What is the most likely diagnosis and recommended treatment plan for a patient with tenderness and swelling of the second finger distal interphalangeal joint, unknown mechanism of injury, and pain radiating to the wrist when picking up an object?

Likely Diagnosis and Treatment Plan

The most likely diagnosis is a distal interphalangeal (DIP) joint fracture with possible extensor tendon injury (mallet finger), and you should immediately obtain a 3-view radiographic examination of the hand to guide definitive management.

Diagnostic Approach

Initial Imaging - Mandatory First Step

Obtain 3-view radiographs of the hand immediately 1. This is the standard of care for any suspected hand trauma and will detect:

• Fractures of the distal phalanx - particularly intra-articular involvement
• Bony avulsion injuries - especially at the extensor tendon insertion (mallet injury)
• Joint subluxation or dislocation
• Fracture fragments requiring operative fixation

The 3-view examination should include posteroanterior (PA), lateral, and oblique projections. An internally rotated oblique view increases diagnostic yield for phalangeal fractures 1.

Key Clinical Features Suggesting Specific Diagnoses

The radiation of pain to the wrist with gripping is particularly concerning and suggests:

• Significant soft tissue injury extending proximally
• Possible flexor or extensor tendon involvement
• Inflammatory process affecting the entire digit

The unknown mechanism of injury raises suspicion for:

• Occult fracture (may not be visible on initial radiographs)
• Inflammatory arthropathy (though less likely with acute presentation)
• Calcific tendonitis (rare but possible) 2

Differential Diagnosis Priority

Most Likely: Fracture with Tendon Injury

Osseous mallet injury is high on the differential given DIP joint involvement 1. Look for:

• Bony avulsion at extensor mechanism insertion
• Involvement of >1/3 of articular surface (requires operative fixation)
• Palmar displacement of distal phalanx
• Interfragmentary gap >3mm (surgical indication) 1

Alternative: Occult Fracture

If initial radiographs are negative but clinical suspicion remains high, do not dismiss the injury 1. Options include:

• Short arm cast with repeat radiographs at 10-14 days (acceptable but delays diagnosis) 1
• CT without contrast - preferred for confirming occult fractures and evaluating intra-articular extension 1
• MRI without contrast - useful if soft tissue injury (ligaments, tendons, pulleys) is suspected, though not typically indicated for acute digital fractures 1

Less Likely but Consider: Inflammatory Arthropathy

Given the unknown mechanism, consider:

• Psoriatic arthritis - can present with isolated DIP involvement 3
• Gout - though typically more acute and dramatic
• Calcific tendonitis - rare in fingers but possible 2

However, these are less likely given the acute presentation with swelling and functional impairment.

Treatment Algorithm

If Radiographs Show Fracture:

Non-operative management:

• Fractures with <1/3 articular surface involvement
• No joint subluxation
• Interfragmentary gap <3mm
• Treatment: Splinting in slight DIP flexion for 6 weeks

Operative management indicated for:

• Bony avulsion involving >1/3 of articular surface
• Palmar displacement of distal phalanx
• Interfragmentary gap >3mm
• Joint instability 1, 4

If Radiographs Are Negative:

Immediate management:

• Buddy taping to adjacent finger
• NSAIDs for pain control (see pharmacologic section below)
• Ice and elevation
• Activity modification

Follow-up strategy:

• If symptoms persist beyond 7-10 days: obtain CT without contrast to exclude occult fracture 1
• If pain radiating to wrist persists: consider MRI without contrast to evaluate flexor/extensor tendons, collateral ligaments, and volar plate 1

Pharmacologic Management

Topical NSAIDs are first-line for pain control 5. They provide:

• Superior safety profile compared to oral agents
• Adequate pain relief for localized injury
• Minimal systemic side effects

Oral NSAIDs should be used for limited duration only if topical agents insufficient 5. Given the radiation of pain to the wrist, a short course (5-7 days) of oral NSAIDs may be appropriate initially.

Avoid:

• Intra-articular corticosteroid injections in DIP joints (not recommended for routine use) 5
• Prolonged oral NSAID use without gastroprotection

Critical Pitfalls to Avoid

1. Do not assume "no fracture" based on 2-view radiographs alone - 3 views are mandatory for finger injuries 1

2. Do not delay imaging - radiographs should be obtained at initial presentation, not after a trial of conservative management

3. Do not ignore the wrist pain - this suggests more extensive injury than isolated DIP pathology and may require broader imaging if symptoms persist

4. Do not miss mallet injuries - even small avulsion fractures can lead to permanent extensor lag if undertreated 1

5. Beware of prolonged symptoms - PIP joint sprains (and by extension DIP injuries) commonly cause swelling and dysfunction lasting months; 63% of patients have resolution within 1 year, but many continue to have functional limitations 6

Expected Outcomes and Counseling

Set realistic expectations:

• Even with appropriate treatment, finger swelling and stiffness may persist for 6-12 months 6
• Some degree of extensor lag is common after DIP injuries
• Grip strength may be reduced during healing
• Return to full normalcy occurs in only 42% of patients with finger joint injuries 6

Follow-up timing:

• Recheck at 7-10 days if symptoms not improving
• Repeat radiographs at 2 weeks if initial films negative but clinical suspicion high 1
• Consider hand surgery referral if operative criteria met or if no improvement after 2-3 weeks of conservative management