Contact Versus Noncontact Anterior Cruciate Ligament Injuries: Is Mechanism of Injury Predictive of Concomitant Knee Pathology?

<bold>Purpose: </bold>To determine if mechanism of injury is predictive of concomitant knee pathology found at the time of anterior cruciate ligament (ACL) reconstruction.<bold>Methods: </bold>All patients aged 16 to 35 who underwent ACL reconstruction at our institution between January 2009 and December 2015 were retrospectively reviewed. Mechanism of injury was determined from patient history. The presence of meniscal or chondral damage was determined from operative records, while collateral ligament injuries were determined by the treating surgeon's diagnosis after physical examination and their review of magnetic resonance imaging findings. Patients with inadequate documentation, history of a subsequent instability episode following the initial injury, or prior history of knee pathology were excluded.<bold>Results: </bold>Six hundred eighty-seven patients (169 contact and 518 noncontact) were included. A 2-fold increase in the incidence of collateral ligament injury was identified between the 2 groups with 114 (67.5%) in the contact group and 175 (33.8%) in the noncontact group (P < .001). Twenty-six patients (15.4%) in the contact group compared with 9 (1.7%) in the noncontact group had a grade III collateral ligament injury (P < .001). Chondral injury was identified in 41 (24.3%) patients in the contact group and 87 (16.8%) in the noncontact group (P = .05) with 9 (5.3%) grade IV lesions in the contact group and 4 (0.8%) in the noncontact group (P < .001). Eleven patients in the contact group (6.5%) and 15 in the noncontact group (2.9%) had a chondral injury to the lateral femoral condyle (P = .04).<bold>Conclusions: </bold>Although we found no difference in the incidence or type of meniscal tears, we found a significant increase in the incidence of grade IV chondral injury, chondral injury to the lateral femoral condyle, and grade III collateral ligament damage in the setting of contact ACL injuries. This knowledge can aid surgeons in preoperative planning and patient counseling.<bold>Level Of Evidence: </bold>Level III, retrospective comparative study. [ABSTRACT FROM AUTHOR]