Traumatic bony avulsion of the lateral collateral ligament of the knee in a pediatric patient.

A 13-year-old struck by a car developed knee swelling and varus instability after treatment of a traumatic brain injury. Magnetic resonance imaging showed a displaced osseous avulsion of the lateral collateral ligament (LCL) from the fibular head with partial biceps femoris rupture, without meniscal or cruciate injury. After arthroscopic exclusion of intra-articular pathology, the fragment was reduced and fixed laterally using two suture anchors and a transosseous stitch, preserving the proximal fibular physis. At 1 year, the knee was stable and radiographs were normal. In displaced pediatric fibular LCL avulsions, prompt recognition and physeal-sparing suture-anchor fixation can restore stability, support early rehabilitation, and minimize growth-disturbance risk.