How to splint a 4th and 5th metacarpal fracture?

Splinting of 4th and 5th Metacarpal Fractures in the Emergency Department

For 4th and 5th metacarpal fractures, a functional hand-based splint that allows for metacarpophalangeal (MCP) joint, interphalangeal (IP) joint, and radiocarpal joint motion is the preferred method of immobilization in the emergency department, as it provides excellent maintenance of fracture reduction while allowing early functional recovery. 1

Initial Assessment and Splinting Technique

Assessment

• Evaluate for:
  • Fracture displacement (>5mm displacement requires surgical referral) 2
  • Intra-articular involvement
  • Rotational deformity (more clinically significant than volar angulation) 3
  • Ulnar angulation

Splinting Technique for 4th and 5th Metacarpal Fractures

1. Reduction if needed:

   • Perform closed reduction for significantly displaced or angulated fractures
   • Apply longitudinal traction followed by flexion of the MCP joint to 90° while applying pressure at the fracture site

2. Splint Application:

   • Hand-based functional splint:
     • Position the hand in the "safe position" (wrist in slight extension, MCP joints flexed at 70-90°)
     • Apply the splint along the ulnar border of the hand
     • Extend the splint from the distal interphalangeal (DIP) joint of the affected fingers to just proximal to the wrist
     • Ensure the splint immobilizes the fracture site while allowing motion of the MCP, IP, and radiocarpal joints 1

3. Securing the Splint:

   • Use elastic bandage to secure the splint
   • Avoid excessive pressure that could cause ulnar angulation or rotational deformity 3
   • Ensure proper padding at bony prominences

Evidence-Based Advantages

The American Academy of Orthopaedic Surgeons recommends rigid immobilization for displaced fractures, while removable splints are suitable for minimally displaced fractures 4, 2. However, recent evidence specifically for metacarpal fractures shows:

• Functional splinting provides faster functional recovery compared to traditional immobilization 5, 6
• Functional metacarpal splints allow patients to reach expected grip strength values earlier (by 2 months) compared to ulnar gutter splints 6
• Hand-based functional splints maintain fracture reduction while allowing continued joint motion, preventing stiffness 1
• 83% of patients with hand-based functional splints can continue working without missing days 1

Duration and Follow-up

• Average splint duration: 3-4 weeks (approximately 24 days) 1
• Begin active finger motion exercises immediately to prevent stiffness 2
• Apply ice during the first 3-5 days for symptomatic relief 2
• Radiographic follow-up at 3 weeks and at cessation of immobilization 2

Special Considerations

Cautions

• Monitor for:
  • Compartment syndrome (more common with circumferential casts)
  • Thermal injuries during cast application
  • Excessive immobilization risks: chronic pain, joint stiffness, muscle atrophy, and complex regional pain syndrome 2

Indications for Surgical Referral

• Displacement >5mm in any plane
• Intra-articular displacement
• Unstable fracture patterns
• Comminuted fractures where closed restoration of the articular surface is not possible 2

By using a functional hand-based splint for 4th and 5th metacarpal fractures, you can achieve excellent maintenance of fracture reduction while allowing for early return to function and minimizing patient morbidity.