First Metatarsophalangeal Joint

Also written as 1st MTP, big toe joint, podagra joint.

The first metatarsophalangeal (MTP) joint is the most common site of acute gout (podagra) and can also be affected by infection, trauma, and osteoarthritis. Recognising the pattern of pain, swelling and systemic clues guides urgent and long‑term management, especially in low‑resource settings.

Definition and diagnosis

The first MTP joint is the articulation between the first metatarsal head and the proximal phalanx of the hallux. Acute inflammation is diagnosed clinically and confirmed by joint aspiration when possible.

• Joint aspiration and microscopy: Identifies crystals (urate or calcium pyrophosphate) or organisms; positive result confirms gout or septic arthritis
• Serum uric acid: Elevated (>7 mg/dL) supports gout but normal level does not exclude it
• Plain radiograph: Shows erosions with overhanging edges in chronic gout; may be unavailable, use clinical picture instead

• Red, hot, swollen joint with severe pain on passive dorsiflexion
• History of rapid onset (hours) favors crystal arthritis or septic arthritis

Severity and staging

Acute attacks are staged as mild (pain controlled with NSAIDs), moderate (requires colchicine or steroids), or severe (systemic signs, joint destruction, or septic risk).

• Mild: pain <5/10, no fever
• Moderate: pain ≥5/10, limited mobility, may need oral steroids
• Severe: fever, systemic toxicity, or suspected infection

Causes, most likely first

In East African hospitals the hierarchy of causes is:

• Gout (uric acid crystal deposition)
• Septic arthritis (often Staphylococcus aureus, Gram‑negative bacilli)
• Traumatic sprain or fracture of the metatarsal head
• Calcium pyrophosphate deposition disease (CPPD)
• Osteoarthritis (degenerative change in older patients)

How it presents

Patients describe sudden, excruciating pain in the big toe, often after a heavy meal or alcohol intake. The joint becomes erythematous, warm, and swollen; the patient may be unable to bear weight.

• Peak pain within 24 h, then gradual decline over 5‑7 days
• Tenderness over the metatarsal head, pain on passive dorsiflexion
• Systemic fever suggests infection rather than gout

Investigations

Prioritise bedside tools; send aspirate if possible. When labs are unavailable, rely on clinical patterns.

• Joint aspiration: Confirms crystal type or infection; if unavailable, treat empirically based on likelihood
• CBC with differential: Leukocytosis with left shift suggests septic arthritis
• Serum uric acid: Elevated level supports gout but normal does not rule it out

• Aspiration: definitive when crystals or pus seen
• Uric acid: supportive, not definitive
• CBC: leukocytosis (>12 ×10⁹/L) points to infection

Red flags and complications

Prompt recognition prevents irreversible joint damage and systemic spread.

• Fever >38 °C, chills, or rigors
• Rapidly enlarging swelling, skin breakdown
• Septic arthritis leading to osteomyelitis
• Tophi formation with chronic gout

Management

Treat the underlying cause first, then control pain and inflammation. Choose drugs that are available and safe in low‑resource settings.

• Gout: NSAID (e.g., ibuprofen) if no renal contraindication; colchicine if NSAID contraindicated; steroids (oral or intra‑articular) for refractory cases
• Septic arthritis: Empiric IV ceftriaxone plus gentamicin (adjust for local resistance); surgical drainage if pus present
• Trauma: Immobilisation, analgesia, and referral for fracture if suspected

Follow‑up and prevention

Arrange review within 3‑5 days to assess response. Long‑term gout prevention includes lifestyle change and urate‑lowering therapy when available.

• Educate on low‑purine diet, hydration, and alcohol moderation
• Screen for comorbidities (hypertension, renal disease, diabetes)
• Consider allopurinol or febuxostat when chronic hyperuricaemia persists

Often confused with

Several conditions mimic acute podagra.

• Septic arthritis – distinguished by fever, leukocytosis, and purulent aspirate
• Cellulitis of the toe – involves skin without joint effusion
• Hallux rigidus (osteoarthritis) – gradual onset, limited dorsiflexion without acute redness

Where results can mislead

Certain tests may be falsely reassuring.

• Normal serum uric acid during an acute gout attack
• Negative Gram stain if antibiotics were given before aspiration

Questions an examiner may ask

• A 48‑year‑old farmer presents with 2‑day sudden pain in the right first MTP joint, no fever. What is your next diagnostic step and why? — Perform joint aspiration to look for urate crystals; if unavailable, start NSAID therapy and arrange follow‑up.
• A patient with known gout develops fever and worsening swelling of the first MTP joint. How does this change your management? — Treat as possible septic arthritis: obtain aspirate, start empiric IV antibiotics, and consider surgical drainage.
• Explain why serum uric acid alone cannot rule out gout in an acute attack. — Levels may be normal during attacks; crystal analysis is definitive.
• What are the key features that differentiate septic arthritis from gout clinically? — Fever, systemic toxicity, leukocytosis, purulent aspirate versus rapid onset pain with erythema but no systemic signs.
• List three lifestyle measures that reduce future gout attacks and the physiological rationale. — Reduce purine intake (less uric acid production), increase water intake (enhances renal excretion), limit alcohol (decreases uric acid clearance).
• A patient cannot take NSAIDs due to renal disease. Which alternative acute gout treatment is preferred and why? — Colchicine is preferred because it does not affect renal prostaglandins; steroids are second line if colchicine contraindicated.
• Describe the radiographic changes seen in chronic gout of the first MTP joint. — Erosions with overhanging edges and soft‑tissue tophi; may be absent early.
• What red‑flag symptom would prompt immediate surgical referral for the first MTP joint? — Rapidly enlarging, fluctuant swelling with skin breakdown suggesting septic arthritis or osteomyelitis.

When to seek help

• Fever >38 °C with joint swelling
• Rapidly progressive pain despite analgesia
• Signs of systemic toxicity (confusion, hypotension)
• Visible skin ulceration or pus drainage

Quick questions

Can gout present with a normal uric acid level?

Yes; uric acid may be normal during an acute attack, so diagnosis relies on crystal identification.

When should I suspect septic arthritis instead of gout?

If the patient has fever, leukocytosis, or a history of skin infection, treat as septic until proven otherwise.

Is colchicine safe in patients with renal impairment?

Colchicine can accumulate; use reduced dose or choose steroids if renal function is poor.