Predictors of a Second Anterior Cruciate Ligament Injury Following Reconstruction: A Systematic Review

Return to sport following anterior cruciate ligament (ACL) reconstruction (ACLR) exposes individuals to risk of a second ACL injury. A possible explanation for this risk is the limited consensus regarding standardized criteria used to evaluate readiness for a safe return to sport. The aim of this systematic review was to synthesize existing literature concerning predictors of a second ACL injury. A systematic literature search was conducted between September 10, 2019, and September 13, 2019, using the PubMed, SPORTDiscus, and Scopus databases. Demographic information and predictors of a second ACL injury were extracted from each study included in the review. Six prospective studies met the inclusion criteria. Knee injury and Osteoarthritis Outcome Score-Quality of Life, the shortened version of the Tampa Scale of Kinesiophobia, and hamstring/quadriceps ratio were found to predict ipsilateral graft rupture. Predictors of a second ACL injury to either limb were identified as net hip internal rotator moment impulse, greater frontal plane knee range of motion, greater knee moment asymmetry in sagittal plane, deficits in postural stability, and patients classified as high-risk based on their performance in the triple hop for distance. Finally, the low quadriceps strength limb symmetry index was found to predict all acute knee reinjuries. The findings of this systematic review identified relevant predictors based on self-reported and objectively measured outcomes identifying the risk of a second ACL injury. The findings contribute guidance to clinicians toward relevant predictors that should be involved in an efficient decision-making process concerning a safe return to sport.