summary Synovial Chondromatosis is a proliferative disease of the synovium associated with cartilage metaplasia that results in multiple intra-articular loose bodies. The condition usually presents in patients between 30 and 50 years of age with localized joint pain, stiffness, and swelling. Diagnosis is made on radiographs in late disease but MRI studies may be required in early disease to show cartilage nodules throughout the joint space. Treatment is usually observation for mild symptoms without restriction in motion. Open or arthroscopic synovectomy and loose body resection is indicated for patients with progressive pain, loss of motion, and reduced function. Epidemiology Demographics usually affects young adults 30-50 years of age 2:1 male to female ratio Anatomic location knee is most common location Etiology Mechanism associated with cartilage metaplasia results in multiple intra-articular loose bodies ranges from synovial tissue to firm nodules of cartilage Genetics occasional chromosome 6 abnormalities have been found Presentation Symptoms slow progression of symptoms pain and swelling pain worse with activity mechanical symptoms including stiffness can occur in the bursa overlying an osteochondroma Physical exam decreased range of motion can have warmth, erythema, or tenderness Imaging Radiographs recommended views standard AP/lateral of affected joint findings variable depending on stage of disease may show stippled calcification MRI initially cartilage nodules are only visible on MRI lobular appearance in later stage, signal drop out consistent with calcification Studies Histology discrete hyaline cartilage nodules in various stages of calcification and ossification chondrocytes mild atypia binucleate cells occasional mitoses Treatment Nonoperative observation indications mild symptoms not affecting range of motion Operative open or arthroscopic synovectomy and loose body resection indications severe symptoms affecting range of motion outcomes treatment is symptomatic but may help prevent degenerative joint changes