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Metacarpal shaft fractures

Author
Josh Bloom, MD, MPH
Section Editor
Patrice Eiff, MD
Deputy Editor
Jonathan Grayzel, MD, FAAEM

INTRODUCTION

Metacarpal fractures are common. They account for up to 50 percent of all hand fractures [1,2]. Fractures of the metacarpal shaft are usually the result of direct or indirect trauma, but fatigue fractures can occur in athletes or as occupational injuries due to repetitive stress. The biomechanics, diagnosis, and treatment of stress fractures are presented separately. (See "Overview of stress fractures".)

This topic will review issues related to metacarpal shaft fractures. A general overview of metacarpal fractures and discussions of other common hand and wrist injuries are presented separately. (See "Overview of metacarpal fractures" and "Scaphoid fractures" and "Proximal phalanx fractures" and "Middle phalanx fractures" and "Distal phalanx fractures" and "Distal radius fractures in adults" and "Overview of carpal fractures" and "Evaluation of the adult with acute wrist pain".)

CLINICAL ANATOMY

The heads of the metacarpals are bulbous and "cam" shaped, thereby permitting adduction, abduction, flexion, extension and passive rotation of the fingers. The collateral ligaments join the metacarpal to the proximal phalanx and are taut in flexion, while having some laxity in extension (figure 1 and figure 2 and figure 3). The functional importance of this configuration is that the metacarpal phalangeal (MCP) joints should be immobilized in flexion to prevent shortening of the collateral ligaments and subsequent loss of motion.

FRACTURE PATTERNS AND MECHANISM OF INJURY

Metacarpal shaft fractures occur in three basic patterns: transverse, oblique, and comminuted.

Transverse fractures are caused by a direct blow. These fractures are typically pulled into apex dorsal angulation by the forces of the interosseous muscles (figure 4 and figure 5 and figure 6) and extrinsic flexor tendons exerted on the metacarpal shaft.

                 

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Literature review current through: Nov 2016. | This topic last updated: Mon Oct 10 00:00:00 GMT+00:00 2016.
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