Anatomic basis of dorsoradial approach for radioulnar synostosis.

The object of this study was to identify the best approach for exposing the radioulnar interosseous membrane while protecting the posterior interosseous n. (PIN). Twenty paired upper limbs were used to obtain measurements of the PIN and expose the distal two-thirds of the interosseous membrane in the forearm through a dorsoradial approach. The length of the PIN from the radial head to the arcade of Frohse (AF) was 26.5 +/- 1.6 mm in males and 25.3 +/- 1.1 mm in females. The length of the PIN between the radial head and the point where the PIN exits from the supinator was 66.7 +/- 4.7 mm in males and 64.0 +/- 2.5 mm in females. The length of the PIN covered by the supinator was 44.0 +/- 0.5 mm in males and 37.0 +/- 0.5 mm in females. The distance between the point where the PIN exits from the supinator and the lateral margin of the radius was 15.0 +/- 0.9 mm in males and 14.5 +/- 0.9 mm in females. The distance between the exit point of the PIN from the supinator and the lateral margin of the ulna was 18.2 +/- 0.6 mm in males and 17.9 +/- 0.7 mm in females. The distance from the point where the most lateral branch of the PIN entered the abductor pollicis longus (APL) to the lateral margin of the radius was 3.5 +/- 0.5 mm. In 20 cadaveric upper limb, the middle and distal portions of the interosseous membrane were exposed through the interval between the extensor carpi radialis brevis (ECRB) and extensor digitorum communis (EDC) m., after the origin of the extensor pollicis brevis (EPB), and extensor pollicis longus (EPL) mm. had been elevated from the lateral margin of the radius. The present study suggests that using dorsoradial approach facilitates exposure of the middle and distal portions of the interosseous membrane.