Metacarpal Fractures

Joseph A. Rosenbaum

Hisham M. Awan

INTRODUCTION

Pathoanatomy
- Fractures of the bones of the hand typically secondary to trauma
- Force applied to the affected bone exceeds its strength.
Mechanism of injury
- Mechanisms of injury include crush, torsional, angular, axial load, traction.
- High-energy mechanisms typically cause comminution.
- Fracture may be part of a more severe overall injury pattern including soft tissue injury to ligament, joint capsule, tendon, nerve, and/or vessels.
- Multiple metacarpals may be involved.
Epidemiology
- Fractures of phalanges and metacarpals are among the most common fractures.
- Account for approximately 10% of all fractures
- Common in laborers and athletes
- Males are affected more than females.
- Younger patients are affected more than older patients.

EVALUATION

History
- Typically caused by trauma, either direct or indirect
- Rarely can be pathologic fractures with minimal or no antecedent trauma
- Presentation may be delayed.
- Often overlooked initially in polytrauma cases
Physical examination
- Assess for edema, angular deformity, rotational deformity, and quality of soft tissues.
  - Rotational deformity assessment—patient makes a fist, and all fingers should cascade equally and point toward the volar scaphoid tubercle (Figures 11.1 and 11.2).
  - If patient is unable to flex digits to examine for rotational deformity, examine the nail plates in full extension to see if they are all parallel.
- Assess sensation and capillary refill distally.
- Assess the other digits as well as the hand and wrist.
- Test for tendon function individually for each finger (flexor digitorum superficialis, flexor digitorum profundus, extensor digitorum communis).
Imaging and classification
- Obtain hand radiograph initially if metacarpal fracture is suspected (posteroanterior, lateral, oblique).
- Brewerton views (MP flexed 65° with dorsum of fingers lying on plate and tube angled 15° ulnar-to-radial) to assess metacarpal heads
- Open versus closed
- Intra-articular versus extra-articular
- Stable versus unstable fracture pattern
  - Comminuted versus simple (Simple are generally more stable.)
  - Transverse versus oblique (transverse more length-stable)
- Angulation (transverse shaft fractures tend to angulate apex dorsal)
- Translation
- Presence or absence of foreign bodies
Anatomic classification
- Metacarpal head fractures
- Neck fractures
  - Common, especially in ring and small finger (“boxer’s fracture”)
- Shaft fractures
  - Common
- Base fractures
- Thumb extra-articular base fractures

FIGURE 11.1 Digital rotation is assessed with the fingers flexed to 90° at the metacarpophalangeal (MP) and proximal interphalangeal joints, with the distal interphalangeal joints extended. The fingers should all point to the scaphoid tubercle. In this image, the long finger is malrotated, pointing ulnar to the scaphoid.