Fascia iliaca block

Surgical approach (where relevant)

• Not a surgical operation; used to facilitate/optimise care around hip/femur surgery and ED management
• Typical perioperative contexts
  • Neck of femur fracture: pre-op analgesia, positioning for spinal, opioid-sparing, delirium reduction strategy
  • Femoral shaft fracture, femoral neck/acetabulum injuries (variable coverage)
  • Post-op analgesia after hip arthroplasty/hip fracture fixation (as part of multimodal plan)

Anaesthetic management (typical scenarios)

• Type of anaesthesia
  • Analgesic regional block; performed awake/sedated; commonly adjunct to spinal for NOF fracture surgery
  • Can be used with GA or neuraxial; does not replace anaesthesia for surgery
• Airway (if in theatre)
  • If GA: ETT or SGA depending on surgery/aspiration risk; NOF patients often higher aspiration risk and frail—individualise
• Duration
  • Block performance: ~5–10 min (ultrasound), onset typically 10–30 min depending on LA and volume
  • Analgesia duration: ~6–18 h (agent dependent; longer with adjuncts/catheters)
• How painful is the underlying condition/surgery?
  • Hip fracture and femoral fractures: severe pain; movement/positioning very painful; high opioid sensitivity in elderly
  • Hip arthroplasty/fixation: moderate–severe post-op pain; multimodal analgesia required

Indications and aims

• Analgesia for hip fracture, femoral fractures, anterior thigh pain; facilitates positioning for spinal/transfer/imaging
• Opioid-sparing in frail elderly (reduce nausea, respiratory depression, delirium risk; improve mobilisation/physio participation)
• Can be delivered as single-shot or catheter (continuous infusion/intermittent bolus) for ongoing analgesia

Relevant anatomy (exam core)

• Target plane: beneath fascia iliaca, superficial to iliopsoas muscle (iliacus) in the iliac fossa
• Nerves potentially affected
  • Femoral nerve (L2–L4): anterior thigh sensation; quadriceps motor; contributes to hip pain
  • Lateral femoral cutaneous nerve (L2–L3): lateral thigh sensation
  • Obturator nerve (L2–L4): medial thigh sensation; adductor motor; often inconsistently blocked with classic infra-inguinal FIB
    • More reliable obturator coverage with proximal/“supra-inguinal” approach (spread towards lumbar plexus)
• Key landmarks/structures on ultrasound (infra-inguinal approach)
  • Femoral artery (medial), femoral nerve (lateral to artery, under fascia iliaca), iliopsoas muscle deep
  • Fascia lata (superficial) and fascia iliaca (deeper) are two distinct hyperechoic lines
• Dermatomal/clinical effect (typical)
  • Reduced pain from hip fracture/anterior thigh; variable lateral thigh numbness; quadriceps weakness possible

Techniques (what you should be able to describe in a viva)

• Approaches
  • Infra-inguinal (classic): injection below fascia iliaca lateral to femoral nerve/artery at inguinal crease
  • Supra-inguinal: injection cephalad to inguinal ligament to encourage proximal spread (better LFCN/obturator coverage)
  • Landmark (loss-of-resistance “two pops”): less reliable and higher risk of failure/complications vs ultrasound
• Ultrasound-guided infra-inguinal: stepwise
  • Position: supine; slight external rotation; expose inguinal region; consider analgesia/sedation cautiously
  • Probe: high-frequency linear; transverse at inguinal crease; identify femoral artery then femoral nerve lateral
  • Identify fascia lata and fascia iliaca; aim needle tip under fascia iliaca (not just under fascia lata)
  • Needle: in-plane lateral-to-medial commonly; aspirate; hydrodissect with small aliquots to confirm correct plane
  • Inject large volume to promote spread laterally/cephalad; observe separation of fascia iliaca from iliopsoas and spread around femoral nerve
• Supra-inguinal: stepwise (high-yield differences)
  • Probe placed just medial to ASIS, oriented to visualise iliacus muscle and fascia iliaca; needle advanced to plane deep to fascia iliaca
  • Aim for cranial spread towards iliac fossa/lumbar plexus to improve LFCN and obturator involvement

Local anaesthetic choice, dose and practical prescribing (UK exam style)

• Principle: FIB is a fascial plane block → success depends on volume and correct plane more than precise nerve contact
• Typical single-shot volumes (adult)
  • Infra-inguinal: 30–40 mL commonly used (adjust to patient size, frailty, and maximum safe dose)
  • Supra-inguinal: often 30–40 mL; may achieve better proximal spread at similar volumes
• Common LA regimens (examples; always calculate maximum safe dose and consider frailty)
  • Ropivacaine 0.2–0.375% 30–40 mL (good sensory with less motor than bupivacaine at equipotent doses)
  • Levobupivacaine 0.25% 30–40 mL (longer duration; more motor block possible)
  • Lidocaine 1% (with/without adrenaline) for faster onset if needed; shorter duration
• Adjuvants
  • Dexamethasone (perineural/off-label) may prolong duration; consider local policy and consent
  • Avoid mixing multiple LAs without clear rationale; increases dosing complexity and toxicity risk
• Catheter technique (if used)
  • Thread catheter 3–5 cm in plane under fascia iliaca; secure well; label; document sensory/motor baseline
  • Infusion examples: ropivacaine 0.2% at 5–10 mL/h or intermittent bolus per local protocol; monitor quadriceps strength and falls risk

Contraindications and precautions

• Absolute
  • Patient refusal, allergy to LA, infection at injection site
• Relative / caution
  • Anticoagulation: FIB is a superficial fascial plane block (generally lower bleeding risk than deep plexus blocks) but still consider compressibility, local policy, and patient-specific risk
  • Sepsis/systemic infection (risk–benefit); altered anatomy; previous groin surgery
  • Severe hypovolaemia/shock: prioritise resuscitation; avoid masking evolving compartment/ischemic pain (rare context)
  • Pre-existing femoral neuropathy: document baseline deficits; counsel re attribution

Complications and how to reduce them

• Local anaesthetic systemic toxicity (LAST)
  • Risk increased by large volumes, frailty, low body weight, hepatic dysfunction, inadvertent intravascular injection
  • Mitigation: dose calculation, incremental injection with aspiration, ultrasound visualisation, consider adrenaline marker dose if appropriate, monitoring
  • Management: stop injection, call for help, airway/oxygen/ventilation, treat seizures, lipid emulsion, manage arrhythmias per guidelines
• Vascular puncture/haematoma
  • Avoid medial needle trajectory; identify femoral vessels; use colour Doppler if uncertain; compress if puncture
• Nerve injury
  • Less likely than femoral nerve block (needle not aimed at nerve), but still possible; avoid intraneural injection; stop if pain/paraesthesia/high pressure
• Block failure / incomplete analgesia
  • Common causes: injection above fascia iliaca (only under fascia lata), inadequate volume, poor spread, wrong approach for pain source (posterior hip pain)
  • Management: reassess anatomy, consider repeat under ultrasound within safe dosing, add systemic analgesia, consider alternative blocks (PENG, femoral, LPB) depending on indication and expertise
• Motor weakness and falls risk
  • Quadriceps weakness can occur; ensure mobilisation plan accounts for this; document and communicate to ward/physio; consider lower concentration/ropivacaine
• Infection (especially catheters)
  • Asepsis, sterile probe cover/gel, secure dressing, daily review and timely removal

Comparison with related blocks (frequent viva theme)

• FIB vs femoral nerve block
  • FIB: fascial plane, larger volume, potentially covers femoral + LFCN (± obturator), less needle-near-nerve; good for hip fracture pathways
  • Femoral nerve block: targeted femoral nerve, reliable anterior thigh analgesia, more direct motor block; may miss LFCN/obturator
• FIB vs PENG block (pericapsular nerve group)
  • PENG aims at articular branches to anterior hip capsule (femoral, obturator, accessory obturator) and may be more motor-sparing; technique-dependent and evolving evidence base
  • FIB is simpler, widely taught; may provide broader cutaneous coverage but can cause quadriceps weakness
• FIB vs lumbar plexus block
  • Lumbar plexus block is deep, higher bleeding/neuraxial spread risk; requires expertise; stronger analgesia/coverage but greater complication profile

Documentation and governance (often tested indirectly)

• Record: indication, consent, side, technique (US/landmark), needle approach, LA drug/concentration/volume, total dose (mg), aspiration, complications, sensory/motor assessment, post-block instructions
• Communicate falls risk and mobilisation advice; ensure ward knows block performed and expected duration