In a 36‑year‑old female with 6‑day sudden severe medial ankle pain localized to the left medial malleolus radiating to the medial foot, limited inversion (<17°) without swelling or warmth, and a 1‑day dry cough with watery nasal discharge and throat itchiness triggered by dust, who has a history of gout (previous colchicine, now stopped) and osteoarthritis (uses celecoxib as needed), exposure to second‑hand smoke, and a dilation and curettage 2 months ago, with normal vital signs, what are the most likely diagnoses and immediate next steps?

Medial Ankle Pain with Limited Inversion: Likely Diagnoses and Immediate Next Steps

The most likely diagnosis is a deltoid ligament injury (sprain or partial tear), possibly with posteromedial impingement, and the immediate next step is to obtain plain radiographs of the ankle (AP, lateral, and mortise views) to rule out fracture, followed by consideration of MRI if symptoms persist beyond 6 weeks or if clinical suspicion for significant ligamentous injury remains high. 1

Primary Differential Diagnoses

1. Deltoid Ligament Injury (Most Likely)

• The sudden onset of severe medial malleolar pain radiating to the medial foot with limited inversion (<17°) strongly suggests deltoid ligament sprain or partial tear 2, 3
• Deltoid injuries can occur from pronation or supination-external rotation mechanisms and are often overlooked 2
• The absence of swelling or warmth does not exclude ligamentous injury, as these signs may be subtle or absent in partial tears 3
• Pain localized to the medial malleolus with restricted inversion is characteristic of deep deltoid fiber involvement 4, 2

2. Posteromedial Impingement Syndrome

• This occurs when deep posterior fibers of the deltoid ligament become crushed between the medial talus and medial malleolus, creating fibrotic scar tissue 4
• Clinically presents with persistent medial to posteromedial activity-related pain after injury, with deep soft tissue induration behind the medial malleolus 4
• Pain is reproduced by palpating the posteromedial area while moving the ankle into plantar flexion and inversion 4
• This diagnosis should be considered if symptoms persist beyond 6-8 weeks despite conservative management 1

3. Medial Malleolar Stress Fracture (Less Likely but Important)

• Although less common, stress fractures can occur in the medial malleolus from repetitive stress, particularly in patients with underlying ankle instability 5
• The patient's history of gout and osteoarthritis may predispose to altered biomechanics 5
• Initial plain radiographs are frequently normal because the medial malleolus consists mainly of cancellous bone 5
• This diagnosis requires high clinical suspicion and advanced imaging if plain films are negative 5

4. Acute Gout Flare (Less Likely Given Presentation)

• While the patient has a history of gout, the absence of swelling, warmth, and erythema makes acute gout less likely 1
• Gout typically presents with marked inflammation, warmth, and exquisite tenderness 1
• However, gout can occasionally present atypically, so this cannot be completely excluded without further workup

Immediate Next Steps: Diagnostic Algorithm

Step 1: Plain Radiographs (First-Line Imaging)

Obtain AP, lateral, and mortise views of the left ankle immediately 1

• Radiographs can identify fractures, stress fractures (if present for >2-3 weeks), osteoarthritis, or calcified loose bodies 1
• Mortise view is obtained by internally rotating the foot 15-20 degrees and is essential for evaluating the ankle mortise 1
• Look specifically for vertical fracture lines in the medial malleolus, periosteal reaction, or cortical erosion 5

Step 2: Laboratory Studies (If Infection or Gout Suspected)

• Check serum uric acid, ESR, and CRP if gout flare is being considered, though the lack of inflammation makes this less urgent 1
• These inflammatory markers are often elevated in gout but can be normal in up to 50% of cases 1

Step 3: Advanced Imaging (If Radiographs Normal and Symptoms Persist)

MRI without contrast is the next appropriate study if plain radiographs are normal and symptoms persist beyond 6 weeks 1

• MRI is highly accurate for evaluating ligament tears, tendon abnormalities, osteochondral lesions, and bone marrow edema 1
• MRI can identify deltoid ligament tears, posteromedial impingement lesions, and early stress fractures not visible on plain films 2, 5
• MRI should be obtained before 6 weeks if there is high clinical suspicion for significant ligamentous injury or if the patient is unable to bear weight 1

Step 4: Consider Stress Radiography (If Instability Suspected)

• Stress radiographs can assess ankle instability, though their accuracy has been questioned 1
• This is more relevant if there is concern for chronic lateral ankle instability contributing to medial-sided stress 5

Initial Management Recommendations

Conservative Treatment (First 6-8 Weeks)

Continue celecoxib 200 mg twice daily for anti-inflammatory effect and pain control 6

• Celecoxib has demonstrated efficacy in osteoarthritis and acute pain, with improvements apparent within 2 weeks 6
• The patient has already experienced partial relief (pain reduced from 8/10 to 4/10), suggesting some benefit 6

Implement RICE protocol (Rest, Ice, Compression, Elevation) 1

• Ice application should continue as the patient has already found this helpful 1
• Compression with an ankle brace or wrap can provide support 1

Consider short-term immobilization if pain is severe 1

• A walking boot or fixed-ankle walker-type device may be appropriate for 2-4 weeks if pain limits function 1
• This is particularly important if stress fracture is suspected 5

Physical therapy referral after acute pain subsides 1

• Focus on ankle stabilization exercises, proprioceptive training, and gradual return to weight-bearing 1
• Address any underlying biomechanical issues related to osteoarthritis 1

Red Flags Requiring Urgent Evaluation

• Development of warmth, swelling, or erythema → consider septic arthritis or acute gout flare 7
• Inability to bear weight → consider fracture or severe ligamentous injury 1
• Progressive pain despite appropriate conservative management → consider surgical consultation 1
• Systemic symptoms (fever, chills) → consider infection 1, 7

Regarding the Respiratory Symptoms

Upper Respiratory Tract Infection (Likely Allergic Rhinitis)

The 1-day history of dry cough with watery nasal discharge, throat itchiness triggered by dust exposure, and relief with lukewarm water is most consistent with allergic rhinitis or environmental irritant exposure rather than infectious upper respiratory infection.

Management:

• Antihistamines (e.g., cetirizine 10 mg daily or loratadine 10 mg daily) for allergic symptoms
• Nasal saline irrigation to clear irritants
• Avoidance of dust exposure and consideration of air filtration at home given neighbor's smoking
• Symptomatic treatment with throat lozenges and warm fluids as already being used

This respiratory presentation does not require antibiotics and is unrelated to the ankle pathology.

Common Pitfalls to Avoid

1. Overlooking deltoid ligament injuries when lateral ankle injuries are more obvious 2
2. Assuming absence of swelling/warmth excludes significant pathology – ligamentous injuries can present without these signs 3
3. Relying solely on initial plain radiographs – stress fractures may not be visible for 2-3 weeks 5
4. Failing to consider posteromedial impingement in patients with persistent medial ankle pain after conservative treatment 4
5. Not addressing underlying ankle instability which can contribute to medial-sided stress and injury 5