Synovial chondromatosis of the foot and ankle.

Background: Synovial chondromatosis (SC) is a benign condition where the synovial lining of joints, bursae, or tendon sheaths undergoes metaplasia and ultimately forms cartilaginous loose bodies. Synovial chondromatosis of the foot and ankle is exceedingly rare, and outcomes following surgical excision are largely unknown.

Materials And Methods: An Institutional Review Board-approved retrospective review of our institution's surgical database from 1970 to 2006 revealed 8 patients with SC of the foot and/or ankle confirmed by pathology.

Results: Eight patients (4 female and 4 male) presented with pain, locking, or stiffness. Average age at presentation was 37 (range, 19 to 60) years. Average followup was 9.5 (range, 1 to 31) years. Six patients had involvement of the ankle, and two, the midfoot. Four patients underwent ankle synovectomy with loose body removal, and were pain-free at last followup. One patient underwent excision and midfoot arthrodesis for severe midfoot destruction. Three patients ultimately underwent below knee amputation, one for multiple recurrences and two for malignant transformation to low-grade chondrosarcoma.

Conclusion: To our knowledge, this is the largest reported series of patients with SC of the foot and ankle. In half the patients, synovectomy with excision of loose bodies resulted in pain free return to normal function, without recurrence, at last followup. However, recurrence occurred in 3 (37.5%) of 8 patients with subsequent malignant transformation to low-grade chondrosarcoma occurring in 2 patients.