Sonography of partial-thickness tears of the distal triceps brachii tendon.

OBJECTIVES The purpose of this study was to retrospectively characterize the sonographic appearance of partial-thickness distal triceps brachii tendon tears. METHODS After Institutional Review Board approval, sonographic records were searched for patients who had an unequivocal partial-thickness triceps tendon tear at surgery or magnetic resonance imaging. Sonograms were retrospectively characterized for tendon discontinuity of the superficial or deep layers, tendon retraction, osseous fracture fragments, and joint effusion. Imaging findings were then compared with clinical, imaging, and surgical results. RESULTS Five patients had a partial-thickness distal triceps brachii tendon tear at surgery (n = 4) or magnetic resonance imaging (n = 1). All cases only involved the superficial tendon layer (combined long and lateral heads) with retraction of a fractured olecranon enthesophyte fragment. The deep tendon layer (medial head) was intact in all cases with no joint effusion. CONCLUSIONS Partial-thickness distal triceps brachii tendon tears have a characteristic appearance with selective superficial tendon retraction and olecranon enthesophyte avulsion fracture.