Anaes · Regional anaesthesia
Lower limb regional anaesthesia: plexus and peripheral blocks
Also known as lower limb regional blocks
Exam-exhaustive lower-limb regional anaesthesia for ANZCA Final: femoral and fascia iliaca, adductor canal, sciatic and popliteal, obturator, IPACK, ankle block; ultrasound landmarks, dosing principles, LAST rescue, compartment-syndrome surveillance, and ERAS motor-sparing strategy.
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Red flags
- Dense motor block can mask acute compartment syndrome — share the plan with orthopaedics and use dilute solutions or sensory-preferential techniques when risk is high.
- Femoral/adductor canal blocks do not anaesthetise the posterior knee — combine with sciatic or IPACK when needed for TKA.
- Large-volume fascial plane / plexus blocks still risk LAST — lipid 1.5 mL/kg ready.
- Neuraxial and deep blocks require ASRA-compatible anticoagulation timing.
Meet the patient
A sixty-eight-year-old with diet-controlled diabetes on aspirin is listed for a primary total knee arthroplasty on an enhanced-recovery pathway, and the surgeon expects the patient weight-bearing on the day of surgery. The block that earns its place here is not the dense femoral block of a decade ago — it is a motor-sparing adductor canal block plus IPACK plus local infiltration, and the reason is mobilisation: across seven randomised trials (573 knee arthroplasties), adductor canal patients mobilised faster than femoral-block patients (Timed Up and Go mean difference −5.08) with no reduction in analgesia.[5]
Lower-limb regional anaesthesia is a high-yield Final topic because it forces you to think like a consultant: match the nerve territory to the incision, protect the mobilisation goals of an arthroplasty, avoid turning a useful analgesic block into a falls risk or a missed compartment syndrome, and still respect the local-anaesthetic mass and the anticoagulation clock. The examiner rewards a territory-first matrix, not a list of block names.[1]
References5ShowHide
- [1]Neal JM, et al. The Third American Society of Regional Anesthesia and Pain Medicine Practice Advisory on Local Anesthetic Systemic Toxicity: Executive Summary 2017. Reg Anesth Pain Med, 2018.PMID 29356773
- [2]Horlocker TT, et al. Regional Anesthesia in the Patient Receiving Antithrombotic or Thrombolytic Therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (Fourth Edition). Reg Anesth Pain Med, 2018.PMID 29561531
- [3]Donaldson AJ, et al. Bone cement implantation syndrome. Br J Anaesth, 2009.PMID 19059919
- [4]Hilber N, Dodi A, Blumenthal S, et al. The Impact of Regional Anesthesia in Masking Acute Compartment Syndrome after Limb Trauma. J Clin Med, 2024.PMID 38542011
- [5]Gao F, Ma J, Sun W, et al. Adductor Canal Block Versus Femoral Nerve Block for Analgesia After Total Knee Arthroplasty: A Systematic Review and Meta-analysis. Clin J Pain, 2017.PMID 27322397