INTRODUCTION

Metacarpal fractures account for 30 to 40 percent of all hand fractures. These fractures are usually the result of direct 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".)

Splinting is used in the initial immobilization of, and often is the definitive treatment for, metacarpal fractures. A detailed description of the techniques for applying splints is presented separately. (See "Splinting of musculoskeletal injuries".)

This topic will provide an overview of the classification and examination of metacarpal fractures as well as the anatomy of the metacarpal bones.

CLASSIFICATION

Metacarpal fractures are classified based upon their anatomic location. Fractures of the second, third, fourth, and fifth metacarpals are subdivided into those affecting the metacarpal head, neck, shaft, or base. Due to the unique biomechanics and anatomy of the thumb, fractures of the first metacarpal are classified separately.

Metacarpal fractures are further described by the degree of displacement, angulation, shortening, rotation, and by the fracture type (transverse, oblique, spiral, comminuted, impacted, or avulsion). The metacarpal neck and shaft are the most common sites for second through fifth metacarpal fractures, while the first metacarpal is usually fractured at the base.