Lateral Collateral Ligament Calcification: A Rare and Challenging Cause of Chronic Knee Pain.

Lateral collateral ligament (LCL) calcification of the knee represents an uncommon degenerative or post-traumatic change characterized by ectopic mineral deposition within the ligamentous fibers. We report a rare case of LCL calcification in a 49-year-old female presenting with chronic right lateral knee pain with recurrent acute exacerbations. The patient had a prior history of mild knee trauma, and no significant findings were initially identified on radiographs. Despite several courses of physiotherapy and oral nonsteroidal anti-inflammatory drugs (NSAIDs), her symptoms persisted with only partial relief. Physical examination revealed localized tenderness over the lateral knee compartment and pain with varus stress testing. Bedside ultrasound revealed a well-circumscribed hyperechoic lesion within the LCL consistent with calcific deposition. MRI confirmed the diagnosis. A conservative management plan consisting of radial extracorporeal shockwave therapy (rESWT) was initiated, leading to complete symptom resolution at three-month follow-up.