Mastering Septic Arthritis Guidelines for PLAB 2 OSCE Success

Introduction

Septic arthritis is one of the most critical emergencies in orthopaedics and a high-yield topic for PLAB 2 OSCE. As an international medical graduate preparing for the PLAB 2 exam, understanding the systematic approach to suspected septic arthritis is essential. This comprehensive guide covers the latest NICE guidelines and clinical recommendations you need to know for exam success.

What is Septic Arthritis?

Septic arthritis is a serious bacterial infection of a joint space that requires urgent assessment and treatment. It can lead to rapid joint destruction and systemic sepsis if not treated promptly. The most commonly affected joints include the knee (50% of cases), hip, shoulder, elbow, and wrist.

Risk Factors

Understanding the risk factors is crucial for identifying high-risk patients in your PLAB 2 OSCE:

• Prosthetic joints - previous arthroplasty

• Rheumatoid arthritis - patients on immunosuppression

• Diabetes mellitus - poor glycemic control

• Alcohol excess - increased susceptibility

• Intravenous drug use - hematogenous spread

• Recent joint injection - direct inoculation

• Age extremes - very young and elderly

• Skin infections - nearby source of bacteremia

Clinical Presentation

Patients typically present with:

• Monoarticular arthritis - single joint involvement (most common)

• Severe pain - pain out of proportion to examination

• Restricted movement - marked limitation due to pain

• Systemic symptoms - fever, chills, malaise

• Joint swelling - warmth, erythema, effusion

The classic presentation is a hot, swollen, painful joint with limited movement – remember this triad for your OSCE!

Assessment and Investigation

History Taking (PLAB 2 OSCE Tips)

In your OSCE station, elicit:

• Onset and progression of joint symptoms

• Associated fever or systemic symptoms

• Previous joint problems or prostheses

• Recent infections or dental procedures

• Medication history including immunosuppressants

• Comorbidities (diabetes, rheumatoid arthritis)

• Social history (IV drug use, alcohol)

Examination Findings

Demonstrate systematic joint examination:

• Inspection - swelling, erythema, deformity

• Palpation - warmth, tenderness, effusion

• Movement - active and passive range of motion

• Neurovascular status - ensure distal circulation intact

Investigations

Urgent investigations include:

1. Blood tests

   • Full blood count (elevated WBC)

   • C-reactive protein (markedly elevated)

   • ESR (usually very high)

   • Blood cultures (before antibiotics)

   • Urea and electrolytes (renal function)

2. Imaging

   • X-ray (rule out other causes, may show soft tissue swelling)

   • Ultrasound (detects effusion, guides aspiration)

   • MRI (highly sensitive for osteomyelitis)

3. Joint Aspiration

   • Gram stain - immediate organism identification

   • Culture and sensitivity - definitive diagnosis

   • Cell count - >50,000 WBC/mm³ suggests infection

   • Crystal microscopy - rule out gout/pseudogout

Management Guidelines

Immediate Management (Within Hours)

Following NICE guidelines and current best practice:

1. Analgesia - adequate pain relief

2. Immobilization - comfortable position, avoid movement

3. Empirical antibiotics - start ASAP after cultures

4. Urgent orthopaedic referral - for joint washout

5. Monitoring - vital signs, inflammatory markers

Antibiotic Treatment

Empirical antibiotic regimen (adjust based on Gram stain):

Duration: Typically 4-6 weeks IV antibiotics, followed by oral antibiotics based on sensitivities and clinical response.

Surgical Management

• Arthroscopic washout - preferred for knee, shoulder, elbow

• Open washout - for hip or complex joints

• Repeated washout - may be needed for poor response

• Drainage - continuous irrigation systems

Discharge Criteria and Follow-up

For PLAB 2 OSCE, understand the criteria for safe discharge:

• Afebrile for 48+ hours

• Improving clinical symptoms

• Normalizing inflammatory markers

• Tolerating oral antibiotics

• Adequate pain control

• Follow-up arranged with orthopaedics

• Patient education on warning signs

Red Flags and Complications

Be prepared to identify complications:

• Osteomyelitis - chronic bone infection

• Joint destruction - irreversible damage

• Sepsis - systemic infection

• Permanent disability - loss of joint function

• Prosthetic joint infection - requires specialized management

PLAB 2 OSCE Scenario Tips

In your exam, you may face scenarios including:

• History station - taking focused history from a patient with hot, swollen knee

• Communication station - explaining diagnosis and need for urgent treatment to a patient

• Management station - outlining emergency management plan

• Prescribing station - writing appropriate empirical antibiotics

Key Communication Points

When explaining to patients, remember to:

• Use clear, simple language

• Explain the seriousness of the condition

• Describe the procedures (aspiration, surgery)

• Discuss antibiotic treatment duration

• Address concerns about mobility and recovery

• Provide written information if possible

Summary Checklist

For your PLAB 2 revision, memorize this checklist:

✅ Suspect in any hot, swollen, painful joint
✅ Check risk factors (prosthesis, RA, diabetes, IVDU)
✅ Urgent joint aspiration before antibiotics
✅ Start empirical antibiotics within 4 hours
✅ Refer to orthopaedics immediately for washout
✅ Monitor inflammatory markers for response
✅ Plan 4-6 weeks of antibiotic treatment

Conclusion

Septic arthritis remains a time-critical emergency requiring prompt recognition and treatment. For PLAB 2 success, master the systematic approach: identify red flags, perform focused assessment, arrange urgent investigations, initiate early antibiotics, and ensure urgent orthopaedic involvement. With thorough preparation using these guidelines, you'll be well-equipped to handle this high-stakes OSCE scenario.

Good luck with your PLAB 2 preparation!