Metacarpal fractures

Metacarpal fractures are fractures of the metacarpal head, neck, base, or shaft; they are caused by direct or indirect trauma and account for approximately 30% of all hand fractures. Fracture of the 5th metacarpal neck (boxer's fracture) is most common and is usually caused by punching a solid object. Fractures of the metacarpal base are often fracture-dislocations affecting the carpometacarpal joints. Fractures of the metacarpal head are rare and usually the result of direct trauma or crush injury. Clinical features include general fracture signs, apex dorsal angulation, loss of knuckle contour, rotational deformity, and shortening. Diagnosis is confirmed on x-ray. Initial management includes closed reduction of angulated fractures and fracture immobilization with splint placement. Definitive management is determined by hand surgery or orthopedics and includes nonoperative management (e.g., with immobilization) or surgical management (e.g., with closed reduction and percutaneous pinning). Complications include permanent deformity, osteoarthritis, and reduced grip strength.

• Account for approx. 30% of all hand fractures ^[1]
• Most commonly involve the 5th metacarpal ^[2][3]

Epidemiological data refers to the US, unless otherwise specified.

• Direct or indirect trauma; (e.g., a fall, striking a firm object with a clenched fist, forced hyperextension or rotation of the joints) ^[4]
• Stress fractures (uncommon): due to repetitive strain (e.g., in tennis or badminton players) ^[5]

Metacarpal fractures are classified based on the location of the fracture (i.e., base, shaft, neck, head). (See also "Fracture classification.")

1st metacarpal fractures ^[4][6][7]

• 1st metacarpal base fractures (most common)
  • Bennett fracture
    • An intraarticular two-part fracture-dislocation at the base of the 1st metacarpal bone
    • The metacarpal shaft fragment is radially and proximally dislocated by the pull of the abductor pollicis longus muscle.
  • Rolando fracture
    • An intraarticular, comminuted fracture at the base of the 1st metacarpal bone
    • The fragments typically form a T- or Y-shaped pattern.
  • Winterstein fracture
    • An extra-articular fracture of the base of the 1st metacarpal bone
    • The distal fragment is adducted and flexed by the pull of the adductor pollicis and flexor pollicis brevis.
• 1st metacarpal shaft, neck, and head fractures

2nd–5th metacarpal fractures ^[4][7]

• Metacarpal base fractures
  • Typically intra-articular fracture-dislocations of the CMC joints
  • Reverse Bennett fracture
    • An intra-articular fracture-dislocation of the 5th metacarpal base
    • The metacarpal shaft fragment has ulnar and proximal displacement due to the pull of the extensor carpi ulnaris muscle.
• Metacarpal shaft fractures
• Metacarpal neck fractures (most common)
  • Typically affect the 4th and 5th metacarpals as a result of a closed fist forcibly coming into contact with a solid surface
  • Boxer's fracture: a transverse fracture of the 5th metacarpal neck
• Metacarpal head fractures (rare)

• Fracture signs include: ^[4][8]
  • Pain, swelling, and tenderness at the fracture site
  • Reduced range of motion at the carpometacarpal (CMC) and metacarpophalangeal (MCP) joints
• Deformity (visible/palpable) ^{[4] [1][8]}
  • Angulation (mostly apex dorsal angulation) → loss of the knuckle contour and/or pseudoclaw deformity ^[1]
  • Rotational deformity → digital overlap; more pronounced on flexion (abnormal finger cascade sign)
  • Adduction deformity in 1st metacarpal base fractures ^[9]
  • Shortening
  • Displacement
• Concomitant injuries
  • Neurovascular injuries
  • Signs of an open fracture
  • Other fractures (e.g., scaphoid, distal radius, distal ulna)

Clinical evaluation ^[7]

Any findings that suggest neurovascular injury or open fracture should prompt urgent orthopedic consultation.

• Neurovascular exam
  • Assess radial and ulnar artery pulses and capillary refill time.
  • Evaluate for median nerve injury, radial nerve injury, and ulnar nerve injury.
• Skin exam: Evaluate for laceration, tearing, and tenting.
• Rotation exam: Assess for finger cascade sign.

X-ray ^[1][4][7][9]

• Standard views: posteroanterior, oblique, and lateral x-rays of the hand
• Additional views
  • 1st metacarpal base views to assess for CMC joint involvement
    • True anteroposterior view (Robert view)
    • True lateral view (Bett view or Gedda view)
  • 2nd–5th metacarpal base views to assess for CMC joint involvement
    • Semipronated lateral view: for the 2nd–3rd CMC joints
    • Semisupinated lateral view: for the 4th–5th CMC joints
  • Metacarpal head fractures: Brewerton view ^[2]

In nonacute settings, CT hand may be considered for complex metacarpal fractures or diagnostic uncertainty. Concomitant tendon or ligament injury can be evaluated with ultrasound or MRI hand without IV contrast. ^[2][10]

Treatment of metacarpal fractures is similar in adults and children.

Initial management ^[7]

• Initiate general fracture care, including analgesia for fractures.
• Assess for indications to consult orthopedics for fractures, including fight bite injuries and rotational deformity.
• Perform bedside closed reduction for either of the following:
  • 1st metacarpal neck and shaft fractures with angulation < 30° ^[6]
  • 2nd–5th metacarpal neck and shaft fractures with significant angulation
• Perform postreduction x-rays and neurovascular examination.
• Immobilize all fractures with a splint.
  • 1st metacarpal fractures: thumb spica splint
  • 2nd and 3rd metacarpal fractures: radial gutter splint in the intrinsic plus position
  • 4th and 5th metacarpal fractures: ulnar gutter splint in the intrinsic plus position
• Arrange follow-up with hand surgery or orthopedics for definitive management.
  • 1st metacarpal fractures: urgent follow-up
  • 2nd–5th metacarpal fractures: within 1 week

2nd–5th metacarpal neck and shaft fractures with significant angulation ^[7]

There is a lack of consensus on what constitutes significant angulation of metacarpal fractures. Follow local guidelines and protocols. ^[7]

• Significant angulation in metacarpal neck fractures
  • > 10° in 2nd and 3rd metacarpals
  • > 35° in 4th metacarpal
  • > 45° in 5th metacarpal
• Significant angulation in metacarpal shaft fractures
  • > 10° in 2nd and 3rd metacarpals
  • > 20° in 4th and 5th metacarpals

Significant angulation can result in functional impairment (e.g., decreased grip strength, decreased MCP range of motion) if not adequately reduced. ^[1]

Definitive management ^[1][4][6][7]

All metacarpal fractures need to be evaluated by hand surgery or orthopedics to determine definitive management at follow-up.

Approach

• Remove the splint.
• Reassess the metacarpal fracture and angulation.
• Perform closed reduction for either of the following:
  • 1st metacarpal neck and shaft fractures with angulation < 30° ^[6]
  • 2nd–5th metacarpal neck and shaft fractures with significant angulation
• Perform postreduction x-rays and neurovascular examination.
• Determine nonoperative or surgical management based on fracture characteristics.

Nonoperative management ^[1][4][6][7]

• Indications
  • 1st metacarpal neck and shaft fractures with angulation < 30° ^[6]
  • 2nd–5th metacarpal neck and shaft fractures without significant angulation
  • Selected Bennett fractures with < 1–2 mm displacement
  • Selected metacarpal head fractures (e.g., nondisplaced, < 20% involvement of articular surface)
• Options
  • Splint
  • Cast
  • Buddy tape
  • Removable brace
• Duration: ≥ 4 weeks

Surgical management ^[1][4][6][7]

• Indications
  • 1st metacarpal neck and shaft fracture with significant displacement or angulation ≥ 30° ^[6]
  • 2nd–5th metacarpal neck and shaft fractures with significant angulation after closed reduction
  • Most metacarpal head and base fractures
  • Functional deformity (e.g., rotational deformity, pseudoclaw deformity, significant shortening)
  • Open fractures
• Options
  • Closed reduction and percutaneous pinning (e.g., with Kirschner wires)
  • Open reduction and internal fixation (e.g., with interfragmentary screws and/or plates, intramedullary nails)

• Malunion, nonunion
• Permanent deformity (e.g., malrotation, misalignment, shortening, pseudoclawing)
• Reduced grip strength
• Joint stiffness
• Osteoarthritis

We list the most important complications. The selection is not exhaustive.