Regional Anaesthesia Techniques

Regional anaesthesia covers the neuraxial techniques (spinal and epidural) and the peripheral nerve blocks that give targeted anaesthesia and analgesia for orthopaedic procedures. It has become integral to Enhanced Recovery After Surgery (ERAS) protocols and to multimodal analgesia.

What it offers. Compared with systemic opioids it gives superior analgesia and reduces opioid consumption, and less opioid means less postoperative nausea and vomiting (PONV). Motor-sparing blocks allow earlier mobilisation, hospital stay is shorter, and patients are more satisfied.

How practice evolved. From the 1970s to the 1990s blocks were placed by anatomical landmarks and the nerve stimulator. Ultrasound guidance arrived in the 2000s and brought direct visualisation and real-time needle placement, and from the 2010s motor-sparing blocks (adductor canal, IPACK, PENG) followed. Continuous catheter techniques prolong analgesia after complex surgery.

The block follows the operation. In the upper limb the interscalene block serves the shoulder, the supraclavicular and infraclavicular blocks the elbow and forearm, and the axillary block the hand. In the lower limb the femoral, adductor canal, sciatic and popliteal blocks do the work.

Neuraxial anatomy

Where the cord ends. The spinal cord ends at L1-L2 in adults and at L3 in children, while the dural sac continues to S2. Total CSF volume is 120-150 mL.

The epidural space. In the lumbar region it measures 3-5 mm, and the ligamentum flavum is the key resistance met on the way in. It contains fat, which cushions; lymphatics and Batson's venous plexus; blood vessels, the source of the haematoma risk; and the nerve roots exiting at each level, with the dural cuffs where local anaesthetic spreads.

Brachial plexus

The plexus runs from the roots (C5-T1) to the terminal branches, and each level has its own block. Where the needle meets the plexus decides what is covered.

Lower limb

Lumbar plexus (L1-L4). It lies within psoas major and is blocked in the psoas compartment or beneath the fascia iliaca.

• Femoral nerve (L2-L4): anterior thigh and knee
• Lateral femoral cutaneous nerve (L2-L3): lateral thigh
• Obturator nerve (L2-L4): medial thigh and hip

Sacral plexus (L4-S3). The sciatic nerve divides in the popliteal fossa into the tibial and common peroneal nerves, and it is blocked at gluteal, subgluteal or popliteal level.

• Sciatic nerve (L4-S3): posterior thigh, leg and foot
• Posterior femoral cutaneous nerve (S1-S3): posterior thigh
• Pudendal nerve (S2-S4): perineum

Fascial planes

Fascial spread is the key to a successful block.

Upper limb. The interscalene groove lies between the anterior and middle scalenes. At the first rib the plexus forms a nerve cluster in the supraclavicular fossa, below the clavicle the infraclavicular space lies deep to the pectoralis muscles, and in the axilla the sheath is a continuation of the prevertebral fascia.

Lower limb. The fascia iliaca covers the femoral nerve and allows the block to spread. In the popliteal fossa the dividing sciatic nerve is surrounded by fat, and at the ankle the nerves are superficial and lie in several compartments. The IPACK block uses the interspace between the popliteal artery and the knee.

Regional techniques are grouped as neuraxial, peripheral or local.

Upper limb blocks. Besides the four brachial plexus blocks, the suprascapular block covers the shoulder with limited motor block. At the wrist the median nerve block covers the palmar thumb, index and middle fingers, the ulnar block the palmar and dorsal ulnar hand, and the radial block the dorsal radial hand. Digital blocks anaesthetise individual fingers, and WALANT avoids a formal block altogether.

Lower limb blocks. The lumbar plexus (psoas) block serves THA and femur fractures, the fascia iliaca block hip fractures and anterior THA, the femoral nerve block knee surgery and femur fractures, and the PENG block the hip. The lateral femoral cutaneous nerve can be blocked for thigh graft harvest and the saphenous nerve for the medial leg and ankle. Below the knee, the sciatic block by its several approaches serves below-knee surgery, the popliteal sciatic block the foot and ankle, and the ankle block (five nerves) the foot.

How they work. Local anaesthetics bind to voltage-gated sodium channels, preventing depolarisation of the nerve fibre and so blocking propagation of the action potential. Of the agents below, only chloroprocaine is an ester; the rest are amides.

Differential blockade. Small fibres are blocked first, the C fibres carrying pain and the A-delta fibres carrying temperature. Large fibres, motor (A-alpha) and proprioceptive, are blocked last, which explains why sensory block comes before motor block.

Adjuncts that prolong the block.

• Adrenaline (1:200,000 to 1:400,000) vasoconstricts, prolonging the block by 30-50% and reducing systemic absorption, which lowers the LAST risk. It also marks an intravascular injection by causing tachycardia. Avoid it in the interscalene block, where it prolongs the phrenic palsy.
• Dexamethasone (4-8 mg) prolongs the block by 30-50% and, being anti-inflammatory, reduces postoperative pain; perineural and IV routes are both effective. Perineural use prolongs the block by 8-12 hours but is off-label and controversial, while IV use adds 4-8 hours and is the safer option.
• Clonidine (1-2 mcg/kg, or 75-150 mcg), an alpha-2 agonist, prolongs sensory and motor block with a modest effect, at the cost of hypotension and sedation. It is less commonly used with longer-acting agents.
• Dexmedetomidine (50-100 mcg) gives modest prolongation, with sedation.

Adjuncts that do not help. Perineural opioids give no significant benefit and add systemic side effects, ketamine has no proven perineural benefit, and the evidence for magnesium is limited. Sodium bicarbonate speeds onset but does not prolong the block, and hyaluronidase may speed onset but shorten duration.

Spinal anaesthesia (subarachnoid block)

Technique. With the patient sitting or in the lateral decubitus position, the needle enters the L3-L4 or L4-L5 interspace, below the conus medullaris at L1-L2. A 25G or 27G pencil-point needle (Whitacre, Sprotte) reduces post-dural puncture headache (PDPH), and CSF flow is the endpoint. The lower-limb dose is 10-15 mg of heavy 0.5% bupivacaine.

Onset and duration. Onset takes 5-10 minutes. The block lasts 90-150 minutes with plain solution and 120-180 minutes with heavy bupivacaine and an opioid.

Uses. Total hip and knee arthroplasty, lower-limb fracture fixation, and foot and ankle surgery.

Strengths and costs. The block is rapid in onset, dense in both motor and sensory fibres and predictable in duration, and the controlled hypotension reduces blood loss. Against that, the duration of a single shot is fixed, sympathetic blockade causes hypotension, urinary retention can follow, and a dural puncture with a large needle risks headache.

Epidural anaesthesia

Technique. The needle goes in at lumbar level (L2-L3, L3-L4) for the lower limb, or thoracic level for upper abdominal and thoracic surgery. A 16-18G Tuohy needle finds the epidural space by loss of resistance to saline or air, and a catheter threaded through it allows continuous infusion of bupivacaine 0.25-0.5% or ropivacaine 0.2-0.5%.

Onset and duration. Onset takes 15-30 minutes, and with a catheter the block is continuous.

Uses. Major lower-limb surgery (bilateral TKA, complex trauma), postoperative analgesia after spine surgery, and rib fractures (thoracic epidural).

Strengths and costs. The block is titratable, continuous through the catheter and usable for postoperative analgesia, and its gradual onset keeps the circulation stable. It is slower in onset than a spinal, needs more drug, carries the risk of epidural haematoma under anticoagulation, and can be patchy, with a 5-10% failure rate.

Combined spinal-epidural (CSE)

The spinal component gives rapid onset and the epidural catheter prolonged analgesia, placed needle-through-needle or through separate spaces. It suits surgery of long or unpredictable duration and operations after which postoperative analgesia is required, such as THA and TKA.

Contraindications to neuraxial block are set out with the others under Clinical Assessment, and anticoagulant timing has its own section.

The four brachial plexus blocks step down the plexus from the roots to the terminal branches, as laid out in the organisation table under Anatomy.

InterscaleneSupraclavicularInfraclavicularAxillary

Interscalene block (ISB)

Target. The brachial plexus roots at the level of the cricoid cartilage, between the anterior and middle scalene muscles. It blocks C5, C6 and C7, primarily the superior trunk, and often misses C8 and T1, the ulnar territory of the hand.

Uses. Shoulder surgery (rotator cuff, arthroplasty, arthroscopy), proximal humeral fractures and clavicle fractures.

Technique. With the patient supine and the head turned away, a high-frequency linear probe is placed transversely on the lateral neck at the cricoid level, where the roots lie between the scalenes like "traffic lights". The needle goes in-plane or out-of-plane, and 15-20 mL of 0.5% ropivacaine or bupivacaine is injected.

What to expect. Onset takes 15-30 minutes, and the block lasts 12-18 hours as a single shot or 48-72 hours with a catheter. It covers the shoulder and proximal arm, with incomplete coverage of the hand.

Complications.

• Phrenic nerve palsy: temporary hemidiaphragm paralysis in 100%
• Horner syndrome (ptosis, miosis, anhidrosis): 25-75%
• Recurrent laryngeal nerve block (hoarseness): 5-10%
• Vertebral artery injection: rare but catastrophic
• Pneumothorax: under 1% with ultrasound

The phrenic nerve decides who can have it. Avoid bilateral ISB, which risks bilateral phrenic palsy and respiratory compromise, and take care in respiratory disease such as COPD and obstructive sleep apnoea. Low-volume techniques (5-10 mL) reduce phrenic nerve involvement.

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Supraclavicular block (SCB)

Target. The trunks and divisions at the level of the first rib, above the clavicle and lateral to the subclavian artery. It blocks all five terminal nerves and gives the most consistent coverage of the entire upper limb, which earns it the name "the spinal of the arm".

Uses. Elbow, forearm and hand surgery, and proximal radius and ulna fractures.

Technique. With the patient supine, the head turned away and the arm at the side, a linear probe in the supraclavicular fossa shows the plexus as a "bunch of grapes" lateral to the artery, on top of the first rib. The needle goes in-plane from lateral to medial, and 20-25 mL of 0.5% ropivacaine or bupivacaine is injected.

What to expect. Onset takes 15-25 minutes and the block lasts 12-18 hours, covering the complete arm from shoulder to hand.

Complications.

• Pneumothorax: under 1% with ultrasound, against 5% with the landmark technique
• Phrenic nerve palsy: 50-60%, less than with ISB
• Horner syndrome: 10-30%
• Vascular puncture: the subclavian artery is close by

Against the interscalene. It gives more complete distal coverage of the hand from a single injection site and blocks the ulnar nerve reliably.

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Infraclavicular block (ICB)

Target. The lateral, posterior and medial cords surrounding the axillary artery below the clavicle, 2-4 cm from the skin.

Uses. Elbow, forearm and hand surgery, and radius and ulna fractures.

Technique. With the patient supine and the arm abducted, the probe sits below the clavicle, medial to the coracoid. The needle goes in-plane from cephalad or caudad, and 20-30 mL is injected (0.375-0.5% ropivacaine).

What to expect. Onset takes 20-30 minutes and the block lasts 12-18 hours, covering the elbow to the hand and often sparing the shoulder.

Trade-offs. The flat surface makes catheter placement easier, the pneumothorax risk is lower than with SCB, and the arm can be immobilised for comfort. The block is deeper and more technical, onset is slower than with SCB, and the pectoralis muscle lies in the way.

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Axillary block

Target. The terminal nerves around the axillary artery: median anteriorly, ulnar medially and radial posteriorly, with the musculocutaneous nerve lying separately within coracobrachialis.

Uses. Hand, wrist and distal forearm surgery.

Technique. With the patient supine and the arm abducted 90 degrees, a high-frequency probe is placed in the axilla. Each nerve is approached in-plane in a multi-injection technique, 30-40 mL in total (0.5% ropivacaine).

What to expect. Onset takes 20-30 minutes and the block lasts 12-16 hours, covering the mid-forearm to the hand.

Trade-offs. There is no risk of pneumothorax and no phrenic nerve involvement, and the block is superficial and safe, good for hand surgery. It needs multiple injections, leaves the shoulder and upper arm uncovered, risks median nerve palsy close to the artery, and may miss the musculocutaneous nerve if it is not specifically targeted.

Intravenous regional anaesthesia (IVRA, Bier block)

The Bier block is a simple, reliable technique for short distal-limb procedures (hand and forearm, and occasionally foot) that needs no nerve localisation.

Technique. An IV cannula is sited in the operative hand or foot, the limb is exsanguinated (elevation, then an Esmarch bandage), and a double (two-cuff) tourniquet is inflated above arterial pressure. Dilute lidocaine or prilocaine (for example 0.5% lidocaine, roughly 3 mg/kg) is then injected through the cannula; it diffuses from the vasculature into the nerves and produces anaesthesia distal to the cuff within about 5-10 minutes.

The two cuffs. The proximal cuff is inflated first. Once the block is established the distal cuff, now over anaesthetised skin, is inflated and the proximal cuff released to relieve tourniquet pain.

Deflation is the danger. Letting the cuff down releases the sequestered local anaesthetic into the systemic circulation as a bolus and risks LAST. The cuff must therefore stay inflated for a minimum of around 20-30 minutes however quickly surgery finishes, and at the end it is deflated in cycles (deflate, reinflate) while watching for toxicity. This hazard is why bupivacaine, which is cardiotoxic, must never be used for IVRA. The tourniquet-use topic covers cuffs and pressures.

Uses and limits. Fast, technically easy, with high success and rapid recovery, it is ideal for day-case carpal tunnel release, ganglion excision or fracture manipulation. Anaesthesia lasts only while the cuff is up, so there is no postoperative analgesia; tourniquet pain limits it to roughly an hour; and it is unsuitable when a bloodless field is needed beyond tourniquet tolerance.

WALANT (wide-awake local anaesthesia, no tourniquet)

WALANT is a hand, and increasingly foot, technique that uses local anaesthetic with adrenaline alone: no tourniquet, no sedation and no formal block, so the patient is fully awake and comfortable.

Technique. Lidocaine (e.g. 1%) with adrenaline (e.g. 1:100,000) is infiltrated subcutaneously along the planned operative field in a tumescent approach, usually buffered with bicarbonate to reduce the sting of injection. Waiting about 25-30 minutes for maximal adrenaline vasoconstriction gives a near-bloodless field without a tourniquet.

Adrenaline in the fingers. The old teaching that adrenaline is dangerous in the fingers has been refuted: large series show that lidocaine with adrenaline is safe in the digits, and phentolamine is available as a rescue reversal agent if vasoconstriction is excessive. That removed the rationale for the tourniquet and sedation in many hand procedures.

Why use it. The patient can actively move the hand during the operation, which is invaluable for flexor tendon repair (testing the repair for gliding and gapping), tenolysis and tendon transfers. There is no tourniquet pain and therefore no sedation, no general or neuraxial anaesthetic and no fasting, and it is efficient and low-cost, suited to minor-procedure and office settings.

Typical uses. Carpal tunnel release, trigger-finger release, flexor and extensor tendon repair, fracture K-wiring and Dupuytren surgery.

The evidence. Ultrasound has become the standard of care for most peripheral nerve blocks. In the Abrahams meta-analysis (BJA 2009), compared with nerve stimulation it reduced block failure (RR 0.41, 95% CI 0.26-0.66) and vascular puncture (RR 0.16, 95% CI 0.05-0.47), made onset 29% faster and the block 25% longer, and improved block density and coverage. The trials were not powered to prove a reduction in LAST.

Why it is safer. The operator sees the nerves and the vessels, pleura and peritoneum around them, tracks the needle in real time to prevent vascular puncture, and confirms that the spread is adequate. If the injection is intravascular or intraneural, it can be stopped.

Probes. High-frequency linear probes (8-15 MHz) image superficial structures under 4 cm and serve most blocks, while low-frequency curvilinear probes (2-5 MHz) image deep structures over 4 cm. Compound imaging improves tissue definition, Doppler identifies vessels to avoid, and 3D/4D imaging is emerging for complex anatomy.

Reading the image. Nerves appear as round or oval honeycomb structures, multiple hypoechoic fascicles within a bright hyperechoic rim. Arteries are pulsatile and non-compressible, veins compressible and non-pulsatile, fascia forms hyperechoic lines, and muscle is striated and contracts. Understanding this sonoanatomy is now essential.

A good injection. Local anaesthetic spreads circumferentially around the nerve, the "donut sign", and separates it from the adjacent structures. Slight distension of the nerve during injection can accompany a successful block.

Injection pressure. Normal injection pressure is under 15 psi, and higher pressure (over 15-20 psi) suggests intraneural injection. It can be judged with a commercial opening-pressure device or by syringe feel, and the needle is repositioned before injection is attempted again.

The nerve stimulator. In modern practice ultrasound is primary and the stimulator an adjunct, not mandatory, used to confirm the identity of a nerve. Start at 0.5-1.0 mA and look for a motor twitch at 0.3-0.5 mA. No response at 0.2 mA indicates a good position, not intraneural, while a twitch below 0.2 mA may mean the needle is intraneural and should be repositioned.

Training. Basic skills take 20-30 blocks, competency 50-100 and expert level 200 or more. The recommended pathway runs from didactic learning (anatomy, physics) through simulation and phantom practice and supervised clinical practice to independent practice with backup.

History. Ask about allergies (local anaesthetics, latex, antiseptics), anticoagulation (type, dose and timing of the last dose), previous blocks (success, complications, nerve injury), and cardiac, respiratory and neurological comorbidity. Note anything that affects consent, such as language, comprehension or anxiety.

Examination. Look for infection at the proposed site and for skin lesions, scarring or burns, and assess the landmarks, any deformity, body habitus and peripheral vascular disease. Examine and document any pre-existing neurological deficit before the block.

Contraindications

Consent. Describe the procedure and its expected benefits (pain relief, opioid sparing), the common risks (bruising, numbness, discomfort) and the serious ones (LAST, nerve injury, infection), the alternatives (GA, IV analgesia, other blocks) and when sensation will return. Record the risks discussed for that block, the pre-existing motor and sensory examination, the patient's understanding and any concerns, and have the consent signed before sedation.

Bleeding into a confined space. The risk is not just bleeding but bleeding in a confined space, as when an epidural haematoma compresses the cord. Superficial sites can be compressed and deep sites cannot, so the block type sets the level of risk.

• Compressible sites (lower risk): axillary (superficial), femoral (below the inguinal ligament), popliteal, ankle (multiple superficial sites), and wrist or digital blocks (very low risk)
• Non-compressible sites (higher risk): neuraxial (catastrophic if a haematoma forms), lumbar plexus (deep within psoas), infraclavicular (behind the clavicle, near vessels), supraclavicular (risk of subclavian puncture) and deep cervical plexus (near the vertebral artery)

Catheters. Remove the catheter before restarting anticoagulation, wait the same interval after removal as for block placement, and observe for 4 hours after removal for signs of haematoma.

Deciding at the bedside. Identify the block type (neuraxial, deep or superficial peripheral) and the anticoagulant (type, dose, last administration), then apply ASRA and local guidelines. Consider the alternatives, superficial blocks, GA or multimodal analgesia, and document the risk-benefit discussion.

Test only what will change management. Routine screening is not required for healthy patients having peripheral blocks, and coagulation testing is needed only if the patient is anticoagulated or coagulopathy is suspected clinically.

The ultrasound pre-scan. Now standard of care for most peripheral blocks, the pre-scan finds the nerve's location and depth, maps the vessels to avoid puncture, and detects pathology such as cysts, tumours or anomalies. It also plans the needle trajectory, and the patient's habitus guides the choice of probe and needle.

Other imaging. Fluoroscopy can guide lumbar plexus and neuraxial blocks but is not routine, CT guidance helps with complex anatomy or tumours, and MRI serves pre-procedural planning, not real-time guidance. Injection pressure monitoring is a safety adjunct.

Algorithm

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Planning a block. Work through six questions:

1. What surgery? The site determines which nerves to block and the sensory and motor requirements.
2. How long? The duration of surgery and the postoperative analgesic need decide between a single shot with a long-acting agent and a catheter.
3. Ambulatory or inpatient? Motor-sparing blocks suit ambulation.
4. Anticoagulated? This governs site selection and timing, and deep blocks are contraindicated.
5. What comorbidities? In respiratory disease avoid a phrenic block and avoid bilateral interscalene blocks; consider cardiac disease too.
6. What multimodal plan? Integrate the block with paracetamol, NSAIDs and gabapentinoids.

The best block is the one that provides adequate analgesia with minimal motor impairment for the specific surgery and patient.

Block selection by surgery

Block timing

Multimodal analgesia

Before surgery.

• Paracetamol 1 g orally
• An NSAID if not contraindicated (e.g. celecoxib 200-400 mg)
• A gabapentinoid, pregabalin 75-150 mg, which reduces opioid requirement
• Dexamethasone 8 mg IV, which extends the block and is antiemetic
• Midazolam 1-2 mg for anxiolysis if needed

During and after surgery.

• The regional block as planned for the surgery, with LIA as an adjunct or alternative
• Regular paracetamol 1 g four times daily, and NSAIDs continued if tolerated
• Oxycodone 5-10 mg as needed for breakthrough pain
• Antiemetics: ondansetron, dexamethasone

Preparation. Apply monitoring (SpO2, ECG, blood pressure) before any sedation, and secure IV access, which is essential before any block. Have resuscitation equipment and lipid emulsion available, use sterile technique (skin preparation, sterile probe cover), and position the patient comfortably with access to the block site.

Equipment. A high-frequency linear ultrasound probe suits most blocks, and a nerve stimulator is an adjunct. Block needles are 50-100 mm, echogenic preferred, and the local anaesthetic is pre-drawn in labelled syringes, with extension tubing for aspiration and injection.

If in doubt, don't inject. Never inject when unsure where the needle tip is, and stop and reassess if the patient reports paraesthesia or severe pain.

Continuous catheters

When to use one. A catheter is for analgesia needed for more than 24 hours: major surgery (TKA, THA, shoulder reconstruction), trauma (rib fractures, complex fractures), chronic cancer pain, and sympathetic block to improve perfusion.

What goes wrong. Dislodgement needs repositioning in 5-10%, infection risk rises after 72-96 hours, local anaesthetic can leak around the site, and motor block may impair rehabilitation. The infusion runs from an elastomeric or electronic pump.

Mechanism. In the CNS, local anaesthetic inhibits the inhibitory neurons first, producing excitation, and then all neurons, producing depression. In the heart it blocks sodium and potassium channels and dysregulates calcium. The lipid sink theory holds that lipid emulsion sequesters local anaesthetic from the tissues.

Who is at risk.

• A high total dose, exceeding the maximum recommended
• Accidental intravascular injection, especially into an artery
• A highly vascular site, such as intercostal or paracervical blocks
• Extremes of age, cardiac disease, hepatic dysfunction and low-protein states

Which agent. Bupivacaine has the highest cardiotoxicity, ropivacaine is intermediate, and lidocaine is the least toxic.

Presentation

LAST progresses in stages, and the CNS signs come before the cardiac ones:

• CNS excitation: perioral numbness, metallic taste, tinnitus, visual disturbances, agitation and confusion, muscle twitching
• CNS depression: seizures, loss of consciousness, respiratory depression, coma
• Cardiovascular toxicity: bradycardia, hypotension, arrhythmias (ventricular tachycardia, fibrillation) and cardiac arrest, which is often resistant to standard ACLS

Management

Immediate actions.

1. Stop injecting local anaesthetic.
2. Call for help: LAST is a team emergency.
3. Manage the airway with 100% oxygen, ventilating or intubating if needed and avoiding hyperventilation.
4. Suppress seizures with benzodiazepines, not propofol initially.
5. Give 20% lipid emulsion (Intralipid or equivalent), the first-line treatment.

Cardiac arrest. Start CPR by the ACLS protocol and continue lipid emulsion throughout the resuscitation. Give adrenaline only in small doses (under 1 mcg/kg) and avoid vasopressin, which may worsen cardiac toxicity. Resuscitation may take over 60 minutes, so do not give up early.

After resuscitation. Observe for at least 4-6 hours (12-24 hours if severe), monitoring the ECG, cardiac enzymes and lipid levels, because toxicity can recur as local anaesthetic redistributes from the tissues.

Prevention

• Use ultrasound guidance, which reduces accidental intravascular injection and the volume of local anaesthetic required
• Calculate the weight-based maximum dose before drawing up, and respect it
• Aspirate for blood before injecting
• Fractionate the injection into 3-5 mL aliquots with aspiration and pauses, which allows an intravascular injection to be detected
• Divide the total dose between blocks or sites when several are needed
• Add adrenaline 1:200,000 as a marker or test dose: a rising heart rate suggests intravascular injection
• Talk to the patient and ask about symptoms during injection

Sudden deterioration after a block

Acute collapse or distress shortly after local anaesthetic injection has a focused differential, and telling the causes apart quickly matters because their management differs.

Neuraxial complications

Peripheral nerve block complications

How often. Nerve injury occurs in under 1 in 1,000 blocks, fewer with ultrasound, and vascular injury in under 1 in 500, usually a self-limiting haematoma. The block fails to give complete anaesthesia in 5-10%. Block-specific complications, such as phrenic palsy and pneumothorax, are listed with each block; the lumbar plexus block adds epidural spread and renal injury.

Other problems. Infection is rare after a single shot and more likely with catheters, and a retained catheter may need imaging and extraction. True allergy is rare, and commoner with esters than amides.

Managing a new deficit. Document it at once and compare it with the pre-block examination. Most resolve within 4-6 weeks; if symptoms persist, obtain EMG/NCS at 3-4 weeks and refer to a specialist if there is no improvement by 6 weeks, with neurology or hand surgery review for persistent or worsening deficits.

Minimising the risk. Use ultrasound guidance, avoid injecting against high resistance, stop if the patient reports severe pain, respect the anatomy without excessive force, and use atraumatic needles.

Protecting the insensate limb. Position it to prevent nerve compression, protect it from heat, cold and sharp objects, and support weight-bearing with crutches if the leg is blocked; the patient receives written instructions. An arm block needs a sling, gait training with physiotherapy waits until the block resolves, and DVT prophylaxis continues despite immobility. Record the expected time of block resolution.

Discharge after a peripheral block. Protective sensation must be returning or the limb protected, and a responsible adult should be at home for the duration of the block. After a motor-blocking block such as a femoral block, provide crutches or gait aids and clear instructions about the fall risk, and consider an overnight stay for a high-risk patient.

Continuous catheter management

Regimens. A background infusion of 5-10 mL/hour (0.1-0.2% ropivacaine) with patient-controlled demand boluses (5 mL every 30-60 minutes) is the commonest arrangement. Intermittent boluses of 10-15 mL every 4-6 hours use less local anaesthetic and potentially spread better, and lower concentrations (0.1-0.15%) spare motor function.

Troubleshooting. For inadequate analgesia, check the position with ultrasound and bolus through the catheter; for motor block, reduce the concentration or switch to intermittent boluses. Leakage needs the dressing resecured and may need a new catheter, and a disconnected catheter is not reconnected because of the contamination risk.

Infection. Inspect the site daily and teach the patient to report redness, discharge or fever. Consider removal at 72-96 hours, and remove the catheter immediately if it is infected, sending it for culture and giving antibiotics if there is cellulitis; chlorhexidine-impregnated dressings may reduce infection.

Transition to oral analgesia

Motor-sparing trends. IPACK adds posterior knee coverage, PENG gives hip analgesia without motor block, suprascapular plus axillary block is an alternative to interscalene, and catheters use lower concentrations such as 0.1% ropivacaine.

What a service should track. A block failure rate under 5% is the target, and LAST should be rare with proper technique. Nerve injuries, most of them transient, falls after femoral and other motor blocks, and catheter infections are each documented and tracked.

OrthoVellum is a worldwide resource: regional anaesthesia is practised on every continent, and the major society guidance is largely convergent. The differences a candidate is most likely to be examined on relate to anticoagulation timing, LAST rescue protocols, and the local availability of ultrasound and lipid emulsion.

Epidemiology and burden

• Local anaesthetic systemic toxicity (LAST) is the most feared complication of regional anaesthesia. Contemporary registry and audit data place clinically apparent LAST in the low single digits per 10,000 peripheral nerve blocks, with severe cardiac events rarer still.
• Permanent peripheral nerve injury after blockade is rare (of the order of 0.02-0.04% at long-term follow-up), with most postoperative neurological deficits being transient and multifactorial (surgery, tourniquet, positioning).
• Adoption of ultrasound guidance has risen to near-universal in high-resource settings; nerve stimulation and landmark techniques remain important where ultrasound is unavailable.

Major guidelines, side by side

LAST rescue: the global consensus

• 20% lipid emulsion is the agreed first-line therapy worldwide and should be stocked wherever local anaesthetic is injected in potentially toxic doses.
• Bolus 1.5 mL/kg then infusion 0.25 mL/kg/min, with repeat boluses for persistent instability and an approximate upper limit of 10-12 mL/kg.
• Reduce adrenaline dosing, avoid vasopressin, calcium channel blockers and beta-blockers, and anticipate prolonged resuscitation with consideration of cardiopulmonary bypass in refractory arrest.

Registry and practice variation

• Regional anaesthesia is not implant-based, so it is not tracked by the arthroplasty joint registries (NJR, AOANJRR, AJRR, SHAR); registry insight instead comes from national audit projects and adverse-event databases.
• High- vs limited-resource settings: where ultrasound machines, single-use block needles or lipid emulsion are scarce, nerve stimulation and landmark spinal anaesthesia remain mainstays, and drug selection favours cheaper agents (lidocaine, bupivacaine) over ropivacaine/levobupivacaine.
• ERAS integration is global: regional anaesthesia is a cornerstone of enhanced recovery for arthroplasty everywhere, with motor-sparing combinations (ACB + IPACK for TKA; PENG or fascia iliaca for hip; interscalene for shoulder) reducing opioid use and enabling early mobilisation.

Regional anesthesia is a cornerstone of modern orthopaedic perioperative care, offering superior analgesia, reduced opioid consumption, and facilitation of early mobilization. The evolution from landmark-based techniques to ultrasound-guided approaches has dramatically improved safety and efficacy.

Key exam points:

• LAST is a life-threatening complication treated with lipid emulsion 20%
• Ultrasound guidance is now standard of care for peripheral nerve blocks
• Motor-sparing blocks (ACB, IPACK, PENG) enable ERAS protocols and same-day mobilization
• Block selection must match surgical site and patient goals
• Anticoagulation timing is critical for neuraxial safety

Future directions include development of novel motor-sparing blocks, longer-acting local anesthetics, and integration of continuous catheter techniques with ambulatory surgery protocols.