Koji J Duncan, Jaclyn N Chopp-Hurley, Monica R Maly

Among a variety of conservative and surgical options to treat anterior cruciate ligament (ACL) injuries, we do not understand which options could potentially prevent knee osteoarthritis (OA). The aim of this systematic review was to examine the evidence pertaining to exercise treatment of ACL injuries in the context of knee OA. Medline, Embase, CINAHL, PubMed, and PEDro (Physiotherapy Evidence Database) databases were systematically searched using keywords encompassed within four primary key terms: knee, osteoarthritis, anterior cruciate ligament, and exercise. Clinical studies evaluating the effect of an exercise treatment for ACL injuries on the development of knee OA in adult humans were included. The PEDro scale was used to critically assess the studies included in the review. Eighteen studies were included in this review, with a median PEDro score of 6/11 (range, 2/11-9/11). Three studies provided statistical evidence that exercise following ACL injury lowered the risk for knee OA development. Nine studies demonstrated no benefit of exercise in preventing knee OA incidence relative to either operative treatment or the contralateral, unaffected knee. However, exercise resulted in higher knee instability. Nonetheless, there were no significant differences in subjective or objective knee outcomes for early versus late ACL reconstruction. This review was not registered through PROSPERO. The relationship between a rehabilitative exercise for ACL injuries and long-term knee OA prevalence is inconclusive. However, research suggests initial conservative treatment with optional late ACL reconstruction because this treatment strategy may reduce the risk of knee OA. More research, ideally randomized controlled trials or comparable designs, is required prior to establishing clinical guidelines for ACL injury management.