Abstract
BACKGROUND: Partial distal biceps tears can occur in the short and/or long heads, leading to forearm pain and weakness. Yet, the pathoanatomy of atraumatic and traumatic partial tears are not understood. The goals of this study are to determine the distal biceps partial tear frequency and tear pattern in a cohort of cadaveric specimens. METHODS: Fifty three fresh frozen cadavers (average age 70.4 ± 13.8 years, range 32-94) underwent elbow endoscopy to screen for partial tears. The partial tendon tear pattern was classified into either attritional (atraumatic), detachment on the tendon's lateral side, or avulsion (traumatic) rupture of the tendon fibers from bone on both the lateral and medial sides. The specimens were dissected and laser scanned to make 3D models. The tear location, shape, and area were calculated using gross dissection and the 3D models. RESULTS: Atraumatic partial distal biceps tears were identified in 40% of the specimens, 72% involved both the long and short heads, 14% long head, and 14% short head. In all tears, the tendon fibers were only detached from the lateral side. The greatest tear width occurred near the short and long head junction. CONCLUSION: Atraumatic partial distal biceps tears are common. The tear originates on the lateral side of the tendon at the short and long head junction. All the tear patterns are attritional and no specimen had surgical treatment. This finding supports the current treatment recommendation of an initial period of nonoperative care for symptomatic atraumatic partial distal biceps tears.