Abstract
Traumatic drill overshoot during dorsal fixation of coronal hamate and fifth metacarpal base fractures risks iatrogenic ulnar nerve injury. This study describes the anatomic relationships between exiting volar drill tips and ulnar nerve branches. Dorsal drilling of hamate bones and fifth metacarpal bases was performed on cadavers. Dorsal hamate bodies were subdivided into 4 quadrants: (1) distal-ulnar, (2) distal-radial, (3) proximal-ulnar, and (4) proximal-radial. Screws measuring 5 mm more than the dorsal-to-volar bone depths were placed in each quadrant to represent drill exit trajectories with consistent overshoot. A single screw was similarly placed 5 mm distal to the midline articular surface of the dorsal fifth metacarpal base. Distances between estimated drill tips and ulnar nerve branches were measured. Ten cadaver hands were examined. The fifth metacarpal base screw tips directly abutted the ulnar motor branch in 6 hands, and were within 1 mm in 4 hands (mean, 0.4 ± 0.5 mm). Distances from the tips to the ulnar motor and sensory branches were largest in the distal-radial quadrant (11.8 ± 0.8 mm and 9.2 ± 1.9 mm, respectively) and smallest in the proximal-ulnar quadrant (7.3 ± 1.5 mm and 4.3 ± 1.1 mm, respectively). Distances to the ulnar motor and sensory branches were similar between the proximal-ulnar and distal-ulnar quadrants, and between the proximal-radial and distal-radial quadrants. Dorsal drilling of coronal hamate fractures appears to be safe, as volar drill tips are well away from ulnar nerve motor and sensory branches. Distances to ulnar nerve branches are largest, and theoretically safest, with dorsal drilling in the distal-radial hamate. Dorsal drilling of fifth metacarpal base fractures appears to carry a high risk for potential ulnar motor nerve injury. These findings may help minimize potential risks for iatrogenic ulnar nerve injury with dorsal drilling of hamate and fifth metacarpal base fractures.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.