🦵 Mock Patient Script: Joint Pain – Standard

Practice your diagnostic reasoning with two contrasting cases of acute joint pain. Don’t let the swollen knee fool you—it’s not always gout or trauma.

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🚪 Doorway Information (Case 1)

• Age: 62
• Gender: Male
• Chief Complaint: “My knee suddenly became red and painful.”
• Vitals: T 38.2°C, BP 135/78, HR 95, RR 18, SpO₂ 97%

🔍 Click to open full case details

📋 Structured History

• Opening: “My knee hurts so much I can’t even walk.”
• Onset & Course: “It started suddenly this morning. I woke up and couldn’t move it.”
• Pain Description: “Sharp, constant. It feels hot and swollen.”
• Associated Symptoms: No trauma. I feel feverish, a bit chilled. No rash, no other joint pain.
• Medical History: Type 2 diabetes, Gout (not on meds), recent dental work
• Medications: Metformin, Irbesartan, occasional loxoprofen
• SH/FH: Social drinker, lives with wife, retired, no family hx of arthritis

🔍 Physical Examination

• Ill-appearing, febrile
• Right knee: hot, red, swollen, extremely tender. ROM ↓
• No rash, tophi, or trauma signs
• Other systems normal

🧠 Differential Diagnosis

1. Septic Arthritis – Most Likely
   ✅ Febrile, acutely hot swollen joint, risk factors (DM, dental)
   ❌ No systemic sepsis signs yet
2. Gout Flare
   ✅ Hx of gout, monoarthritis
   ❌ Not classic location, systemic features present
3. Reactive Arthritis
   ✅ Theoretically possible
   ❌ No evidence of recent GI/GU infection

🧾 SOAP Note

S: 62M with DM, acute hot painful knee, fever. No trauma. Hx of gout. Recent dental work.

O: T 38.2°C, HR 95. R knee red, warm, swollen. Labs pending.

A: R/O septic arthritis vs gout flare

P: Joint aspiration, gram stain/culture, blood cultures. Empiric IV abx. Hold NSAIDs until septic arthritis excluded.

🪞 Clinical Reflection – Case 1

Septic arthritis is a must-not-miss diagnosis. Prioritizing joint aspiration and rapid treatment can prevent irreversible joint damage. The presence of fever and DM raises suspicion despite prior gout history.

📎 Clinical Pearls – Case 1

• Septic arthritis is a true emergency.
• Risk factors include diabetes, dental work, and recent procedures.
• Never assume gout without synovial fluid analysis.

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🚪 Doorway Information (Case 2)

• Age: 80
• Gender: Female
• Chief Complaint: “My knee suddenly got swollen and painful.”
• Vitals: T 37.8°C, BP 148/76, HR 80, RR 18, SpO₂ 96%

🔍 Click to open full case details

📋 Structured History

• Opening: “I woke up and found my right knee was stiff and swollen.”
• Onset & Course: “It came on quite suddenly last night.”
• Pain Description: “Deep, achy pain. It feels hot and tight.”
• Associated Symptoms: No trauma. Mild warmth. No feverishness or rash.
• Past Episodes: “One similar event last year. Got better with rest.”
• Medical History: HTN, CKD, OA
• Medications: Furosemide, Amlodipine, Acetaminophen
• SH/FH: LTCF resident, no smoking, no gout history

🔍 Physical Examination

• Well-appearing, afebrile
• Right knee: red, swollen, warm, tender. ROM ↓
• No trauma, no tophi, no rash
• Other joints normal

🧠 Differential Diagnosis

1. Pseudogout – Most Likely
   ✅ Age, monoarthritis, diuretic use, prior similar episode
   ❌ No crystals yet
2. Septic Arthritis
   ✅ Warm swollen joint
   ❌ No systemic signs
3. Gout
   ✅ Possible
   ❌ Less likely: age, no prior gout

🧾 SOAP Note

S: 80F LTCF resident. Acute knee swelling. No trauma. On loop diuretic. Similar past episode.

O: T 37.8°C. R knee red, warm, swollen. ROM ↓

A: Suspected pseudogout. R/O septic arthritis.

P: Joint aspiration (crystals/culture), XR knee, colchicine. Monitor renal function.

🪞 Clinical Reflection – Case 2

Pseudogout is often missed in elderly women with OA. Chondrocalcinosis may provide clues. Diuretic use is a strong risk factor for calcium pyrophosphate deposition.

📎 Clinical Pearls – Case 2

• CPPD is common in elderly and those on diuretics.
• Joint aspiration is still necessary to exclude infection.
• X-ray may show chondrocalcinosis in affected joints.

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📚 References

1. Margaretten ME et al. “Does this adult patient have septic arthritis?” JAMA. 2007.
2. Zhang W. “EULAR recommendations for CPPD.” Ann Rheum Dis. 2011.
3. UpToDate: Acute monoarthritis – differential diagnosis and approach
4. ACR Guidelines 2020