Risk Factors for Contralateral ACL Injury: A Single Institution Case–Control Study

Our purpose was to evaluate if there is any association between requiring contralateral anterior cruciate ligament (ACL) reconstruction and various: (1) demographics, (2) patient characteristics, and (3) surgery-specific factors. A prospectively collected database at a single institution was queried to find all patients who underwent primary ACL reconstruction between 2012 and 2014. We identified 312 primary ACL reconstruction patients with a mean age of 24 years and a mean follow-up of 3 years (range, 2–5 years). This cohort was compared with all those who had primary ACL reconstructions during the same time period without a contralateral procedure. We evaluated: (1) incidence, (2) demographic variables, (3) family history, (4) graft choice, (5) activity causing injury, and (6) mechanism of injury (contact versus noncontact). There were 16 patients (4.8%) with a mean age of 21 years and a mean follow-up of 3 years that required a contralateral reconstruction. More females required contralateral reconstruction when compared with the control cohort ( p  = 0.049). However, there was no difference in the mean age between the cohorts ( p  = 0.32). Those who underwent reconstruction using a tibialis anterior allograft were far more likely to require a contralateral reconstruction ( p  = 0.0002). Bone-tendon-bone patellar autograft ( p  = 0.16), hamstring autograft ( p  = 0.76), and hamstring allograft ( p  = 0.68) had similar incidences of contralateral ACL injury. Lacrosse was associated with higher risk of contralateral procedure ( p  = 0.03). Mechanism of injury had no association of contralateral reconstruction ( p  = 0.71). We found that those with the highest risk of contralateral ACL reconstruction following their index procedure were females, those with tibialis anterior allografts, and those who had their ipsilateral injury while playing lacrosse. These data may be used by practitioners when educating patients regarding their potential for requiring a contralateral reconstruction following their index procedure.