What is the initial treatment for a patient with a possible avulsion fracture at the base of the fifth metacarpal?

Initial Treatment of Avulsion Fracture at Base of Fifth Metacarpal

Obtain immediate 3-view radiographs (PA, lateral, and oblique) before any treatment to differentiate between tendinous injury and bony avulsion, and to assess fracture size, displacement, and joint subluxation, as these findings will determine whether conservative or surgical management is required. 1

Immediate Radiographic Assessment

The oblique view is critical for detecting phalangeal and metacarpal fractures that may be missed on 2-view examination alone. 1 This initial imaging must be completed before proceeding with any definitive treatment, as delaying radiographs can lead to unreliable exclusion of fractures requiring surgery. 2

Key radiographic features to assess:

• Size of avulsion fragment (≥1/3 of articular surface is a surgical indication) 2
• Presence of palmar subluxation of the metacarpal base 2
• Interfragmentary gap >3mm 2
• Intra-articular displacement or step-off 3

Initial Conservative Management (If Non-Surgical Criteria Met)

For avulsion fractures that do NOT meet surgical criteria:

Apply rigid immobilization immediately using a splint or cast that includes the affected metacarpal and adjacent joints. 3 Rigid immobilization is preferred over removable splints for displaced fractures. 3

• Apply ice-water mixture for 10-20 minutes with a thin towel barrier to reduce swelling 2
• Avoid heat application 2
• Do not attempt manual reduction before proper splinting 2
• Splint the hand in the position found until definitive evaluation 2

Critical pitfall: Even brief removal of the splint can restart the healing timeline, so emphasize uninterrupted immobilization to the patient. 2

Surgical Indications Requiring Immediate Orthopedic Referral

Refer urgently for surgical intervention if any of the following are present:

• Avulsion fracture involving ≥1/3 of the articular surface 2
• Palmar subluxation of the metacarpal base 2
• Interfragmentary gap >3mm 2
• Irreducible subluxation 2
• Open injury 2
• Intra-articular displacement with >2mm step-off 4

Fractures of the base of the fifth metacarpal are inherently unstable, and inadequate reduction may result in pain, functional disability, and osteoarthritic changes. 5 Surgical options include closed reduction with percutaneous pinning or open reduction with internal fixation for comminuted fractures where closed restoration of the articular surface is unfeasible. 5

Follow-Up for Non-Surgical Cases

• Begin active finger motion exercises of the PIP and MCP joints immediately while keeping the affected joint splinted to prevent stiffness 2
• If clinical suspicion remains high despite negative initial radiographs, place in a short arm cast and repeat radiographs in 10-14 days 1
• Consider MRI without IV contrast to detect occult fractures if radiographs remain negative but clinical suspicion persists 1
• Advise the patient to re-evaluate immediately if unremitting pain develops during immobilization 2

Evidence Quality Note

The available evidence for fifth metacarpal base fractures is limited. A Cochrane review found no single non-operative treatment regimen superior to another for fifth metacarpal neck fractures, though this was based on poor quality studies. 6 However, for base fractures with intra-articular involvement, surgical series demonstrate good functional outcomes with reduction and pinning. 5 The key is accurate initial radiographic assessment to identify surgical indications, as these fractures are inherently unstable and prone to poor outcomes if undertreated.