Master Orthopedics
for DHA

What the DHA Tests in Orthopedics

The DHA Orthopedics exam tests the ability to manage common musculoskeletal presentations in the emergency department and outpatient clinics, with emphasis on fracture recognition, joint infections, and degenerative conditions. Candidates must demonstrate knowledge of the Ottawa Ankle and Knee Rules, the Gustilo-Anderson classification for open fractures, and the Garden classification for femoral neck fractures. Key decisions include when to aspirate a septic joint, which antibiotics to start empirically (e.g., flucloxacillin for native joint septic arthritis), and the indications for urgent surgical debridement. The exam also covers paediatric orthopedics, including SUFE (slipped upper femoral epiphysis) and developmental dysplasia of the hip (DDH), with specific screening protocols. Osteoporosis management using FRAX scores, bisphosphonates, and calcium/vitamin D supplementation is frequently tested. Candidates must be able to interpret X-rays for common fractures, dislocations, and signs of avascular necrosis.

High-Yield Concepts

• Ottawa Ankle Rules: Indications for ankle X-ray after acute injury: inability to bear weight immediately and in ED for 4 steps, plus bone tenderness at posterior edge or tip of either malleolus (medial or lateral). Sensitivity >98% for malleolar fractures.
• Gustilo-Anderson Classification for Open Fractures: Type I: clean wound <1 cm, minimal contamination. Type II: wound 1-10 cm, moderate contamination. Type IIIA: adequate soft tissue coverage despite extensive damage; IIIB: requires flap coverage; IIIC: vascular injury requiring repair. All open fractures need urgent IV antibiotics (e.g., co-amoxiclav or cefuroxime) and tetanus prophylaxis.
• Septic Arthritis Management: Empiric IV flucloxacillin 2g QDS (or cefuroxime 1.5g TDS) for native joints; consider clindamycin if penicillin-allergic. Aspiration before antibiotics if possible. Urgent orthopaedic referral for washout. Gram stain, culture, and crystal analysis are essential. CRP >100 and WCC >50,000 in joint fluid are suggestive.
• Femoral Neck Fracture: Garden Classification: Garden I: incomplete/valgus impacted; Garden II: complete non-displaced; Garden III: complete partially displaced; Garden IV: completely displaced. Displaced fractures (III/IV) have high risk of avascular necrosis and typically require hemiarthroplasty or total hip replacement. Non-displaced (I/II) may be treated with cannulated screws.
• Slipped Upper Femoral Epiphysis (SUFE): Presents in adolescents (10-16 years) with hip/groin pain, limp, and limited internal rotation. X-ray shows widened physis and 'blanch sign' of Klein. Stable slips: in situ pinning; unstable slips: urgent reduction and fixation. Bilateral involvement in 20-40%; consider prophylactic pinning.
• Developmental Dysplasia of the Hip (DDH) Screening: All newborns examined using Ortolani and Barlow tests. Ultrasound at 6 weeks if risk factors (breech, family history, female). Graf classification: Type I (normal), Type II (immature), Type III/IV (dislocated). Treatment: Pavlik harness for Graf II-IV up to 6 months; closed/open reduction if failed.
• Osteoporosis: FRAX and Treatment Threshold: FRAX tool calculates 10-year fracture risk. Treatment indicated if FRAX major osteoporotic fracture risk ≥20% or hip fracture risk ≥3% (UK guidelines) or T-score ≤ -2.5. First-line: oral alendronate 70mg weekly with calcium/vitamin D. Monitor with DXA every 1-2 years.
• Compartment Syndrome Diagnosis: Suspect in high-energy fractures (tibia, forearm) with pain out of proportion, paresthesia, pallor, pulselessness (late signs). Compartment pressure >30 mmHg or diastolic blood pressure minus compartment pressure <30 mmHg (ΔP <30) indicates fasciotomy. Do not wait for pulse loss.

Common Traps in Orthopedics Questions

• Confusing the Ottawa Ankle Rules with the Ottawa Knee Rules; knee rules require X-ray if age >55, isolated patellar tenderness, fibular head tenderness, inability to flex to 90°, or inability to bear weight.
• Forgetting that a normal X-ray does not rule out septic arthritis; MRI or ultrasound may be needed if clinical suspicion is high.
• Administering antibiotics before joint aspiration in suspected septic arthritis—this can sterilise the culture and delay definitive diagnosis.
• Using the term 'Garden I' for a non-displaced fracture but missing the valgus impaction that can be treated conservatively with non-weight-bearing.
• Assuming all paediatric limp is transient synovitis; always check for SUFE in adolescents and consider Perthes disease in younger children (4-8 years).
• Mistaking a posterior shoulder dislocation for anterior on X-ray; look for the 'light bulb sign' (humeral head internally rotated) rather than the classic anterior dislocation appearance.

How to Revise Orthopedics for the DHA

Prioritise fracture classification systems (Garden, Gustilo, Neer for humerus) and the Ottawa Rules, as these are frequently tested with direct recall or scenario-based questions. Focus on the decision-making steps for septic arthritis: aspiration order, antibiotic choice, and urgency of washout. For paediatric orthopedics, commit to SUFE and DDH screening protocols, including age-specific management. Practice interpreting X-ray findings for common fractures (e.g., Colles', scaphoid, ankle) and recognising avascular necrosis signs (e.g., crescent sign in femoral head). Questions often present as clinical vignettes requiring you to choose the next best step in diagnosis or management—not just the diagnosis. Review the NICE guidelines for fracture management and osteoporosis. Spend time on complications like compartment syndrome and fat embolism, as these are high-yield for emergency scenarios.

Practise it: MedLumen has 75 Orthopedics questions for the DHA, each with a full explanation and references.