Insertional anatomy and clinical relevance of the distal biceps tendon

PURPOSE: This study was undertaken to evaluate the incidence of bifurcated distal biceps tendons and the tendon's insertional footprint on the radial tuberosity. METHODS: Twenty-five embalmed cadaveric specimens were dissected. The relationships and orientation of the muscle bellies and distal biceps tendon were examined. The insertional length, width, and footprint area of the distal biceps tendon on the radial tuberosity were evaluated. RESULTS: In 12 specimens (48%), the distal biceps tendon was in 2 distinct, easily separated parts. The average footprint length, width, and area of the tendon's insertion on the radial tuberosity were 20.5 mm ± 2.0 mm, 9.7 mm ± 1.3 mm, and 156.3 mm(2) ± 29.4 mm(2), respectively. We calculated that the tendon's insertion occupied approximately 35.9% of the area of the radial tuberosity. In the specimens with a bifurcated distal biceps tendon, the long head of the tendon inserted at the posterosuperior portion of the radial tuberosity, and the average area was 71.4 mm(2) ± 11.3 mm(2). The short head of the distal biceps tendon inserted at the anteroinferior portion, and the average area was 88.3 mm(2) ± 24.1 mm(2). CONCLUSION: This study confirmed that bifurcated distal biceps tendon insertion is not a rare anatomical variation, showed by recent investigations, and found that the short head of the distal biceps tendon was inserted more anteriorly than the long head on the radial tuberosity. These findings may allow functional independence and isolated rupture of each portion. It can make correct diagnosis possible and allow for a more anatomical orientation of the tendon during surgical repair.