Partial rupture of the distal biceps brachii tendon: a magnetic resonance imaging analysis

This study is the largest cohort of partial distal biceps brachii tendon ruptures in the literature that was analyzed according to rupture morphology of the long and short tendon heads.

Patients with partial distal biceps tendon ruptures were identified using an institutional enterprise data warehouse query at a single institution. A retrospective chart review was performed to record patient demographics, past medical history, and injury mechanism for each patient. Each patient's magnetic resonance images were reviewed to determine injury patterns, specifically the extent of long head (LH) and short head (SH) tendon involvement, and associated injuries. Rupture morphologies were correlated with mechanism of injury, diabetes status, and smoking history.

Seventy-seven patients were included in the study. The average age was 52 years (±11.9, range: 23-90 years); 67% were male, with an average body mass index of 28.3 (±4.3). A smoking history was reported in 31.2% of patients and 5.2% were diabetic. The partial ruptures were caused by a traumatic mechanism in 57.1% of cases, 23.4% were atraumatic, and 19.5% had an unknown mechanism. The most common injury morphology was a partial LH rupture with an intact SH tendon (33.8%). Isolated complete ruptures of the LH represented the least common injury morphology. Injury morphology was significantly related to mechanism (P < .01). Traumatic ruptures had a higher percentage of SH involvement compared with the atraumatic group (77.3% vs. 37.7%, respectively). In contrast, atraumatic ruptures involved the LH tendon in 89% of cases, with only 37.7% of cases involving the SH tendon. Patients with a history of smoking were more likely to have an atraumatic mechanism (P = .01). A history of diabetes was unrelated to mechanism (P = .20).

Partial ruptures of the distal biceps brachii tendon represent a spectrum of patterns with varying involvement of the LH and SH tendons. Injury morphology was significantly related to mechanism (P < .01). LH tendon involvement was seen in 88.9% of atraumatic cases, whereas SH tendon involvement was seen in 77.3% of traumatic cases. A more comprehensive understanding of partial rupture patterns is critical to further understand the risk factors that may preclude to worse clinical outcomes, and aid in deciding which patients would benefit from operative vs. nonoperative management.