What is the recommended splint for a proximal phalanx fracture of the thumb?

Thumb Spica Splint in Intrinsic-Plus Position

For a proximal phalanx thumb fracture, immobilize with a thumb spica splint that maintains the thumb in an intrinsic-plus (balanced) position while allowing wrist motion, and continue rigid immobilization for 3-6 weeks. 1

Splint Specifications

• Use a thumb spica splint that incorporates the thumb metacarpophalangeal (MCP) joint while allowing full wrist flexion and extension 2
• Position the thumb in slight flexion at the MCP joint (approximately 30 degrees) to maintain the intrinsic-plus position 2, 3
• The splint should immobilize the MCP joint while allowing interphalangeal (IP) joint motion to prevent stiffness 1
• Fiberglass or thermoplastic materials are preferred for custom fabrication and optimal comfort 2, 4

Critical Management Steps

• Obtain 3-view radiographs (posteroanterior, lateral, and oblique) immediately to assess fracture displacement, articular involvement, and malrotation 1
• Apply rigid immobilization rather than removable splints for displaced fractures to maintain reduction 5
• Begin active IP joint motion exercises immediately while keeping the MCP joint splinted to prevent stiffness 6, 1

Surgical Referral Indications

Watch for these red flags that require immediate orthopedic consultation:

• Fracture displacement >3mm 1
• Articular surface involvement >1/3 1
• Interfragmentary gap >3mm 1
• Malrotation on clinical examination - have the patient actively flex all fingers into a fist and look for scissoring (thumb crossing over or under adjacent finger) 1

Follow-Up Protocol

• Obtain repeat radiographs at 10-14 days to ensure fracture position is maintained 1
• Continue radiographic monitoring at 3 weeks and at cessation of immobilization 1
• Total immobilization duration: 3-6 weeks for stable, minimally displaced fractures 1
• Instruct the patient to move the IP joint regularly through complete range of motion during the immobilization period 1

Common Pitfalls to Avoid

• Do not use removable splints for displaced fractures - rigid immobilization is essential to maintain reduction 5
• Avoid immobilizing the wrist in extension, as this limits functional capabilities and causes forearm muscle atrophy 2
• Do not rely on 2-view radiographs alone - inadequate for detecting all fracture characteristics 1, 7
• Advise the patient to re-evaluate immediately if unremitting pain develops during immobilization 6