Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

Featured on Channel NewsAsia

Metacarpal Fracture

Basics
Description
  • A fracture of the metacarpal bone, the small tubular bone in the hand
  • A 5th metacarpal neck fracture is called a boxer fracture.
  • Metacarpal fractures are classified according to their anatomic location (at the head, neck, shaft, or base).
  • Metacarpal fractures of the thumb are classified into 4 patterns (some eponymous), according to whether they are intra-articular or extra-articular and by the amount of comminution.
    • The Bennett fracture has a volar lip fragment of variable size at the CMC joint, and the remainder of the base is displaced from the joint.
    • The Rolando fracture is a Y-shaped intra-articular fracture.
Epidemiology
Most common in males 10-29 years old
 
Incidence
Hand fractures account for ~19% of all fractures, and the metacarpals are the 2nd most commonly broken bone in the hand (after the phalanges).
 
Prevalence
In children, metacarpal fractures account for ~10-40% of all hand injuries and are most common in those 13-16 years old.
 
Risk Factors
  • Sports injuries
  • Falls
  • Bicycle injuries
  • Maladaptive personality traits and anxiety symptoms
Etiology
  • Mechanisms of metacarpal fractures include direct trauma and crush injuries, but most occur from axial loading applied at the metacarpal head.
  • A common injury, the boxer fracture, is a fracture of the 5th metacarpal neck sustained while striking the 5th MCP joint of the clenched fist.
Diagnosis
Signs and Symptoms
  • The combination of history, physical examination, and radiographic views nearly always is diagnostic.
  • Pain and swelling mainly occur in the dorsum of the hand.
Physical Exam
  • Patients present with pain, swelling, and deformity at the location of the fracture.
  • Assess the shortening and malrotation of the affected digit by looking at the cascade of fingers when a fist is made.
  • Document the neurologic examination with 2-point discrimination and capillary refill.
  • Examine any break in the skin to ensure that the fracture is not open or that an intra-articular injury did not occur.
Tests
There are no laboratory tests to aid in the diagnosis.
 
Imaging
  • Obtain AP, lateral, and oblique plain radiographic views.
  • A true lateral view is necessary to measure fracture angulation.
  • Focused views on the involved metacarpal can give better detail of the fracture pattern.
Pathological Findings
  • Disruption of the bone cortex and periosteum
  • Hematoma formation
  • Later callus formation with eventual healing
Differential Diagnosis
  • Dislocation of the MCP joint
  • Extensor or flexor tendon injury
  • Contusion or soft-tissue trauma
Treatment
General Measures
  • Nonoperative treatment:
    • Most metacarpal fractures can be treated by splinting and casting.
    • An angulated fracture should be reduced and splinted.
    • The role of immobilization for 5th metacarpal fractures has been questioned.
      • 1 study has shown that an Ace wrap is sufficient treatment for displacement of <70°.
    • The hand should be splinted in the position of function, which is thought to lessen later stiffness.
      • Wrist in ~20° of dorsal angulation
      • MCP joints of both the affected and adjacent finger at 70-90° of flexion
      • The PIP and DIP joints in full extension
    • However, a recent study questioned the importance of the splint position and focused on keeping the length of time of immobilization to <5 weeks.
    • A recent meta-analysis showed no difference in outcomes among several methods of casting or splinting.
    • The patient should be instructed about the possibility of surgery if fracture reduction cannot be maintained with splinting.
    • Ice, elevation, and analgesics are important adjuncts in the initial treatment.
  • Operative treatment is indicated for:
    • Unstable, intra-articular, or multiple-digit fracture pattern.
      • Intra-articular fractures must be anatomically reduced.
    • Inability to obtain a satisfactory reduction
    • Malrotation of the digits
    • Open fractures:
      • Common in fight-bite injuries in which the MCP joint is penetrated by a tooth
      • Treated with operative irrigation, debridement, and pin fixation
  • Reasonable guidelines for permissible apex-dorsal angulation of the fractures are 10° for the index, 20° for the middle, 30° for the ring, and 40° for the small fingers.
    • Rotatory displacements in general are not acceptable and require additional treatment.
  • Most metacarpal fractures heal by 2 months.
Special Therapy
Physical Therapy
Gentle, active, and passive ROM motion exercises typically can be performed.
 
Surgery
  • Treatment of metacarpal fractures includes the use of pins, plates, screws, external fixators, and intramedullary pins.
    • Pins or Kirschner wires may be used in a longitudinal fashion to maintain length and rotation of fractures.
    • Mini-fragment plates may be used to repair fractures.
    • Kirschner wires also may be used as intramedullary PINS to maintain fracture reduction.
  • Fractures with substantial bone loss, such as from a gunshot wound, occasionally require an external fixator.
Follow-up
Prognosis
  • The prognosis is good to excellent when fractures are treated nonoperatively.
  • Kirschner wire and intramedullary pin fixation have been shown to have excellent results for metacarpal neck fractures.
  • Kirschner wire fixation gives excellent results for metacarpal shaft and base fractures.
  • Plate fixation may have more complications than nonoperative treatment or less invasive surgical techniques but may be necessary for comminuted fractures or those with bone loss.
  • Intra-articular fractures of the base of the thumb have good results when treated with Kirschner wires.
  • Comminuted intra-articular fractures have the worst prognosis, with subsequent joint pain and decreased function.
Complications
  • Soft-tissue damage results from the initial injury or is secondary to overzealous reduction attempts.
  • Flexor or extensor tendons may be damaged or develop decreased excursion.
  • Malunions with angulation and rotational deformity have the worst prognosis.
  • MCP stiffness is the result of immobilizing the joint in extension and allowing the collateral ligaments to shorten.
  • Surgical complications include infection, delayed wound healing, and sensory nerve injury.
  • Septic arthritis of the MCP joint may occur after fight bites or bites from dogs or cats.
Patient Monitoring
  • Obtain radiographs 1 week after closed or open reduction, and repeat in another 2-3 weeks.
  • Begin early ROM when appropriate.
Miscellaneous
Codes
ICD9-CM
  • 815.00 Closed metacarpal fracture
  • 815.10 Open metacarpal fracture
Patient Teaching
  • Intra-articular fractures have a higher incidence of stiffness and pain after healing.
  • Early ROM activities are begun when the fracture is stable.
FAQ
Q: How long does a metacarpal fracture take to heal?
A: Metacarpal fractures usually heal in ~2-3 months.
 
Q: Do metacarpal fractures require surgery?
A: Most metacarpal fractures are treated without surgery.

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