Total hip replacement

Surgical approach

Usually elective arthroplasty for osteoarthritis; also for inflammatory arthropathy, avascular necrosis, fracture neck of femur (hemiarthroplasty more common), revision surgery
Positioning: commonly lateral decubitus (operative side up); sometimes supine (anterior approach)
- Key anaesthetic implications: pressure area protection, dependent lung ventilation/perfusion, access to airway/lines, risk of nerve/eye injury
Approach: posterior (common), lateral/anterolateral, direct anterior
- Posterior: higher dislocation risk; anterior: potentially less dislocation but different positioning/traction table in some centres
Operative steps (typical): incision → split muscles/capsule → dislocate femoral head → femoral neck osteotomy → acetabular reaming + cup insertion → femoral canal broaching + stem insertion → trial reduction → definitive head/liner → reduction → closure
Fixation: cemented, uncemented, or hybrid
- Cemented components use polymethylmethacrylate (PMMA); risks include bone cement implantation syndrome (BCIS)
Blood loss: moderate; can be significant in revision surgery; cell salvage sometimes used

Anaesthetic management

Type of anaesthesia: Spinal (± sedation) common; GA also common; combined spinal-GA in selected patients
- Spinal advantages: less blood loss/transfusion, lower DVT/PE and pulmonary complications in some studies, good early analgesia; disadvantages: hypotension, urinary retention, limited duration, anticoagulation constraints
- GA advantages: predictable duration, airway control; disadvantages: PONV, delirium risk in frail, more opioids if regional not used
Airway: if GA, usually ETT (lateral position, longer case, need controlled ventilation); SGA may be used in selected uncomplicated cases but less common in lateral positioning
Duration: primary THR typically 1–2.5 hours (longer for complex/revision)
Pain: moderate to severe without multimodal analgesia; significant movement-related pain early post-op
Analgesia strategy: multimodal (paracetamol + NSAID/COX-2 if suitable) + regional (e.g. periarticular local infiltration analgesia (LIA); fascia iliaca block or PENG block in some centres) + opioid-sparing
- Avoid dense motor block that impairs mobilisation if enhanced recovery pathway prioritised
Key intra-op focuses: haemodynamic stability (especially during cementing), temperature management, blood conservation (TXA), thromboprophylaxis planning, delirium prevention

Indications and patient factors

Indications: osteoarthritis (most common), rheumatoid/inflammatory arthritis, avascular necrosis, dysplasia, post-traumatic arthritis; revision for loosening/infection/dislocation
Typical comorbidity profile: older, frail, cardiovascular disease, COPD, CKD, anaemia, obesity, diabetes; often on antiplatelets/anticoagulants
Functional status: exercise tolerance limited by pain; assess cardiorespiratory reserve using history, frailty tools, and investigations where indicated

Preoperative assessment and optimisation

History/exam: cardiorespiratory symptoms, previous anaesthetic issues, OSA screening, cognitive baseline, falls risk, pain regimen/opioid tolerance, alcohol, dentition/airway
Investigations (typical): FBC (anaemia), U&E/eGFR, group & screen; ECG if indicated; HbA1c if diabetic; consider iron studies if anaemic
Anaemia: treat pre-op where possible (iron ± EPO per local pathway); aim to reduce transfusion
Medication management (principles):
- Anticoagulants/antiplatelets: follow local/ASRA/ESA guidance for neuraxial timing; plan bridging only if high thrombotic risk
- ACEi/ARB: consider withholding on day of surgery if risk of refractory hypotension (local policy dependent)
- Diabetes meds: adjust insulin/oral agents; SGLT2 inhibitors usually stopped pre-op to reduce euglycaemic ketoacidosis risk
Consent: discuss neuraxial risks (hypotension, PDPH, nerve injury, haematoma/infection), GA risks, transfusion, BCIS, postoperative delirium, thromboembolism

Choice of anaesthesia: practical options

Spinal anaesthesia: e.g. hyperbaric bupivacaine (dose tailored) ± intrathecal opioid (fentanyl/diamorphine) depending on pathway and side-effect tolerance
- Plan for hypotension: vasopressors ready (metaraminol/phenylephrine), fluid strategy, left uterine displacement not relevant; treat promptly to maintain cerebral perfusion in elderly
GA: balanced technique; consider TIVA in high PONV risk; ensure secure airway for lateral positioning; lung-protective ventilation
Sedation with spinal: titrate carefully in elderly/OSA; maintain airway access in lateral position; capnography if moderate/deep sedation
Regional analgesia adjuncts:
- LIA: surgeon infiltrates periarticular tissues with LA ± adrenaline ± NSAID (e.g. ketorolac) per protocol; check total LA dose
- Fascia iliaca block: may help early pain but can cause quadriceps weakness; consider mobilisation goals
- PENG block: targets articular branches; potentially less motor weakness (evidence evolving); still risk of motor spread

Monitoring, access, and positioning

Monitoring: standard ASA; consider arterial line for significant cardiac disease, anticipated major blood loss, revision surgery, or high BCIS risk
IV access: at least one good-bore cannula; two cannulae for revision/anaemia; blood warmer/rapid infuser if high risk
Positioning (lateral): protect pressure points; axillary roll; check dependent eye/ear; ensure ETT secure; padding for peroneal nerve; avoid excessive neck rotation
Temperature: forced-air warming, warmed fluids; hypothermia increases bleeding, infection, and cardiac events

Blood conservation and thromboprophylaxis

Tranexamic acid (TXA): commonly used (IV ± topical) to reduce blood loss/transfusion; consider contraindications (e.g. recent thrombosis per local policy, seizure risk with high doses)
Cell salvage: consider in revision surgery or anticipated high blood loss; follow local protocols
VTE prophylaxis: mechanical + pharmacological per local orthopaedic policy; coordinate timing with neuraxial procedures
- Key principle: avoid neuraxial puncture/catheter removal in the presence of significant anticoagulant effect

Bone Cement Implantation Syndrome (BCIS)

Definition: peri-cementation cardiorespiratory compromise associated with cemented arthroplasty (also occurs with long-bone cementing)
Pathophysiology: embolisation (fat/marrow/cement/air) → increased PVR → RV failure → reduced LV preload/CO; also mediator release and vasodilation; hypoxia/hypotension/arrhythmias
Timing: classically during femoral canal reaming/pressurisation, cement insertion, prosthesis insertion, or joint reduction
Risk factors:
- Patient: older/frail, ASA 3–4, cardiopulmonary disease (esp pulmonary HTN, RV dysfunction), hypovolaemia, osteoporosis, metastatic disease
- Surgical: cemented femoral component, long-stem prosthesis, revision surgery, pathological fractures, uninstrumented canal, high pressurisation
BCIS severity (commonly used grading):
- Grade 1: SpO2 <94% or SBP drop >20%
- Grade 2: SpO2 <88% or SBP drop >40% or unexpected LOC (if regional)
- Grade 3: cardiovascular collapse requiring CPR
Prevention/mitigation:
- Identify high-risk patients; discuss with surgeon (consider uncemented where appropriate)
- Optimise volume status; avoid hypovolaemia; ensure high FiO2 around cementing; vasopressors drawn up
- Enhanced monitoring in high risk (arterial line; consider cardiac output monitoring/echo availability)
- Surgical measures: medullary lavage, venting, careful pressurisation, haemostasis before cementing
Management (treat as acute RV failure/PE physiology):
- Call for help; 100% oxygen; ensure airway/ventilation; stop surgical stimulus if possible
- Support circulation: vasopressors (noradrenaline/phenylephrine/metaraminol) + consider inotrope for RV (adrenaline; dobutamine in selected settings) guided by haemodynamics
- Fluids: cautious boluses to support RV preload (avoid overload if RV failing); consider echo if available
- Treat arrhythmias; CPR if collapse; post-event ICU/HDU

Postoperative care

Analgesia: continue multimodal; minimise opioids; consider PRN oxycodone/morphine with antiemetic and bowel regimen; assess for neuropathic pain
PONV prophylaxis: risk-stratify; use combination therapy; consider TIVA if high risk
Delirium prevention: avoid benzodiazepines where possible, maintain sleep/wake cues, treat pain, correct hypoxia/hypotension, early mobilisation, glasses/hearing aids
Mobilisation: early physio; avoid prolonged motor block; monitor post-spinal urinary retention (bladder scan pathway)
Complications to monitor: bleeding/anaemia, hypotension, AKI, infection, dislocation, nerve injury, VTE/PE, myocardial injury, stroke

Key complications (anaesthetic perspective)

Haemorrhage and transfusion; dilutional coagulopathy in major revision
BCIS (cemented) and embolic phenomena; acute pulmonary hypertension/RV failure
Hypotension with spinal (especially elderly/dehydrated); myocardial ischaemia from supply-demand mismatch
Nerve injury: sciatic/peroneal (surgical/positioning), femoral (retractors), neuraxial-related neurological injury (rare)
Postoperative delirium/cognitive dysfunction; respiratory depression if opioids/sedation in OSA

You are asked to anaesthetise a 78-year-old for elective cemented total hip replacement. How would you assess and plan the anaesthetic?

Structure: patient factors → surgery factors → anaesthetic options → risk reduction → postoperative plan.

Assess: functional capacity limited by pain; screen for IHD/HF, valvular disease (AS), AF, COPD, OSA, CKD, anaemia, frailty, cognition
Review meds: anticoagulants/antiplatelets and neuraxial timing; ACEi/ARB plan; diabetes meds (SGLT2 stop); chronic opioids
Investigations: FBC/U&E/eGFR, group & screen; ECG ± echo if symptoms/murmur; optimise anaemia
Discuss technique: spinal ± light sedation vs GA; explain risks/benefits and patient preference; plan for lateral positioning and airway access
Blood conservation: TXA; anticipate transfusion needs; consider cell salvage if high risk
BCIS plan for cemented THR: identify risk, communicate with surgeon, high FiO2 during cementing, vasopressors ready, consider arterial line if high risk
Post-op: multimodal analgesia (LIA ± block), delirium prevention, VTE prophylaxis plan coordinated with neuraxial, early mobilisation

Describe bone cement implantation syndrome: definition, risk factors, recognition, and management.

Common FRCA viva topic for cemented hip arthroplasty.

Definition: acute hypoxia ± hypotension ± arrhythmias ± collapse temporally related to cementation/prosthesis insertion
Mechanism: embolic load → ↑PVR → RV failure → ↓LV preload/CO; plus mediator release/vasodilation
Risk factors: frailty/ASA 3–4, cardiopulmonary disease/pulmonary HTN, hypovolaemia; cemented/revision/long-stem/pathological bone
Recognition: sudden fall in ETCO2, SpO2, BP; bronchospasm-like picture; arrhythmias; decreased consciousness under regional
Immediate management: 100% O2, support ventilation, vasopressors/inotropes, cautious fluids, treat arrhythmias, CPR if needed; escalate to ICU/HDU
Prevention: optimise volume, communicate cementing time, high FiO2, invasive monitoring in high risk, surgical lavage/venting/controlled pressurisation

Spinal anaesthesia for THR: what dose/adjuncts might you use, and how would you manage hypotension?

Examiners want principles: titration, physiology, and prompt treatment.

Technique: single-shot spinal with hyperbaric bupivacaine; consider intrathecal opioid (e.g. fentanyl/diamorphine) balancing pruritus/PONV/resp depression
Dose: tailor to height/age/comorbidity; aim adequate block for duration; plan conversion to GA if inadequate/prolonged surgery
Hypotension: anticipate (elderly, hypovolaemia); treat promptly with vasopressors (metaraminol/phenylephrine) and judicious fluids; maintain HR and coronary perfusion
Sedation: minimal effective dose; use capnography; avoid oversedation in lateral position/OSA

How would you provide postoperative analgesia for THR while facilitating early mobilisation?

Focus on multimodal, opioid-sparing, and avoiding motor block.

Baseline: paracetamol + NSAID/COX-2 (if renal/GI/cardiac status allows)
Regional: LIA (common); consider PENG or fascia iliaca depending on local practice and mobilisation goals
Opioids: PRN short course; avoid long-acting in frail/OSA; add antiemetic and laxatives
Non-pharmacological: ice, physiotherapy coordination, sleep hygiene; address anxiety/delirium risk

Intraoperatively, the patient becomes suddenly hypotensive and desaturates at the time of cement insertion. What is your differential and immediate management?

They are testing crisis management, prioritisation, and BCIS recognition.

Differential: BCIS, anaphylaxis, haemorrhage, myocardial ischaemia/arrhythmia, tension pneumothorax (rare), air embolism, high spinal (if neuraxial)
Immediate actions: call for help; 100% O2; check airway/ventilation; increase monitoring frequency; ask surgeon to pause/pack wound
Treat haemodynamics: vasopressor boluses then infusion; consider adrenaline if severe with RV failure physiology; cautious fluid bolus; obtain ABG
Look for clues: fall in ETCO2 suggests embolic event; wheeze/rash suggests anaphylaxis; rising airway pressures suggests bronchospasm/pneumothorax
Escalation: arterial line, echo if available, ICU/HDU post-op; document event and counsel patient

What are the anaesthetic implications of lateral positioning for THR?

Expect airway, ventilation, access, and pressure injury points.

Airway: secure fixation of ETT/SGA; limited access once draped; bite block if needed; plan for emergency turning supine
Ventilation/perfusion: dependent lung better perfused; ensure adequate ventilation; monitor oxygenation closely in COPD/obesity
Circulation: venous return may change; avoid compression of IVC; ensure no kinking of lines
Pressure/nerve injury: axillary roll, protect brachial plexus, pad peroneal nerve, check eyes/ears; avoid shoulder traction
Access: ensure IV lines and monitoring visible/secure; consider arterial line on non-dependent side for waveform reliability

Discuss thromboprophylaxis for THR and how it interacts with neuraxial anaesthesia.

They want safe timing and coordination with local policy.

THR is high VTE risk: use mechanical prophylaxis and pharmacological prophylaxis per local orthopaedic pathway
Neuraxial safety: ensure appropriate interval between last anticoagulant dose and spinal; time first postoperative dose after neuraxial puncture per guideline; document timing clearly
If indwelling neuraxial catheter (less common for THR): strict rules for dosing and catheter removal timing; monitor for neurological symptoms
Red flag: new back pain, motor weakness, sensory changes, bladder/bowel dysfunction → urgent evaluation for neuraxial haematoma

How would your anaesthetic plan change for revision hip arthroplasty?

Revision = longer, bloodier, higher physiological stress.

Higher blood loss: crossmatch, large-bore access, consider arterial line, cell salvage, TXA; plan transfusion thresholds and calcium monitoring if massive transfusion
Longer duration: GA more likely; consider combined neuraxial for analgesia if anticoagulation permits
Higher infection/loosening risk: antibiotics on time; consider sepsis risk if infected revision (source control, haemodynamic monitoring)
Higher BCIS/embolism risk if cement used or canal manipulation extensive: enhanced vigilance and monitoring

What are the common postoperative complications after THR, and how would you detect and manage them on the ward/PACU?

Think ABCDE + common orthopaedic complications.

Respiratory: hypoxia (atelectasis, PE, opioid effect) → oxygen, analgesia optimisation, mobilisation, investigate PE if suspected
Cardiovascular: hypotension (bleeding, vasodilation, MI, sepsis) → assess volume status, Hb, ECG/troponin if indicated; treat cause
Bleeding/anaemia: check drain output/wound, Hb; transfuse if symptomatic/threshold per patient factors
Delirium: screen (4AT), treat pain/hypoxia/infection, avoid deliriogenic drugs, ensure orientation and sleep
VTE: calf swelling, chest pain, desaturation; follow diagnostic pathway and anticoagulate when safe
Urinary retention post-spinal/opioids: bladder scan and catheterise per protocol