A Cadaveric Study of the Posterior Interosseous Nerve and Its Branches at the Level of the Distal Radius

Purpose Posterior interosseous nerve (PIN) damage has been cited as a cause of wrist pain syndrome after distal radius fractures. The goal of this cadaveric study was to examine this hypothesis by looking for branches between the PIN and the periosteum of the distal radius. Methods The PIN was dissected in 10 adult specimens (8 fresh and 2 embalmed) under ×2.5 magnification. All of the dissections started from the last motor branch of the PIN, innervating the extensor indicis proprius, and proceeded from proximal to distal. Results The PIN was divided into 3 terminal segments in the dorsal wrist joint (proximal, middle, and distal segments). We were able to observe that branches to the distal radial periosteum were constant and emerged from the middle segment where the nerve is enclosed in a sturdy fibro-fatty sheath adhered to the dorsal periosteum of the distal radius. No collateral bundle was identified in the proximal segment. In the distal segment, every specimen had branches to the radiocarpal joint; 9 of 10 had a midcarpal innervation. Terminal branches to the carpometacarpal joints were identified in 2 cadaveric wrists. Conclusions The radial periosteum PIN branches consistently identified in these specimens may contribute to dorsal wrist pain seen at the time of late follow-up in patients after distal radius fractures. Clinical relevance The benefit of PIN denervation as an adjuvant procedure should be evaluated further in the surgical management of wrist injuries.