From the Guidelines
For fractures of the fourth and fifth metacarpal bones, an ulnar gutter splint is the recommended immobilization method. This recommendation is based on the principle of immobilizing the fracture site to allow proper healing, as suggested by the concept of simple immobilization for small, nonarticular, or minimally displaced fractures 1. When applying the ulnar gutter splint, it should be done with the wrist in slight extension (about 20-30 degrees), the metacarpophalangeal (MCP) joints flexed at 70-90 degrees, and the interphalangeal (IP) joints in slight flexion. Key considerations for the splint include:
- Extending from the distal forearm to the fingertips
- Covering the ulnar (little finger) side of the hand
- Leaving the thumb free to enable basic hand function
- Being well-padded to prevent pressure sores
- Secured with an elastic bandage, ensuring it is not too tight to avoid compromising circulation The immobilization period typically lasts for 3-4 weeks, followed by gradual mobilization and rehabilitation exercises to restore full hand function and prevent stiffness. The ulnar gutter splint is particularly effective for these fractures because it stabilizes the injured metacarpals, preventing rotation and angulation during healing, which could otherwise lead to malunion and subsequent functional impairment.
From the Research
Splint Options for Fourth and Fifth Metacarpal Bones Fractures
- For fractures of the fourth and fifth metacarpal bones, an ulnar gutter splint is a commonly used treatment option 2.
- The ulnar gutter splint is a simple and proven method for immobilizing boxer's fractures, which include isolated fractures of the distal fourth or fifth metacarpal bones 2.
- Another option is a functional metacarpal splint, which has been shown to be effective in treating fifth metacarpal neck fractures, with faster improvement in clinical scores and earlier gain of normal grip strength compared to ulnar gutter splint 3.
- However, it's worth noting that the ulnar gutter splint may cause iatrogenic rotation of the ring finger metacarpal fracture, and including the middle finger in the splint can help mitigate this issue 4.
Considerations for Splint Placement
- When placing a splint on a patient with fourth and fifth metacarpal bones fractures, it's essential to be aware of the anatomical course of the deep branch of the ulnar nerve, which is vulnerable to injury during hand surgery fixations 5.
- High caution should be taken during percutaneous pinning, and the use of radiological guidance, minimizing pining attempts, and limiting pin tip protrusion can help prevent nerve injury 5.