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Open Fracture Analgesia — FRCA Final MCQ

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ModerateTrauma & Emergency AnaesthesiaOpen Fracture AnalgesiaFRCA Final

A 30-year-old man (ASA I, 70 kg) has an isolated Gustilo grade IIIA open mid-shaft tibial fracture. Baseline neurovascular and compartment assessment is normal and a protocol of frequent documented reassessment is in place. After morphine 10 mg IV and paracetamol 1 g IV his pain score is 8/10. An ultrasound-guided femoral nerve block has produced definite sensory loss over the medial calf (saphenous distribution) but has not relieved his fracture pain. A further single-shot block using low-concentration local anaesthetic without adjuncts is planned. Which technique is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Popliteal sciatic nerve block

Explanation lettering: C = shown as A · A = shown as B · E = shown as C · B = shown as D · D = shown as E

B is correct. The tibial shaft, periosteum and surrounding compartments are supplied by the sciatic nerve through its tibial and common fibular divisions; the femoral nerve contributes only the saphenous strip over the medial calf, which is already blocked. A popliteal sciatic block therefore completes below-knee coverage and is the logical next step. Fascia iliaca (A) and a repeat femoral block (E) simply duplicate lumbar plexus/femoral territory that is demonstrably working. Adductor canal (D) is essentially a distal saphenous block, adding nothing. Ankle block (C) anaesthetises the foot, not a mid-shaft tibial fracture, and is impractical here. Association of Anaesthetists guidance supports regional analgesia in lower leg trauma using low-concentration local anaesthetic without adjuncts, provided compartment syndrome surveillance is frequent, documented and escalated appropriately, as NICE NG37 requires for 48 hours after tibial fracture.

Reference: Nathanson MH, Harrop-Griffiths W, Aldington DJ, et al. Regional analgesia for lower leg trauma and the risk of acute compartment syndrome: Guideline from the Association of Anaesthetists. Anaesthesia 2021;76(11):1518–1525. https://pubmed.ncbi.nlm.nih.gov/34096035/