Wrist denervation of the posterior interosseous nerve through a volar approach: a new technique with anatomical considerations.

Purpose: Full or selective wrist denervation is an effective treatment for chronic wrist pain. In this cadaveric study, a volar approach for prophylactic denervation of the posterior interosseous nerve (PIN) and the anterior interosseous nerve (AIN) was assessed, which can simultaneously be performed during volar approaches for distal radius fracture fixation or in combination with metalwork removal.

Materials And Methods: In total 40 adult upper limbs, embalmed using Thiel's method, were investigated. Group 1 included 20 limbs of which the distances between AIN and PIN to the ulnar margin of radius were measured at levels 6, 8 and 10 cm proximal to the styloid process and the distance radial styloid process to proximal border of pronator quadratus which might be useful as an intraoperative landmark. Subsequently further additional 20 adult limbs (group 2) were used. Transection of the PIN via this volar approach at the evaluated best level of step 1 was performed and evaluated by dissection via a dorsal approach.

Results: In group 1, the PIN runs within the interosseous membrane, from the ulnar border of the radius, 6.4 mm (SD 2.66) at 6 cm, 8.4 mm (SD 2.28) at 8 cm and 3.75 mm (SD 5.46) at 10 cm proximal to the radial styloid. The AIN runs within the interosseous membrane, from the ulna edge of the radius, 7.5 mm (SD 2.4) at 6 cm, 7.3 mm (SD 1.95) at 8 cm and 2.35 mm (3.42) at 10 cm proximal to the radial styloid. AIN and PIN were in close proximity at the 8-cm level which equals a 1-cm distance proximal to the pronator quadratus border. Group 2 showed a successful transection of the PIN through a single volar surgical approach in additional 18 out of 20 adult upper limbs.

Conclusions: This study shows the local anatomy of the PIN, allowing denervation via a volar approach.