What is the cause and treatment for sudden onset metatarsal pain and swelling without injury?

Sudden Metatarsal Pain and Swelling Without Trauma

The most likely diagnosis is acute gout affecting the metatarsophalangeal joints, and you should immediately initiate anti-inflammatory therapy while ruling out infection and stress fracture. 1

Immediate Diagnostic Priorities

Clinical Assessment

• Assess pain severity on a 0-10 scale: Pain ≥7 indicates severe acute arthritis requiring aggressive treatment 1
• Examine for signs of infection: Look for systemic inflammatory response, rapid progression, extensive erythema, warmth disproportionate to findings, or new wound anesthesia—these suggest limb-threatening infection requiring urgent surgical consultation 1
• Check for diabetes and neuropathy: Diabetic patients with sudden foot pain require special attention to rule out deep-space infection or Charcot neuroarthropathy 1

Differential Diagnosis Framework

Primary considerations for overnight onset without injury:

• Acute gout (most common): Sudden onset, severe pain, swelling, typically affects first metatarsophalangeal joint but can involve multiple metatarsals 1
• Stress fracture: Can present with acute pain despite gradual onset; second and third metatarsal heads most commonly affected 2, 3
• Infection: Particularly in diabetic patients or those with skin breakdown 1
• Acute vascular event: Sudden onset with cold extremity suggests arterial occlusion requiring urgent imaging 1

Imaging Algorithm

Initial Radiographs

• Obtain three standard views (AP, lateral, oblique) of the foot to rule out fracture, though stress fractures may not be visible for 2+ weeks 4, 2
• Weight-bearing radiographs provide critical stability information when patient can tolerate them 5
• Note: Ottawa rules do NOT apply here—they are designed for trauma scenarios and specifically exclude non-traumatic presentations 1

Advanced Imaging When Radiographs Are Negative

• MRI is the preferred next step for non-traumatic metatarsal pain with negative radiographs, as it detects stress fractures (bone marrow edema), soft tissue pathology, and early osteonecrosis 6, 7
• Bone scan shows early tracer accumulation in stress fractures before radiographic changes appear 3

Treatment Algorithm

For Suspected Acute Gout (Most Likely)

• Initiate anti-inflammatory therapy immediately if pain severity is moderate-to-severe (≥5/10) 1
• Treatment options based on severity:
  • Mild pain (≤4/10): NSAIDs or colchicine
  • Moderate-to-severe pain (≥5/10): Consider combination therapy or corticosteroids
  • Polyarticular involvement (multiple metatarsals): More aggressive therapy warranted 1

For Suspected Stress Fracture

• Immediate non-weight-bearing status with rest and ice to prevent displacement and nonunion 2
• Rigid immobilization preferred over removable splints for displaced fractures 5
• Orthopedic referral to guide definitive care 2

For Suspected Infection (Red Flags Present)

• Urgent surgical consultation if any limb-threatening signs present: systemic inflammatory response, rapid progression, pain out of proportion to findings, or extensive soft tissue involvement 1
• Do not delay surgical evaluation based on absence of fever or leukocytosis 1

Special Populations

Diabetic Patients

• Exclude Charcot neuroarthropathy when presenting with acute red, hot, swollen foot—requires thorough workup and early diagnosis to prevent deformities 1
• Assess for deep-space infection or abscess: Plantar wound with dorsal erythema suggests infection through fascial compartments requiring surgery 1
• Implement aggressive offloading to prevent complications in neuropathic patients 1

Patients with Vascular Risk Factors

• Check distal pulses immediately: Absent or diminished pulses with sudden pain suggest acute arterial occlusion 1
• Obtain CTA urgently if vascular compromise suspected—this is fast and reveals exact level of thrombosis 1
• Initiate anticoagulation immediately if acute limb ischemia diagnosed 1

Common Pitfalls to Avoid

• Do not assume absence of trauma history rules out stress fracture—these develop from repetitive microtrauma and can present acutely 2
• Do not rely solely on initial radiographs—stress fractures have 2+ week delay before becoming visible 2
• Do not dismiss pain in diabetic patients with neuropathy—they may have serious pathology with minimal symptoms 1
• Do not apply Ottawa rules to non-traumatic presentations—they specifically exclude scenarios >10 days after trauma or non-traumatic foot pain 1
• Do not assume absence of fever excludes infection—diabetic foot infections often lack systemic signs 1

Follow-Up Considerations

• If gout confirmed: Address urate-lowering therapy after acute attack resolves 1
• If stress fracture: Serial radiographs to confirm healing; early physical therapy with balance training after immobilization to prevent stiffness 4, 5
• If initial workup negative: Consider MRI to detect occult pathology including early stress fracture, osteonecrosis, or soft tissue inflammation 6, 7