In this feature, AAOS Now publishes a series of images, challenging readers to diagnose the condition depicted.
The images for this month’s challenge were submitted by Balaji Govindarajan, MBBS, DOrtho, of Chettinad Health City, India.
Dr. Govindarajan writes that he saw a 13-year-old male with a 4-month history of worsening hip pain and stiffness. The patient had no fever, lymphadenopathy, signs of trauma, or constitutional symptoms. The hip was tender but not warm, with fixed flexion deformity and fixed external rotation deformity of 20 degrees. No true limb length discrepancy was noted. Blood counts, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) counts were normal. AP (Fig.1) and frog leg radiographs and magnetic resonance images (MRI) (Fig. 2A, B) were obtained. What’s your diagnosis?
Find the answer to this month’s challenge below
According to Balaji Govindarajan, MBBS, DOrtho, who submitted the case, the diagnosis is synovial chondromatosis. Following anterior arthrotomy, multiple cartilaginous loose bodies were identified and removed, suggestive of synovial chondromatosis, which was confirmed by histopathologic examination. The affected hip regained nearly full range of movement intraoperatively upon removal of the loose bodies.
Synovial chondromatosis is very rare in children. If the cartilaginous bodies are neither calcified nor ossified, radiographs may fail to suggest the presence of abnormality. MRI is useful in the diagnosis of synovial chondromatosis of the hip, especially in cases in which juxta-articular calcified and/or ossified bodies are not present. Synovial chondromatosis should be considered in differential diagnosis if articular erosions and calcification are present (see preoperative radiograph).
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