Pronation can increase the pressure on the posterior interosseous nerve under the arcade of Frohse: a possible mechanism of palsy after two-incision repair for distal biceps rupture--clinical experience and a cadaveric investigation.

Posterior interosseous nerve palsy is a recognized complication of 2-incision distal biceps tendon repair. We hypothesize that intraoperative forearm pronation can cause compression of the posterior interosseous nerve beneath the supinator and arcade of Frohse. Six human male cadaver upper extremities were dissected. Pressure on the posterior interosseous nerve beneath the arcade of Frohse and supinator was measured with a Swan-Ganz catheter connected to a pressure transducer. Pressure was significantly elevated in maximal pronation in all specimens with the elbow in both flexion and extension. Pressures at full pronation were significantly higher than pressures measured at 60 degrees of pronation (5 +/- 2 mm Hg in 60 degrees of pronation and 90 degrees of flexion, P < .0001; 7 +/- 3 mm Hg in 60 degrees of pronation and extension, P < 005). Maximal pronation can cause increased pressure on the posterior interosseous nerve. The safety of 2-incision distal biceps repair may be increased by avoiding prolonged, uninterrupted periods of hyperpronation.