Partial tears of the distal biceps tendon: MR appearance and associated clinical findings

Purpose: To describe the magnetic resonance (MR) appearance and associated clinical findings of partial distal biceps tendon tears. Design: Twenty elb ow MR images at 1.5 T, performed over a 7 year period, were reviewed for an appearance of partial tears in the distal biceps. These images were assess ed by two musculoskeletal radiologists for the extent of: (a) abnormal sign al intensity within the tendon, and the presence of (b) bicipitoradial burs itis, and (c) bony microavulsive injury of the radial tuberosity. Medical r ecords for nine of the 20 cases were reviewed for the clinical findings of ecchymosis, trauma, sensation of a "pop", loss of function, and acuity of o nset. Results: Twenty partial distal biceps tendon tears were seen. All dis played an abnormally increased signal in the distal biceps tendon. Three of 20 (15%) showed a 25% to 50% tear, ten of 20 (50%) showed a 50% tear, and seven of 20 (35%) showed a 75% to 90% tear. Bicipitoradial bursitis was see n in I I of 20 (55%) cases. Bony microavulsive injury of the radial tuberos ity was observed in 10 of 20 (50%). Of the nine cases reviewed for associat ed clinical findings, surprisingly, only three (33%) experienced an acute t raumatic episode with an abrupt onset of pain. An insidious onset was repor ted in four of nine (44%). Sensation of a "pop" was recorded in only two of nine (22%) cases. Ecchymosis and loss of function were not seen in any of the cases. Finally, surgical conformation was obtained for three cases. Con clusion: Partial distal biceps tendon tears have a characteristic MR appear ance, demonstrate little functional deficit, and may be attritional in thei r etiology due to the observation of a low number of patients reporting tra uma or an acute onset.