What type of orthopedic splint is preferred for a comminuted mid‑shaft fracture of the fourth metacarpal?

Hand-Based Functional Splint for Comminuted 4th Metacarpal Fracture

For a comminuted mid-shaft fracture of the fourth metacarpal, use a hand-based functional splint that immobilizes the fracture site while allowing motion at the metacarpophalangeal (MCP), interphalangeal (IP), and radiocarpal joints. 1, 2, 3

Splint Selection and Rationale

A hand-based functional splint is superior to traditional forearm-based splints for metacarpal fractures because it maintains fracture reduction while preventing the devastating complication of finger stiffness. 3, 4

Key Design Features:

• The splint must be padded and comfortably tight but not constrictive—you should be able to slip a finger underneath 1
• Immobilize only the 4th metacarpal fracture site itself 2, 3
• Critical: Allow full motion at all unaffected joints including MCP, IP, and wrist joints 1, 2, 3
• Can be fabricated from thermoplastic material for custom fit 3, 4

Why Hand-Based Over Forearm-Based:

Hand-based splints demonstrate superior outcomes compared to traditional ulnar gutter or forearm-based splints:

• Significantly better range of motion at 3 weeks (p=0.048) 4
• Faster return of grip strength—patients reach expected strength by 2 months versus delayed recovery with forearm splints 5
• Excellent maintenance of fracture reduction in 90% of cases (27/30 patients) 3
• Lower patient morbidity and earlier return to work—20 of 24 employed patients continued working without missing days 3

Immobilization Duration and Follow-Up

Timeline:

• Immobilize for 3-4 weeks total 1, 6
• Average splint duration is approximately 24 days 6, 3
• Obtain radiographic follow-up at 3 weeks to assess healing and alignment 1, 2, 6
• Final radiographic assessment when immobilization is discontinued 1, 6

Immediate Rehabilitation Protocol

Begin active finger motion exercises immediately for ALL unaffected joints—this is non-negotiable. 1, 6

Why Immediate Motion Matters:

• Active motion does not adversely affect adequately stabilized metacarpal fractures 1, 2, 6
• Finger stiffness is extremely difficult to treat after healing and may require multiple therapy visits or even surgical intervention 1
• Compression gloves with early mobilization show 28-degree better flexion compared to rigid splinting at 2 weeks (p=0.0036) 7

Post-Immobilization:

• Transition to aggressive finger and hand motion exercises when the splint is discontinued at 3-4 weeks 1

Critical Pitfalls to Avoid

Over-Immobilization Errors:

• Never immobilize unaffected fingers—this dramatically increases risk of hand stiffness and functional impairment 1
• Prolonged immobilization beyond 4 weeks increases joint stiffness requiring additional therapy without providing benefit 1
• Rigid forearm-based splinting when functional hand-based splinting would suffice leads to unnecessary stiffness and prolonged disability 1

Monitoring Failures:

• Inadequate radiographic follow-up may miss loss of reduction requiring intervention 1
• Immobilization-related complications occur in 14.7% of cases including skin irritation and muscle atrophy 6

When to Consider Surgical Referral Instead

Do not attempt conservative splinting if any of these criteria are present:

• Displacement >3mm 2, 6
• Dorsal tilt >10° 2, 6
• Significant intra-articular involvement 2, 6

For comminuted fractures specifically, ensure adequate stability before proceeding with splinting—oblique or highly unstable comminuted patterns may fail conservative treatment 8

Emergency Red Flags:

• If the fractured extremity appears blue, purple, or pale, activate emergency services immediately—this indicates poor perfusion and represents a limb-threatening injury 1