Medial quadriceps cyst associated with bipartite patella – a case report

Introduction: Bipartite patella is an anatomical variant that is often asymptomatic but may cause anterior knee pain or mechanical symptoms. Cystic formations originating from a bipartite patella are exceptional and therefore poorly documented. Presentation of the case: A 56-year-old man presented with a painful, mobile 6 × 2 cm mass in the left vastus medialis (VM) muscle that had been evolving for 2 years. Radiography revealed a bipartite patella. Magnetic resonance imaging showed a homogeneous T2-hyperintense lesion within the VM that was fed via a defect between the layers of the quadriceps tendon (QT) and was associated with subchondral bone edema of the bipartite patella. Surgical management consisted of medial cyst excision, resection of the superolateral patellar ossicle, and QT revision. Discussion and conclusion: This uncommon presentation demonstrates a cyst arising due to mechanical conflict in a bipartite patella, with QT defects acting as a communication pathway. The case underscores diagnostic and therapeutic challenges in managing such cysts, highlighting the role of imaging in diagnosis and in guiding surgical intervention.