Calcification of the Lateral Collateral Ligament of the Knee: A Case Series

Calcification of the lateral collateral ligament (LCL) of the knee is a rare cause of lateral knee pain related to hydroxyapatite crystal deposition. We report a case series of four patients presenting with lateral knee pain. Diagnosis was established using imaging. In one case, calcification was first detected on ultrasound and subsequently confirmed on radiography and MRI. In two other cases, calcification was identified on radiography and MRI, with spontaneous radiographic resolution on follow-up in one patient. In the fourth patient, dual-energy CT was additionally performed to exclude gout. All patients were treated conservatively with nonsteroidal anti-inflammatory drugs and physiotherapy, with symptomatic improvement. Our findings suggest that plain radiography is usually sufficient to identify LCL calcification, while advanced imaging aids in excluding other diagnoses and in assessing associated soft-tissue changes. Most patients can be managed conservatively, and spontaneous resolution of calcification may be observed in some cases.