Effect of elbow flexion on the proximity of the PIN during 2-incision distal biceps repair.

The posterior interosseous nerve (PIN) is at risk for injury during surgical dissection for distal biceps repair, yet the optimal position of elbow flexion to avoid a PIN injury has never been established for the 2-incision approach. The purpose of this study was to determine the proximity of the PIN to the radial tuberosity during surgical dissection in different degrees of elbow flexion. Ten cadaveric specimens with an intact elbow and forearm were dissected in full pronation using a modified Boyd-Anderson approach. Half of the dissections were completed in 90° of flexion and the other half were completed in maximal flexion. To simulate the location of the PIN during a single-incision biceps repair, the distance of the PIN to the radial tuberosity was recorded in full extension and supination. Results from these measurements were assessed for differences using paired t tests, with differences deemed significant for P values less than .05. The PIN was not identified in any of the 2-incision surgical dissections. Based on these findings, the proximity of the PIN to the radial tuberosity is not significantly affected by the degree of elbow flexion in the muscle-splitting 2-incision approach. In addition, a safe zone exists for avoiding PIN injury in a single-incision technique for distal biceps repair because a drill bit exiting the radial tuberosity greater than 1 cm in a distal-radial direction would place the PIN at risk.