Giant subpatellar synovial osteochondromatosis complicated by osteoarthritis of the knee: A case report.
Chun Zhang, Jiaxin Fu, Zhiqing Chen et al.
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Case in brief
A 71-year-old woman presented with a 2-year history of progressive pain and swelling in her left knee, leading to significant movement restriction and impairment in daily activities. She was diagnosed with giant subpatellar synovial osteochondromatosis (SOC) and severe knee osteoarthritis. Following failed conservative treatment, she underwent mass excision and total knee arthroplasty, resulting in substantial pain relief and improved mobility within 48 hours, with no recurrence at 3-month follow-up.
What made this case unusual
Subpatellar SOC is extremely rare due to the limited synovial tissue in this area, making this case noteworthy for its atypical presentation and significant size.
Diagnostic / clinical pearl
Clinicians should consider synovial osteochondromatosis in the differential diagnosis of calcified subpatellar masses to avoid misdiagnosis.
Why it matters
This case highlights the potential for SOC to develop into a large mass in the subpatellar region, emphasizing the need for awareness of this condition in similar presentations.