Anatomy of the distal brachioradialis and its potential relationship to distal radius fracture.

PURPOSE: To describe the anatomy of the brachioradialis (BR), paying special attention to its insertion in relation to the surrounding structures in cadavers and evaluating and correlating this information with a distal radius fracture pattern in a clinical population.

METHODS

Eighteen fresh-frozen cadaver arms were dissected to observe the gross anatomy of the BR. The dimensions of the insertion were measured using a caliper and a 3-dimensional digitizer. The radiographs of 34 patients with 35 distal radius fractures were reviewed and the fracture pattern was compared with the normalized location of the BR insertion based on the cadaver measurements.

RESULTS

On average the BR tendon inserted onto the proximal base of the first dorsal compartment 17 mm from the radial styloid tip and extended 15 mm proximally; the insertion was 11 mm wide. The BR insertion was bordered consistently by both septa of the first dorsal compartment, forming a tunnel-like structure of thick fibrous tissue on the radial aspect of the distal radius. The whole length of the tendon attached firmly to the underlying antebrachial fascia, which limited excursion. In 18 of the fractures the fracture line deviated from transverse to proximal at the radial side, forming a radial beak. The proximal tip of the beak correlated with the expected location of the proximal end of the BR tendon insertion.

CONCLUSIONS

The BR distal tendon insertion is a consistent, distinct insertion at the base of the first dorsal compartment, which correlates with the radial-beak fracture pattern in approximately 50% of distal radius fractures. Cutting the BR tendon disconnects the distal fragment from the BR muscle and the forearm fascia, which may facilitate reduction of the distal radial fragments during open reduction of the distal radius fracture.