Innervation of the Proximal Interphalangeal Joint: An Anatomical Study.

PURPOSE: To describe the innervation of the proximal interphalangeal (PIP) joint of the fingers as well as the anatomical relations of the articular branches.

METHODS: In this anatomical study, 52 fresh-frozen index, long, ring, and little fingers of 6 male and 4 female cadavers were dissected after injection of a colored latex composite. The anatomical dissections were performed under ×3.5 and ×6.0 magnifications. The numbers of articular nerve branches that penetrated the PIP joint on both sides of the fingers were quantified and patterns of innervation were established. We also measured the origin of the branches regarding the PIP articular line, the angle of emergence, and the diameter of the nerves.

RESULTS: The PIP joint was innervated by one articular branch of the proper palmar digital nerve at each side of the finger (pattern 1). Less frequently, an additional distal branch from the same proper palmar digital nerve was found (pattern 2). Dorsal articular branches were identified innervating only the little finger.

CONCLUSIONS: The findings suggest that PIP joints of the fingers have a consistent articular nerve anatomy predominantly provided at the palmar aspect of the joint. These findings provide an anatomical basis for procedures to denervate the PIP joint.

CLINICAL RELEVANCE: An accurate understanding of peripheral nerve anatomy of the PIP joint is essential to improve outcomes in denervation techniques.