Two-incision Approach for the Open Reduction Internal Fixation of Intra-articular Hamate Body Fractures Using a Cannulated Headless Compression Screw

Dorsal Fixation of Coronal Hamate and Fifth Metacarpal Base Fractures: An Anatomic Evaluation of the Ulnar Nerve

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

CLINICAL RELEVANCE

These findings may help minimize potential risks for iatrogenic ulnar nerve injury with dorsal drilling of hamate and fifth metacarpal base fractures.

Hamate Body Fractures: a Comprehensive Review of the Literature

PURPOSE OF REVIEW

Due to the rarity and often discrete nature of hamate body fractures, timely diagnosis requires a high level of suspicion on the part of the clinician. Here, the authors have compiled the findings from 6 cohort studies and 33 case reports describing hamate body fractures in order to summarize the natural history, management, and outcomes of these infrequent injuries.

RECENT FINDINGS

Fractures of the hamate body typically occur in the coronal plane through axial loading of the metacarpals or loading in the transverse plane by a compressive force. Standard radiographs of the wrist frequently miss hamate fractures. Oblique and carpal tunnel views can be obtained when a fracture of the hamate is suspected. Advanced imaging with high-resolution computed tomography should also be considered if radiographs are negative and high suspicion for fracture remains or for the purpose of pre-operative planning. Co-existing injuries often include subluxation or dislocation of the 4th and 5th metacarpals with or without fracture. Non-displaced injuries that are stable may be treated non-operatively with immobilization. Displaced or unstable fracture patterns typically require closed reduction and percutaneous pinning versus open reduction internal fixation in order to restore anatomical alignment and maximize outcomes. Hamate body fractures are uncommon fractures of the carpus. When appropriately treated, patients with hamate body fractures usually recover full pain-free range of motion and preserved grip strength. Complications are usually secondary to late presentation or noncompliance.