 Infection of the knee joint following ACL reconstruction is a rare but serious complication. Past studies have attempted to uncover the risk factors that make certain individuals more susceptible to infection than others. But many of these studies have been limited to small and medium-sized cohorts. A new study reported in the American Journal of Sports Medicine has examined the largest single-center cohort to date. Findings reveal that graft type, age, and revision surgery could be linked to risk of infection following ACL reconstruction. The researchers behind the study reviewed more than 11,000 total procedures performed at a single institution between 2010 and 2018. Among these, 48 infections were identified. In addition to infections, the researchers reviewed patient and procedure characteristics associated with infection, infection characteristics, incidents of ACL graft retention, and factors associated with retention versus removal of ACL grafts. A regression analysis designed to link these variables to infection revealed three important risk factors, graft type, revision ACL reconstruction surgery, and younger age. Among graft types, both hamstring autographs and all allographs were independently associated with an increased risk of infection when compared to bone, patellar tendon, bone autographs. No statistically significant differences were found for retained versus removed grafts, besides fewer or more than two irrigations and debridement procedures. Larger cohorts with a greater number of infections following ACL reconstruction are needed to identify factors associated with graft retention versus removal. These and other future findings could provide clinicians a clearer picture of the risks that predispose patients to infection after ACL surgery.