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Figure. Radiograph of elbow of an adolescent taken after a fall.
A 16-year-old adolescent presents with right elbow pain after a fall 2 days ago. She was walking to the bus when she tripped on ice and landed on the elbow. Since then, her pain has improved significantly but her mother wants her to be evaluated. The patient denies a history of numbness or cold insensitivity to the hand and forearm. On physical examination, the patient has no swelling or bruising to the elbow and slight tenderness to palpation over the olecranon. Radiographs of the elbow show no evidence of a fracture, however, she has a hook-shaped bony mass on the supracondylar aspect of her proximal humerus (Figure).
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Benign bone growths that extend outward from normal bone (exostosis) are often seen incidentally on radiographs. The most common exophytic lesion diagnosed incidentally is an osteochondroma. The classic findings of an osteochondroma include a pedunculated bony lesion in the metaphyseal region that projects away from the nearby joint.1,2
A supracondylar process (or spur) on the anteromedial aspect of the humerus (about 5 cm proximal to the medial epicondyle) has similar radiographic findings and can be confused with an osteochondroma. A fibrous band of tissue known as the ligament of Struthers attaches to the process and can cause symptomatic compression of the median nerve and/or brachial artery. The lesion should be differentiated from an osteochondroma.1,2
The patient’s radiograph shows the exostosis pointing toward the joint whereas an osteochondroma generally points away. The humeral cortex is continuous with an osteochondroma cortex whereas the humeral cortex is intact with a supracondylar process.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
References
1. Mutnuru PC, Perubhotla LM. Rare mimickers of exostosis: a case series. J Clin Diagn Res. 2016;10(7):TR06-7. doi:10.7860/JCDR/2016/18794.8193
2. Shivaleela C, Suresh BS, Kumar GV, Lakshmiprabha S. Morphological study of the supracondylar process of the humerus and its clinical implications. J Clin Diagn Res. 2014;8(1):1-3. doi:10.7860/JCDR/2014/6743.3915
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