Patient demographic and magnetic resonance imaging evaluation of isolated posterolateral corner knee injuries.

Background: Posterolateral stability of the knee is maintained by capsular, ligamentous and tendinous structures, which collectively are known as the posterolateral corner (PLC). Injuries to the PLC of the knee rarely occur without associated anterior (ACL) or posterior cruciate (PCL) ligament tears. The main objectives of our study were to report patient demographics and magnetic resonance imaging (MRI) findings of patients with isolated PLC injuries.

Methods: This study consists of a retrospective analysis of knee MRI from January 2011 to June 2016, in two hospitals in São Paulo, Brazil, where PLC injuries without associated ACL and PCL injuries were identified in MRI by two radiologists specialized in musculoskeletal injuries. Relative and absolute frequencies were used to describe the injuries of each of the PLC structures in the study cases.

Results: A total of 23 cases of PLC injuries without associated cruciate ligament injuries were identified. The mean age of patients was 32.0±8.1 years and 91% patients were male. The main sport associated with isolated PLC injury was Brazilian Jiu-Jitsu (48%), followed by soccer (35%). MRI evaluations of the knees showed lateral collateral ligament (LCL) injuries in 70% of cases, popliteus tendon injuries in 26% of cases and distal biceps tendon injuries in 30% of cases. The popliteofibular ligament (PFL) was damaged in 83% of cases. An associated ALL injury was observed in 43% of cases.

Conclusions: Isolated PLC injuries occurred mainly in young men when practicing Brazilian Jiu-Jitsu and soccer. The LCL was the most frequently injured larger structure in association, and the capsuloligamentous structures (PFL) were the most frequently injured structures overall. ALL injuries occurred in approximately half of the cases, most often concomitantly with LCL injuries.