What are the possible diagnoses and recommended treatment for left distal forearm pain with swelling, warmth, and limited wrist and hand range of motion?

Acute Compartment Syndrome Must Be Ruled Out Immediately

This presentation of distal forearm pain with swelling, warmth, and limited range of motion to wrist and hand requires urgent evaluation for acute compartment syndrome—a limb-threatening emergency that demands immediate fasciotomy if confirmed.

Critical Initial Assessment

The combination of pain, swelling, and limited range of motion represents a surgical emergency until proven otherwise. You must immediately assess for:

• Pain out of proportion to examination findings (hallmark sign)
• Pain with passive stretch of fingers and wrist (most sensitive early finding)
• Progressive tightness of the forearm compartments on palpation
• Sensory changes in the hand (median, ulnar, or radial nerve distributions)
• Weakness of finger flexion/extension

If compartment syndrome is suspected clinically, measure compartment pressures immediately. Pressures >30 mmHg or within 30 mmHg of diastolic blood pressure mandate emergency fasciotomy 1, 2. Do not wait for loss of pulses—this is a late finding indicating irreversible damage 3.

Differential Diagnosis Framework

High-Risk Emergent Conditions (Rule Out First)

Acute Compartment Syndrome 1, 3, 2:

• Can occur even without direct forearm trauma
• May result from crush injury, thermal injury, or even sudden forceful supination 4, 2
• Bilateral presentation is rare but documented 3
• Requires fasciotomy within 6-8 hours to prevent permanent disability

Septic Arthritis or Soft Tissue Infection:

• Warmth and swelling suggest possible infection
• Requires urgent aspiration if joint involvement suspected
• MRI can identify abscess or osteomyelitis 5

Traumatic Causes (If History Present)

Distal Radius Fracture:

• Initial radiographs are usually appropriate for acute trauma 5
• If radiographs negative but clinical suspicion high, obtain MRI without contrast or CT without contrast in 10-14 days 5
• Operative indications include post-reduction radial shortening >3mm, dorsal tilt >10 degrees, or intra-articular step-off >2mm in patients under 65 6

Tendon or Ligament Injury:

• MRI without contrast or ultrasound are equivalent appropriate next steps after negative radiographs 5
• US allows real-time dynamic assessment and is readily available

Subacute/Chronic Inflammatory Conditions

Tuberculous Flexor Tenosynovitis 7:

• Presents with progressive swelling over months
• "Rice body" appearance on surgical exploration
• MRI shows soft tissue mass arising from flexor tendons
• Requires surgical excision plus 6 months anti-tuberculosis treatment

Immediate Management Algorithm

Step 1: Emergency Triage (First 15 Minutes)

1. Assess for compartment syndrome clinically

   • If positive: Measure compartment pressures stat
   • If pressures elevated: Emergency fasciotomy consultation
   • Do NOT delay for imaging if compartment syndrome suspected

2. Check for signs of infection

   • Fever, systemic symptoms, erythema tracking
   • If present: Blood cultures, empiric antibiotics, surgical consultation

Step 2: Imaging Protocol (If Not Emergent)

Initial imaging: Plain radiographs of forearm, wrist, and hand 5

• Two views minimum (AP and lateral)
• Look for fracture, dislocation, foreign body, soft tissue swelling

If radiographs negative or equivocal 5:

• MRI without IV contrast (preferred for soft tissue detail, tendon/ligament injury)
• Ultrasound (equivalent alternative, allows dynamic assessment, readily available)
• CT without contrast (if MRI contraindicated or bony detail needed)

Step 3: Definitive Treatment Based on Diagnosis

For Compartment Syndrome:

• Emergency fasciotomy of flexor and extensor compartments plus carpal tunnel 1, 3
• Post-fasciotomy wound management may require skin grafting or flaps 4
• Extensive hand physiotherapy required 1

For Fractures:

• Operative fixation if meets criteria (see above) 6
• Home exercise program versus supervised therapy shows inconsistent evidence—no routine benefit demonstrated 6

For Infectious Tenosynovitis:

• Surgical debridement plus culture-directed antibiotics
• Consider tuberculosis if chronic presentation with rice bodies 7

Critical Pitfalls to Avoid

1. Waiting for loss of pulses to diagnose compartment syndrome—this indicates irreversible muscle necrosis 3

2. Ordering MRI when compartment syndrome is suspected—this delays life-saving fasciotomy

3. Assuming bilateral presentation rules out compartment syndrome—spontaneous bilateral cases are documented 3

4. Missing compartment syndrome in absence of direct forearm trauma—can occur from sudden supination forces alone 2

5. Relying solely on compartment pressure measurements—clinical diagnosis takes precedence; if clinical suspicion is high, proceed to fasciotomy even with borderline pressures

Given the warmth, swelling, and limited range of motion in your patient, obtain plain radiographs immediately while maintaining high suspicion for compartment syndrome. If pain is severe or progressive, measure compartment pressures and consult orthopedic surgery emergently.