[Anatomic relationship between the pronator quadratus and brachioradialis muscle insertion: implications for repair of the muscle after volar plate fixation of distal radius fractures].

BACKGROUND: In open reduction and volar plate fixation of distal radius fractures, the pronator quadratus (PQ) muscle is usually detached at the radial edge of the distal radius. Repair of the muscle is reasonable for coverage of the plate and to maintain normal pronation of the forearm. However, repair of the muscle is not always satisfactory. In this study, the topographic relationship of both the PQ and the brachioradialis muscle (BR) insertions are investigated with regard to optimising the repair of the PQ in open reduction and volar plate fixation of distal radius fractures.

MATERIALS AND METHODS: Twelve forearm pairs fixed in formalin were examined. The muscular boundaries of the PQ and the insertion of the BR were dissected, photographs were taken and measured digitally.

RESULTS: The average distance of the PQ insertion was 4.75 cm. Distally, a close topographic relationship exists between the insertions of both the PQ and BR. A fascial connection of both muscles was detected in all specimens. The average distance of the common insertion was 1.75 cm. After removal of the PQ fascia, 0.85 cm of common insertion remained. In 25 % a muscular connection between both the PQ and BR was detected after removal of the PQ fascia.

CONCLUSION: Both the PQ and BR have a common connective tissue and partially a common muscular insertion. Detaching the PQ insertion with a part of the BR insertion in open reduction and volar plate fixation of distal radius fractures can presumably lead to a more stable repair of the PQ in contrast to a repair within the muscle.