K-Wire Fixation of Metacarpal and Phalangeal Fractures: Association Between Superficial Landmarks and Penetration of Structures Surrounding the Metacarpophalangeal Joint

Abstract

Purpose: There is little information regarding the starting points for intramedullary K-wires and their effect on the soft tissues surrounding the metacarpophalangeal (MCP) joint. This study attempted to identify starting points for intramedullary K-wire fixation and determine the effect of these K-wires on soft tissues surrounding the MCP joint. Methods: We placed intramedullary K-wires in the index, middle, and little finger metacarpals and proximal phalanges in 6 cadaveric specimens. We measured the starting points of the K-wires and performed dissection to evaluate which structures were penetrated. A Fisher exact test determined statistical significance between K-wire penetration of soft tissue structures and the starting point for K-wires. Results: Metacarpal K-wires started 8.5 ± 1.5 mm volar to the dorsal aspect of the metacarpal head, 19.1 ± 4.6 mm proximal to the digital palmar crease, and 8.6 ± 1.2 mm from the metacarpal head midline. All MCP K-wires crossed at least one soft tissue structure about the MCP joint; the most commonly the sagittal band. Proximal phalanx K-wires started 8.9 ± 2.9 mm proximal to the distal aspect of the metacarpal head, 25.5 ± 5.9 mm proximal to the digital palmar crease, and 9.9 ± 1.5 mm from metacarpal head midline. All proximal phalanx K-wires crossed at least one soft tissue structure about the MCP, most commonly the joint capsule. No relation was established between K-wire start point and penetration of soft tissue structures. Conclusions: Use of these measurements may aid the physician in placing intramedullary K-wires into the proximal phalanges and metacarpals. Starting points that decrease the rate of penetration of soft tissue structures around the MCP joint have not been described, and all pins crossed at least one soft tissue structure adjacent to the MCP joint. Type of study/level of evidence: Therapeutic IV Key words: complication, fracture, K-wire, metacarpal, phalangeal