Metacarpal Fractures

• Origin from shafts
• Flex MCP, Extend IPJ
• In fractures: Flex the distal fragment
• Result: Apex Dorsal Angulation (Head drops volar)

• Index (2nd): less than 10-15° (Rigid CMC)
• Middle (3rd): less than 10-15° (Rigid CMC)
• Ring (4th): less than 30-40° (Mobile CMC)
• Little (5th): less than 50-60° (Mobile CMC) - Boxer's

• Sensation (Digital nerves)
• Perfusion

• "Fight Bite": Laceration over MCP joint from tooth
• Assume infected human bite (Eikenella corrodens)
• Needs washout + antibiotics (Augmentin)

• Stable fractures
• Acceptable angulation
• No rotation

• Buddy Strapping: For stable shaft fractures
• Ulnar Gutter Splint: For 4th/5th Metacarpal
• Radial Gutter Splint: For 2nd/3rd Metacarpal
• Position of Safety (Not for fractures!): Intrinsic plus position usually used for immobilisation, BUT:
  • Some evidence suggests buddy taping alone allows earlier return to work for Boxer's fractures.

• 3-4 weeks immobilisation
• X-ray check at 1 week for position

• Rotational deformity (ANY)
• Unacceptable angulation (e.g., greater than 50° in 5th neck)
• Shortening greater than 5mm (relative)
• Open fractures
• Multiple metacarpal fractures
• Intra-articular displacement

1. K-wire Fixation:

   • Retrograde (intramedullary) or Transverse (pinning to adjacent bone)
   • Minimally invasive, wire removal later

2. ORIF (Plate/Screws):

   • For shaft fractures, unstable patterns
   • Anatomical reduction
   • Risk: Tendon adhesions, prominent hardware

3. Intramedullary Screw:

   • Newer technique for neck/shaft
   • Headless compression screw

• Metacarpal head fractures are uncommon (of the order of one in a hundred hand fractures), but they involve the small, highly congruent MCP joint, so they carry a real risk of stiffness, articular incongruity and post-traumatic arthritis, and — with comminution — avascular necrosis of the head.
• The index metacarpal head is the most frequently involved, and a laceration over the joint should raise the suspicion of a fight bite with cartilage penetration.
• The metacarpal head has a largely terminal, dorsally entering blood supply, which is why a comminuted head fragment can be devascularised.

epiphyseal fractures; collateral-ligament avulsion fractures; oblique (sagittal, unicondylar) fractures; vertical (coronal-plane) fractures; comminuted fractures; a boxer's neck fracture extending into the head; fractures with bone loss; and fractures associated with joint or soft-tissue loss. The scheme is descriptive rather than prognostic, but it maps directly onto treatment.

• Undisplaced: brief immobilisation followed by early protected motion to preserve the articular cartilage and prevent MCP stiffness.
• Displaced unicondylar (sagittal/coronal) split: open reduction and internal fixation with headless compression screws, mini-fragment screws, K-wires or bioabsorbable pins, aiming for anatomic joint restoration and a construct stable enough for early motion.
• Severely comminuted: internal fixation may be impossible; distraction external fixation using ligamentotaxis maintains joint space and allows motion, with osteochondral reconstruction or arthroplasty reserved for salvage.

• Each metacarpal is tethered to its neighbours proximally by the interosseous muscles and distally, at the level of the heads, by the deep transverse metacarpal (intermetacarpal) ligament, which links the volar plates of the index-to-little MCP joints.
• Intact adjacent metacarpals therefore act as internal splints, resisting shortening, angulation and rotation at a fracture in the ray between them. This is why an isolated central (middle or ring) metacarpal shaft fracture is one of the most stable fractures in the hand.

• When two or more adjacent metacarpals are fractured, the splinting buttress is lost on both sides, so the injury is inherently unstable and far more likely to shorten, angulate and rotate — hence the lower threshold for fixation and the place of "multiple fractures" on the operative list.
• The border rays (index and little finger) are held by the intermetacarpal ligament on only one side, so isolated second and fifth metacarpal fractures are less well splinted and more prone to displacement and malrotation than the well-protected central rays.