Anatomy of the distal biceps tendon: an invivo 3-T magnetic resonance imaging study.

Abstract

On the basis of the current literature, the optimal surgical technique for distal biceps tendon tears remains controversial. Cadaveric studies have investigated distal biceps anatomy but are limited by cohort size and tissue factors. We sought to investigate distal biceps anatomy invivo by retrospectively reviewing magnetic resonance imaging (MRI) scans. An improved understanding of the anatomy of the distal biceps tendon will lead to better definition of the optimal anatomic surgical repair. Two independent observers retrospectively reviewed 3-T MRI scans of elbows. Basic demographic data were collected, and measurements of tendon length, footprint width, footprint length, and footprint angle were taken using simultaneous tracker lines and a standardized technique. From the biceps muscle belly distally, the presence of a single tendon or double tendons was recorded and the tendon interdigitation point was measured if relevant. A total of 106 3-T MRI scans of 106 elbows of 103 patients were included. There were 71 male and 32 female patients, and the mean age was 44.7 years. Most distal biceps tendons exited the biceps muscle belly as separate entities (91%, 96 of 106 elbows) and then coalesced prior to insertion on the radial tuberosity (91%, 87 of 96 elbows). There was a positive correlation between tendon length and footprint length (P<.05), as well as between tendon length and footprint width (P<.05). The mean tendon length was 65.2 mm (95% confidence interval [CI], 63.3-66.8 mm; range, 44.3-86.8 mm), the mean distance from the musculotendinous junction to the interdigitation point was 38.3 mm (95% CI, 35.8-40.9 mm; range, 8.9-64.8 mm), the mean footprint width was 10.3 mm (95% CI, 9.9-10.7 mm; range, 5.9-16.3 mm), the mean footprint length was 16.2 mm (95% CI, 15.6-16.9; range, 7.3-25.4 mm), and the mean footprint angle was 32.1° (95% CI, 29.5°-34.6°; range, 8.5°-84.3°). An invivo, high-resolution study of the anatomy of the distal biceps tendon improves our understanding of its complex morphology and hence our ability to perform an anatomic "footprint repair."