What is the appropriate workup and management for left foot metatarsophalangeal joint pain?

Workup and Management of Left MTP Joint Pain

Initial Imaging Approach

Begin with weightbearing plain radiographs of the left foot (AP, lateral, and sesamoid axial views) as your first-line imaging study. 1 Radiographs effectively distinguish among different causes of MTP joint pain including hallux valgus, hallux rigidus, sesamoid pathology, osteoarthritis, stress fractures, and Freiberg's infraction. 1, 2

Key Radiographic Findings to Assess:

• Joint space narrowing and osteophyte formation suggest osteoarthritis or hallux rigidus 3, 4
• Sesamoid position and integrity to evaluate for dislocation, fracture versus bipartite sesamoid, or osteoarthritis 1
• Soft tissue swelling may be the only early finding in acute infections 5
• Joint effusion raises concern for septic arthritis or inflammatory arthropathy 5
• Erosions and periosteal reaction indicate osteomyelitis 5

Advanced Imaging When Radiographs Are Normal or Nondiagnostic

Proceed to MRI if radiographs show only soft tissue swelling or are completely normal, as MRI provides comprehensive evaluation of soft tissues, bone marrow, and occult pathology. 5 MRI has the highest sensitivity for detecting occult fractures, stress injuries, plantar plate tears, sesamoid pathology, and early osteomyelitis. 1

Alternative Advanced Imaging:

• Ultrasound is valuable for detecting joint effusions, plantar plate tears, tenosynovitis, and radiolucent foreign bodies 1
• CT with IV contrast helps differentiate cellulitis from abscess/myositis and evaluates cortical bone abnormalities 5

Diagnostic Workup Based on Clinical Presentation

If Infection Is Suspected (erythema, warmth, systemic symptoms):

• Perform image-guided aspiration for culture if septic arthritis or soft tissue abscess is suspected on imaging 5
• Culture is the reference standard for diagnosis, though negative cultures don't exclude infection if antibiotics were already started 5
• MRI has high sensitivity and specificity for osteomyelitis; a negative MRI excludes it 5

If Inflammatory Arthropathy Is Suspected:

• Consider gout, rheumatoid arthritis, or other inflammatory conditions 2, 6
• Laboratory workup including uric acid, inflammatory markers, and rheumatologic panel may be indicated 2

If Traumatic Injury Is Suspected:

• Weightbearing radiographs with comparison views of the contralateral foot are optimal for evaluating plantar plate disruption 1
• Fluoroscopy can assess sesamoid tracking with forced dorsiflexion 1

Initial Conservative Management

Start with topical NSAIDs as first-line pharmacological treatment due to superior safety profile compared to oral NSAIDs. 3, 7 Topical diclofenac gel shows meaningful improvements in pain and function after 8 weeks. 7

Additional Conservative Measures:

• Prescribe custom orthoses for prolonged use (minimum 3 months) to achieve symptom relief 3, 7
• Proper fitting is critical to prevent pressure sores 3
• Implement exercises to improve function and muscle strength while reducing pain 3
• Provide patient education on disease nature, self-management, ergonomic principles, and pacing of activity 3, 7

Second-Line Conservative Options:

• Oral NSAIDs for limited duration when topical therapy provides insufficient relief 3
• Intra-articular corticosteroid injection for painful joints when initial measures fail 3, 7
• Chondroitin sulfate may provide pain relief, though evidence quality varies 3

Surgical Intervention Criteria

Reserve surgery only for patients with structural abnormalities when conservative treatment has failed to adequately relieve pain. 3, 7

Surgical Options:

• Arthrodesis (fusion) is the gold standard for end-stage arthritis and severe deformity 7, 4
• Arthroplasty is specifically indicated for hallux ulcers in diabetic patients with limited MTP joint range of motion 3, 7
• Debridement of dorsal osteophytes relieves impingement in hallux rigidus with less advanced arthrosis 4

Common Pitfalls to Avoid

• Don't rely solely on radiographs for soft tissue pathology—they have poor sensitivity for plantar plate tears, Morton's neuroma, and early infections 1, 5
• Don't skip weightbearing views when evaluating MTP joint pathology, as they provide critical functional information 1
• Don't delay aspiration if infection is suspected—culture results guide definitive antibiotic therapy 5
• Don't prescribe orthoses for less than 3 months—shorter periods show no benefit 7