89% of subjects had normal muscle function in the single tests, and between 44% and 56% had normal function in the test batteries. Conclusion The lack of differences between patients treated with training and surgical reconstruction or training only indicates that reconstructive surgery is not a prerequisite for restoring muscle function. Abnormal muscle function, found in approximately one‐third or more of the patients, may be a predictor of future knee OA.