An Unusual Complex Posterolateral Osteoligamentous Injury of the Knee in an Adolescent.

We present an unusual and complex case of a 16-year-old adolescent male who injured his right knee and sustained combined avulsion injuries of posterior cruciate ligament (PCL) at the tibial insertion site, iliotibial band at lateral tibial condyle, and lateral collateral ligament (LCL) at femoral insertion site akin to osteoligamentous posterolateral corner injury. Anatomical reduction of the femoral LCL avulsion fragment was performed and fixed with a two 4-mm partially threaded cancellous screw. Iliotibial band avulsion was buttressed using Ellis t-plate and fixed with two 4-mm partially threaded cancellous screws. PCL avulsion fracture was conservatively treated owing to minimal displacement. At one-year follow-up, the patient was pain free with a range of motion of 0 to 150 degrees of flexion and had a pain free knee with no instability. Posterolateral corner injury in the patient was very significant as it involved LCL avulsion and iliotibial band avulsion, both of which are part of the posterolateral structures of the knee and also involve the growth plate. Fixation of the avulsion of Gerdy's tubercle with the buttress plate helps to provide additional stability to counteract the deforming forces of the iliotibial band. LCL is also the major stabilizer against varus forces, and hence fixation is required for stability while preventing growth disturbance. PCL avulsion can be treated conservatively in those patients where the fragment is undisplaced or minimally displaced. A good outcome can be achieved in skeletally immature patients who have osteoligamentous posterolateral corner injuries with associated avulsion fractures by using appropriate anatomical reduction and surgical fixation.