Master Orthopaedics & Rheumatology
for PLAB 1

What the PLAB 1 Tests in Orthopaedics & Rheumatology

PLAB 1 Orthopaedics & Rheumatology tests the ability to recognise common musculoskeletal presentations and initiate appropriate management in a UK primary/secondary care setting. Candidates must differentiate between inflammatory arthritis (e.g., rheumatoid, psoriatic), crystal arthropathies (gout, pseudogout), septic arthritis (a surgical emergency), osteoarthritis, and common fractures (e.g., neck of femur, Colles', scaphoid). Knowledge of urgency: acute monoarthritis requires urgent aspiration and Gram stain/culture; suspected cauda equina syndrome mandates same-day MRI. You must know first-line disease-modifying drugs (methotrexate for RA), DAS-28 cut-offs, Ottawa ankle/knee rules, and when to refer for joint injection or arthroplasty. Questions often present a clinical vignette with X-ray findings, blood results (urate, CRP, rheumatoid factor, anti-CCP), or joint examination signs (swelling, warmth, reduced range).

High-Yield Concepts

• Septic Arthritis – Emergency Management: Acute monoarthritis with fever, inability to weight-bear, and CRP >100 mg/L. Perform urgent arthrocentesis before antibiotics. Gram stain, culture, crystal analysis. Empiric IV flucloxacillin 2 g QDS (or vancomycin if MRSA risk) plus gentamicin. Do not delay antibiotics if unable to aspirate immediately. Orthopaedic referral for surgical washout.
• Gout – Diagnosis and First-Line Treatment: Podagra (first MTP) or acute monoarthritis with elevated urate >360 µmol/L. Confirm by polarized microscopy: negatively birefringent crystals. Acute attack: NSAID (naproxen 500 mg BD) or colchicine 500 µg BD (max 1 mg/day) if contraindicated. Long-term urate-lowering: allopurinol 100 mg daily, titrated to target urate <300 µmol/L. Do not start allopurinol during acute attack.
• Rheumatoid Arthritis – Diagnosis and DMARD Initiation: Symmetrical small joint synovitis >6 weeks, morning stiffness >30 min, positive rheumatoid factor or anti-CCP, erosions on X-ray. DAS-28 score >3.2 indicates moderate activity. First-line DMARD: methotrexate 7.5–25 mg weekly with folic acid 5 mg weekly (not on same day). Escalate if inadequate response at 3 months. NICE recommends adding a TNF inhibitor (e.g., adalimumab) if DAS-28 >5.1 despite two DMARDs.
• Neck of Femur Fracture – Diagnosis and Management: Elderly patient after fall, shortened externally rotated leg, unable to weight-bear. X-ray AP pelvis and lateral hip. Urgent orthopaedic referral; surgery within 48 hours (NICE CG124). Pre-op: analgesia, IV fluids, pressure area care, DVT prophylaxis (LMWH). For intracapsular displaced fracture in fit patient: hemiarthroplasty or total hip replacement. For extracapsular: dynamic hip screw or intramedullary nail.
• Cauda Equina Syndrome – Red Flag: Bilateral sciatica, saddle anaesthesia, urinary retention (post-void residual >200 mL), faecal incontinence, loss of anal tone. Suspect with acute low back pain and any of these. Emergency MRI whole spine (within 24 hours) and neurosurgical referral. Do not perform lumbar puncture. Corticosteroids not recommended.
• Ottawa Ankle Rules – When to X-Ray: Ankle X-ray only if pain near malleoli AND inability to weight-bear 4 steps immediately AND one of: bone tenderness at posterior tip or base of lateral malleolus (distal 6 cm), or posterior tip or base of medial malleolus. Foot X-ray if tenderness at navicular or base of 5th metatarsal. Sensitivity >98% for clinically significant fractures.
• Ankylosing Spondylitis – Key Features and Management: Chronic low back pain <40 years, improves with exercise, worse at rest, morning stiffness >30 min. Sacroiliitis on MRI. HLA-B27 positive in 90%. First-line: NSAIDs (naproxen) and physiotherapy. If inadequate response: TNF inhibitor (adalimumab, etanercept). Measure BASDAI score. Monitor for uveitis and restrictive lung disease.
• Polymyalgia Rheumatica – Diagnosis and Treatment: Age >50, bilateral shoulder and hip girdle pain/stiffness, morning stiffness >45 min, raised ESR/CRP (often >100 mm/h), normal CK and RF. Rapid response to prednisolone 15 mg daily (dramatic improvement within 3 days). Maintain for 4 weeks then taper. Exclude giant cell arteritis (temporal headache, jaw claudication, vision loss) – if present, start prednisolone 40–60 mg daily.

Common Traps in Orthopaedics & Rheumatology Questions

• Assuming gout always has elevated urate during acute attack – urate can be normal; diagnosis is by crystal identification, not blood level alone.
• Using the Ottawa ankle rules for children under 5 years or patients with altered sensation – they are validated only for adults with isolated ankle injury.
• Ordering an MRI for suspected cauda equina without first checking post-void residual volume – a normal scan does not rule out if residual >200 mL.
• Prescribing allopurinol for acute gout – this can worsen the attack; start only after inflammation has fully resolved (usually 2 weeks).
• Mistaking pseudogout for gout – pseudogout shows positively birefringent rhomboid crystals (calcium pyrophosphate) and often affects the knee; treat with joint aspiration and NSAIDs, not allopurinol.
• Forgetting to check temporal artery biopsy and start high-dose steroids in suspected giant cell arteritis – delay can cause permanent vision loss.

How to Revise Orthopaedics & Rheumatology for the PLAB 1

Focus on acute monoarthritis (septic vs crystal vs inflammatory) and red flags in back pain (cauda equina, fracture, malignancy). Questions often give lab results (CRP, urate, RF, anti-CCP) and ask for next step – be ready to choose aspiration, X-ray, or urgent referral. Memorise Ottawa rules precisely; they appear frequently. Practise interpreting DAS-28 cut-offs (remission <2.6, low <3.2, moderate 3.2–5.1, high >5.1) and NICE guidelines for RA and fracture timing. Do not over-investigate simple mechanical back pain; know when to suspect inflammatory back pain (age <40, morning stiffness, response to NSAIDs). Review X-ray descriptions: joint space narrowing, osteophytes (OA), erosions (RA), chondrocalcinosis (pseudogout).

Practise it: MedLumen has 50 Orthopaedics & Rheumatology questions for the PLAB 1, each with a full explanation and references.