Metacarpal Fractures

Metacarpal Fractures

🔷 Epidemiology & Mechanism

• พบ 30–40% ของ hand fractures
• สาเหตุหลัก: direct trauma, punching injury (5th metacarpal = “Boxer’s fracture”)
• อื่น ๆ: rotational force, axial load, crush injury, fatigue/stress fracture (athletes)

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🔷 Classification

จำแนกตามตำแหน่งของ metacarpal:

Location	Common Mechanism	Key Potential Complication
Head	Direct trauma	Intra-articular fracture, stiffness
Neck	Punch injury (5th digit)	Apex dorsal angulation
Shaft	Direct blow or twist	Rotation & malunion
Base	Axial load	CMC disruption or Bennett/Rolando pattern (if 1st MC)

Metacarpal 2–3: ค่อนข้าง fixed → deformity ส่งผลรุนแรงต่อ function
Metacarpal 4–5: more mobile → tolerate angulation เพิ่มเติมได้

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🔷 Clinical Examination Checklist

✅ Deformity – apex dorsal angulation common
✅ Malrotation – critical finding

• ตรวจโดยให้ผู้ป่วยกำมือ (MCP & PIP flexed 90°) → fingertips converge naturally
• หรือให้ MCP flex 90° + PIP/DIP extension → เล็บควรอยู่ระนาบเดียวกัน

🔴 Rotation = strong indication for surgical referral

✅ Skin integrity

• มี open wound? puncture? bite injury? → consider infected “fight bite”
  ✅ Neurovascular status
• 2-point discrimination, capillary refill

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🔷 Imaging

• Standard: PA, lateral, oblique views
• Key parameters to assess:
• Angulation (acceptable by digit)
• Shortening
• Rotation
• Articular involvement

Digit	Acceptable Angulation	Acceptable Shortening
2nd & 3rd (index, middle)	≤10°	≤2 mm
4th (ring)	≤20°	≤3–4 mm
5th (little)	≤30–40°	≤5 mm

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🔷 General Management Principles

🛠 Initial ED Management (All Patients)

• Immobilize: ulnar or radial gutter splint depending on digit
• Position: “Intrinsic-plus (safe position)”
• Wrist 20–30° extension
• MCP 70–90° flexion
• PIP, DIP in full extension
  → เพื่อลด intrinsic tendon tension & ป้องกัน contracture
• Ice, elevation
• Analgesics
• Early ROM of unaffected joints

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🔷 Indications for Immediate Orthopedic Consultation

🔴 Any of the following:

• Rotational deformity
• Open fracture / human bite (“fight bite”)
• Intra-articular fractures
• Significantly displaced or unstable fractures
• Multiple metacarpal fractures
• Neurovascular compromise
• Malalignment beyond acceptable limits
• First metacarpal base fractures (Bennett/Rolando)

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🔷 Definitive Treatment Summary

Fracture Type	Treatment
Nondisplaced, stable	Gutter splint → cast or functional brace
Angulated (within limits)	Closed reduction + splint
Unstable / rotational / intra-articular	ORIF or percutaneous pinning
Metacarpal neck (boxer)	Often closed reduction sufficient (unless rotation or excessive angulation)
Thumb metacarpal base	Often surgical

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🔷 Complications

🚩 Preventable with proper management:

• Malrotation → functional impairment
• Excessive angulation → grip weakness
• Joint stiffness (prolonged immobilization >4 weeks)
• Malunion / nonunion
• CMC arthritis (especially if articular involvement)

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🔷 Key Take-Home Clinical Pearls

• ✅ Rotation is NEVER acceptable → refer immediately
• ✅ Ulnar metacarpals (4–5) allow more angulation than radial (2–3)
• ✅ Intrinsic-plus splinting is essential for functional recovery
• ✅ Early motion improves outcome – avoid immobilization >4 weeks
• ✅ Fight bite over MCP = surgical emergency (risk septic arthritis, osteomyelitis)