A rare case of melorheostosis with intra-articular extension causing medial patellar impingement

Area of Science:

• Orthopedics
• Radiology
• Genetics

Background:

• Melorheostosis is a rare, benign skeletal hyperostosis of mesenchymal origin.
• It typically affects long bones, presenting with dense, irregular bone formation resembling candle wax.
• Intra-articular involvement is exceptionally rare.

Observation:

• This case report details a patient with melorheostosis exhibiting intra-articular extension within the knee joint.
• The abnormal bone growth encroached upon the joint space, specifically affecting the medial patellar region.
• The characteristic 'flowing candle wax' appearance was noted on imaging.

Findings:

• The intra-articular melorheostosis led to symptomatic medial patellar impingement.
• This impingement caused pain and restricted range of motion in the affected knee.
• Radiographic and MRI findings confirmed the intra-articular osseous proliferation.

Implications:

• This case expands the known clinical spectrum of melorheostosis.
• It underscores the importance of considering melorheostosis in the differential diagnosis of intra-articular knee masses and pain.
• Further research may elucidate the mechanisms behind intra-articular melorheostosis and its management.