Case Report: Combined anterior and posterior open synovectomy for recurrent primary synovial chondromatosis of the knee in a female young adult

Synovial chondromatosis is an uncommon, benign condition in which the synovium forms cartilage nodules that can break off and become loose bodies inside a joint. It usually affects a single large joint and often causes pain, swelling, mechanical symptoms, and loss of motion. The diagnosis is often suggested by history, physical examination, and imaging findings, but confirmation depends on histopathology. Due to disease rarity, it is often misdiagnosed or recognized late. We describe a 21-year-old woman with recurrent and progressive left knee primary synovial chondromatosis after incomplete open excision performed following functional limitation. She returned with worsening pain, stiffness, and knee arc of motion of only 30°–50°. Imaging showed diffuse synovial thickening and numerous ossified loose bodies filling both the anterior and posterior compartments of the knee. Given the extent of disease and failure of prior surgery, we performed open synovectomy using an anterior medial parapatellar approach and a posterior lazy-S approach, allowing compartment visualization and removal of loose bodies and diseased synovium. Histopathology confirmed synovial chondromatosis without malignant features. Her recovery was uneventful, with marked pain relief and improved gait and range of motion of 0°–115°. This case shows that recurrent, compartment-spanning disease may require a tailored open approach. Combined anterior and posterior synovectomy achieved symptomatic and functional improvement in selected cases. Posterior-compartment disease should be considered and addressed if present at the index operation; leaving it in situ led to recurrence and subsequent revision.