A nondisplaced shaft fracture of the right fifth metacarpal has a physician's order for full-time splinting. Which orthosis would the COTA most likely fabricate?

• A. Dorsal hood splint with the wrist in approximately 20° flexion, all MCP joints in 70°-90° flexion, and IP joints in 0° extension
• B. Volar-based ulnar gutter with MCP and IP joints of the ring and fifth fingers in 0° extension and the wrist in neutral
• C. Dorsal-based wrist cockup splint with MCP and IP joints free and the wrist in approximately 20° extension
• D. Volar-based ulnar gutter with MCP joints of the ring and fifth fingers in 70°-90° flexion, fourth and fifth IP joints in 0° extension, and the wrist in approximately 20° extension

Answer: (D)

For a nondisplaced shaft fracture of the fifth metacarpal, stable immobilization of the involved digits is essential to maintain alignment during healing. The best approach is a volar-based ulnar gutter splint that specifically immobilizes the ring and little fingers, keeping the MCP joints in strong flexion (about 70–90 degrees) while the IP joints stay in extension. This position relaxes the long flexor tendons and prevents bending that could shift the fracture, and the slight wrist extension (around 20 degrees) reduces extensor tendon tension and helps maintain splint stability.

A dorsal hood splint would not provide optimal control of the ulnar-sided digits and often alters wrist positioning in a way not ideal for a shaft fracture. A volar gutter with joints in extension would not adequately immobilize the MCP joints, increasing the risk of displacement. A wrist cockup splint that leaves the MCP and IP joints free would fail to immobilize the fracture itself. Therefore, the volar-based ulnar gutter with the described finger and wrist positions best meets the need for full-time immobilization and fracture stability.