import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: Exits pelvis inferior to piriformis, runs posterior to hip joint 2-3cm medial to greater trochanter tip, may be scarred to posterior tissues in revision, altered position if leg length changed previously. **Protection**: Identify early at inferior border piriformis if anatomy recognizable, protect throughout with retractors under direct vision, keep hip flexed to relax nerve, gentle dissection through scar tissue, avoid overlengthening >4cm (nerve cannot stretch >6%), palpate after final reduction to ensure no tension. **Location**: Exits greater sciatic notch superior to piriformis, runs 25-40mm proximal to greater trochanter tip between gluteus medius and minimus layers, at risk during proximal gluteus dissection and retractor placement. **Protection**: Limit superior dissection to <4cm above trochanter tip, place superior Hohmann retractors under direct vision above acetabular rim (not into gluteal muscle), avoid aggressive superior retraction, use self-retaining retractors with care. **Location**: Runs 30-50mm medial and anterior to acetabulum along iliopsoas muscle, femoral nerve lateral and artery/vein medial, at risk during anterior capsular release, anterior acetabular dissection, or anterior retractor placement. **Protection**: Place anterior retractors carefully under direct vision over anterior acetabular rim (not deep to iliopsoas), avoid aggressive anterior dissection, gentle capsular release, be aware of distorted anatomy from bone loss or superior migration. **Location**: Run along pelvic brim 20-30mm from anterosuperior acetabular rim, 15-20mm from posterosuperior rim (intrapelvic surface), closer if bone loss present with superior/medial migration. **Protection**: Acetabular screw safe zones - posteroinferior (3-5 o'clock right hip, 7-9 o'clock left hip) below transverse acetabular ligament, posterosuperior (10-11 o'clock right hip, 1-2 o'clock left hip) directed posteriorly. Avoid anterosuperior quadrant. Limit screw length to 20-25mm. Direct osteotomes along component rim during extraction (not through intrapelvic cortex). **Location**: Runs through obturator foramen 10-20mm inferior and medial to acetabulum, emerges into medial thigh, at risk during medial wall perforation or inferomedial screw placement. **Protection**: Avoid screws directed inferiorly or medially (especially if medial wall deficient), recognize medial wall perforation during reaming (sudden loss of resistance), use acetabular protrusio rings carefully, ensure screws in safe zones only. ## Primary Indications **Aseptic Loosening (30-40% of Revisions)** - Progressive pain with activity (start pain, groin pain, thigh pain) - Radiographic loosening criteria: progressive radiolucent lines >2mm, component migration >5mm, subsidence, osteolysis, change in position on serial radiographs - Symptomatic with functional limitation despite conservative management - Risk of impending fracture from progressive bone loss **Periprosthetic Joint Infection (15-20%)** - MSIS (Musculoskeletal Infection Society) criteria for diagnosis - Major criteria: 2 positive cultures of same organism, sinus tract communicating with joint - Minor criteria: elevated ESR (>30mm/hr) or CRP (>10mg/L), elevated synovial WBC (>3000) or PMN (>80%), positive alpha-defensin, single positive culture - Definite infection: 1 major criterion OR 4/6 minor criteria **Recurrent Dislocation (20-25%)** - ≥2 dislocations despite closed reduction and conservative management - Chronic instability with inability to maintain reduction - Failed conservative measures: abduction brace, activity modification, physiotherapy - Identifiable cause requiring surgical correction: component malposition, impingement, soft tissue deficiency **Periprosthetic Fracture (10-15%)** - Vancouver B2 femoral fractures - fracture around stem with stem loose - Vancouver B3 - fracture with poor bone stock - Acetabular fractures with component displacement or column involvement - Cannot achieve stable fixation without component revision **Osteolysis and Wear (10-15%)** - Progressive bone loss from polyethylene or metal wear debris - Expanding osteolytic lesions threatening component stability - Risk of impending pathologic fracture - Symptomatic metallosis (metal-on-metal failures) ## Preoperative Assessment **Infection Workup (Mandatory)** - Serum inflammatory markers: ESR, CRP (elevated in 90% of infections) - Hip aspiration if ESR >30 or CRP >10 or any clinical suspicion - Synovial fluid analysis: cell count/differential (WBC >3000 or PMN >80% highly suggestive), culture and sensitivity (hold antibiotics minimum 2 weeks before aspiration) - Alpha-defensin or leukocyte esterase test if available (high specificity for infection) - False negative aspiration 10-15% - if high clinical suspicion proceed with intraoperative frozen section **Imaging Protocol** - AP pelvis, lateral hip (both hips for comparison) - Judet views (obturator oblique, iliac oblique) for acetabular bone stock assessment - Full-length femur AP/lateral (assess femoral bone loss, stem position, distal canal anatomy) - CT scan with 3D reconstruction for severe bone loss (allows defect quantification, custom implant planning, surgical approach planning) - Metal artifact reduction sequences (MARS) MRI if soft tissue assessment needed **Bone Stock Classification** - Paprosky acetabular: Type I (minimal, intact rim), IIA (superior loss, columns intact), IIB (superior/lateral loss), IIC (medial wall deficiency), IIIA (severe loss 2-3cm migration, Kohler intact), IIIB (Kohler violated, pelvic discontinuity possible) - Paprosky femoral: Type I (minimal metaphyseal loss), II (extensive metaphyseal loss, diaphysis >4cm intact), IIIA (metadiaphyseal loss, >4cm isthmus), IIIB (<4cm isthmus), IV (massive loss, widened canal) - Classification guides implant selection and predicts outcomes **Templating** - Use revision-specific templates (extensively coated stems, jumbo cups, modular systems) - Plan femoral stem type: fully-coated for diaphyseal fixation (Type II/III), modular for bone loss (Type III/IV), tumor prosthesis for massive defects (Type IV) - Plan acetabular reconstruction: standard cup (Type I/IIA), jumbo cup (Type IIB), augments (Type IIC/IIIA), cage/triflange (Type IIIB) - Ensure implants available including extended sizes and backup options **Medical Optimization** - Anemia correction: iron supplementation, EPO if Hb <120g/L (reduces transfusion requirements) - Nutritional optimization: albumin >35g/L, lymphocytes >1.5 (wound healing and infection resistance) - Glycemic control: HbA1c <7% in diabetics (reduces infection risk) - Smoking cessation: minimum 6 weeks preoperatively (improves bone healing and reduces infection) - VTE risk assessment: previous VTE, thrombophilia, malignancy (may need extended prophylaxis) - Cardiac/respiratory optimization: longer procedure with higher physiological stress than primary ## Patient Positioning **Standard Lateral Decubitus** - Same as primary THR - lateral position with operative side up - Pelvic support anteriorly at ASIS and posteriorly at sacrum - Ensure pelvis perpendicular to floor (check with alignment device) - All bony prominences well padded (fibular head, medial/lateral malleoli, contralateral greater trochanter) - Prep and drape widely (mid-thorax to knee) - allows proximal/distal extension if required ## Approach Selection **Posterior Approach (Most Common in Australia)** - Utilize previous posterior incision if present (minimize soft tissue compromise) - If multiple scars present, use most lateral scar (better blood supply lateral than medial) - Extended length typically required: 20-30cm (vs 15-20cm primary) for adequate exposure - Can be extended proximally (for acetabular exposure) and distally (for femoral exposure/ETO) **Alternative Approaches** - Anterolateral/Direct Lateral - if previous approach, utilize same scar - Trochanteric osteotomy (slide or flip) - if superior exposure needed (severe superior migration, protrusio) - Transfemoral approach - rarely used, for severe proximal femoral bone loss requiring complete exposure ## Exposure Technique **Incision and Deep Dissection** - Excise previous scar completely (send for histology - exclude malignancy, confirm scar vs tumor) - Deepening through subcutaneous tissue - expect significant scar tissue (obliterates normal planes) - Blunt dissection to develop tissue planes - may be completely scarred, careful sharp dissection required - Identify anatomical landmarks: greater trochanter (key landmark), gluteus maximus fascia **Posterior Approach Specifics** - Gluteus maximus split in line with fibers (may be scarred and difficult to identify) - Expose short external rotators - may be scarred, attenuated, or completely absent from previous surgery - Tag external rotators with sutures if present and repairable (for later repair enhancing stability) - If rotators non-repairable (common in revision) - plan alternative stability measures (large head, dual mobility, constrained liner) **Capsulotomy** - Capsule often attenuated or absent in revision setting - Incise remaining capsule along previous incision line - Tag capsule if present for potential repair (enhances stability if soft tissue deficient) **Neurovascular Protection** - Sciatic nerve at higher risk in revision (injury rate 1-2% vs 0.5% primary) - May be in abnormal position (if leg length altered), may be scarred to posterior tissues - Identify if anatomy allows (at inferior border piriformis) - gentle dissection to mobilize from scar - Protect throughout: retractors under direct vision, keep hip flexed, limit retraction time ## Extensile Exposures **Extended Trochanteric Osteotomy (ETO) - Indications** - Well-fixed uncemented femoral stem (especially fully-coated) difficult to extract - Well-fixed cemented stem with intact cement mantle - Need to bypass proximal femoral fracture or bone defect - Need to correct femoral component malalignment (excessive anteversion/retroversion) - Facilitates cement removal from femoral canal (wide exposure, better visualization) **ETO Technique (Detailed)** - Mark osteotomy on lateral femur with cautery: proximal at vastus ridge, extends distally to 1-2cm past stem tip - Width: 1/3 femoral circumference (thinner fragments at fracture risk, thicker fragments difficult to reflect) - Perforate lateral cortex at multiple levels with 3.2mm drill (creates stress risers for controlled fracture) - Complete longitudinal cuts anteriorly and posteriorly with oscillating saw - Create controlled anterior fracture by gentle levering (prevents uncontrolled spiral fracture) - Reflect anteriorly as bone-muscle flap - preserve vastus lateralis attachments (maintains blood supply critical for healing) - After stem extraction and revision, reduce ETO fragment anatomically - Fixation: minimum 3 cerclage cables (typically 4-6 cables 1-2cm apart), or plate if fragment comminuted - Protected weight-bearing 6 weeks until radiographic union **Trochanteric Slide Osteotomy** - Alternative to ETO for enhanced acetabular exposure - Sliding trochanter with attached abductors superiorly and posteriorly - Preserves abductor continuity while improving acetabular visualization - Fixed with screws or cables at case end ## Hip Dislocation **Technique Modifications for Revision** - Standard dislocation technique (flexion, adduction, internal rotation for posterior approach) - May be difficult if components well-fixed, heterotopic ossification, soft tissue scarring - DO NOT FORCE - high risk of uncontrolled fracture in osteoporotic bone **If Cannot Dislocate** - Excise heterotopic bone with osteotomes and rongeurs if present (send for pathology - exclude malignancy) - Release anterior capsule and iliopsoas if required (improves flexion) - Consider removing femoral head before dislocation (Universal Femoral Head Remover captures modular head for extraction) - Extended trochanteric osteotomy if femoral exposure inadequate despite soft tissue release **Post-Dislocation** - Fully expose acetabular component - remove soft tissue and bone ingrowth from rim and screw holes - Assess acetabular stability: rotation test with extraction device (stable if does not rotate, loose if rotates easily) - Expose femoral component - clear soft tissue from proximal femur and stem shoulder - Assess for subsidence (compare radiographic stem position to intraoperative position) ## Acetabular Component Extraction **Loose Component Technique** - Insert curved osteotomes between component and bone at 3-4 locations circumferentially - Disrupt remaining soft tissue or fibrous ingrowth - Attach explantation device (Universal Femoral Head Remover adapted for cup, or acetabular-specific extractor) - Apply controlled extraction force with slap hammer or threaded extraction - Should remove without excessive force **Well-Fixed Component Technique** - Thin curved osteotomes at bone-implant interface to disrupt bony ingrowth - Work circumferentially around component - advance gradually (avoid acetabular fracture) - Remove screws if present: appropriate drivers, may need to drill out if bone overgrowth covers heads - Osteotome placement critical: direct along component rim between bone and implant (NOT through intrapelvic cortex) - Once ingrowth disrupted 360°, attach extraction device and apply force - If still difficult, consider cup-in-cup technique (leave well-fixed cup, cement new liner inside if position acceptable) **Post-Extraction Debridement** - Remove all polyethylene debris, metal debris (metallosis), cement if cemented cup - Complete synovectomy if metallosis present (black tissue staining from metal debris) - Use curettes, rongeurs, high-speed burr for stubborn adherent material - Copious irrigation to clear particulate debris **Intrapelvic Structure Injury Risk**: External iliac vessels, ureter, bladder, rectum all at risk during acetabular extraction. Osteotome technique critical - direct along component rim, avoid levering against intrapelvic cortex, incremental advancement. Acetabular fracture 3-5% during extraction - small cracks (<2cm) manageable with screw fixation and proceed, large fractures (>2cm, column involvement) require plate fixation before reconstruction, may need to abandon revision if unstable pattern. ## Femoral Component Extraction **Loose Cemented Stems** - Clear cement from stem-cement interface proximally with osteotomes - Attach extraction device to stem (screw into stem or Universal extractor) - Extract with controlled force (typically removes easily) - Cement removal after stem extraction (separate step described later) **Well-Fixed Cemented Stems** - Create windows in proximal cement mantle with osteotomes or high-speed burr - Insert flexible osteotomes at stem-cement interface to disrupt bond - If difficult, consider ETO for controlled extraction - Cement removal after extraction **Loose Uncemented Stems** - Clear bone ingrowth from proximal stem with osteotomes - Attach extraction device (threaded extractor screws into stem, or slap hammer device) - Extract with controlled force using slap hammer or threaded extractor **Well-Fixed Uncemented Stems** - ETO highly recommended to avoid femoral fracture (uncontrolled fracture rate 20-30% without ETO vs <5% with ETO) - ETO performed first, then stem extraction becomes straightforward - After ETO, stem easily extracted by mobilizing from distal to proximal - Alternative: cortical windowing (rectangular windows in proximal femur to access stem) - higher fracture risk, technically demanding **ETO Decision-Making**: Well-fixed fully-coated stems nearly always require ETO if attempting extraction. Extraction force correlates with coating extent: proximally porous-coated stems sometimes removable (can disrupt proximal ingrowth), fully-coated stems 8-10 inches long have extensive ingrowth making extraction without ETO extremely high fracture risk. If reasonable osteotome dissection does not mobilize stem - STOP and perform ETO rather than forcing (prevents catastrophic uncontrolled fracture). ## Cement Removal (If Cemented Stem) **Systematic Approach - Time Consuming (1-2 hours)** - Proximal cement: osteotomes to create longitudinal radial splits, fracture cement into fragments, remove with rongeurs/curettes - Distal cement plug: locate on preoperative X-rays (measure from lesser trochanter), drill through plug with long drill bit - Use reverse cement hooks and curettes to remove fragments working proximally from plug - High-speed burr for cement adherent to endosteum - CAUTION not to damage bone (increases perforation risk) - Ultrasonic cement removal device for stubborn cement - Copious pulsed lavage irrigation to remove all debris - Inspect with headlight and flexible fiberoptic light (illuminate distal canal, confirm no residual cement) - Flexible reamers to smooth endosteal surface (create bleeding bone bed for biological fixation) **Cortical Perforation 5-10%**: Risk factors - thin cortices, osteoporosis, aggressive burr use. Small perforations (<1cm) bypass with longer stem extending 2+ cortical diameters past perforation. Large perforations (>1cm) require cortical strut allograft or plate fixation before stem insertion. **Femoral Fracture 2-5%**: From weakening cortex during cement removal or extraction force. Prevention - gentle incremental removal, cement-splitting technique (longitudinal osteotomes fracturing cement vs burring through), patience required. ## Acetabular Bone Defect Assessment **Systematic Evaluation** - Expose entire acetabulum circumferentially with Hohmann retractors (anterior, posterior, superior) - Remove ALL fibrous tissue and soft tissue (visualize true bone anatomy) - Palpate bone stock systematically: - Anterior column (typically preserved) - Posterior column (typically preserved unless posterior wall fracture) - Superior rim (load-bearing area - often deficient from superior migration and wear) - Medial wall (may be deficient from medial migration or osteolysis) - Inferior rim (transverse acetabular ligament - landmarks anatomical inferior position) **Paprosky Classification - Acetabular** - **Type I**: Intact rim, minimal bone lysis, <50% host bone contact possible but stable fixation achievable - **Type IIA**: Intact columns, superior bone loss, 50% host bone contact possible, <2cm superior migration - **Type IIB**: Superior/lateral bone loss with some medial migration, transverse acetabular ligament (TAL) preserved, columns intact - **Type IIC**: Medial wall deficiency with medial migration, columns intact, TAL may be compromised - **Type IIIA**: Severe bone loss 2-3cm superior/lateral migration, Kohler line intact (medial wall present), may have ischial lysis - **Type IIIB**: Severe bone loss with superior/medial migration, Kohler line violated (medial wall absent), pelvic discontinuity possible **Pelvic Discontinuity Assessment** - Palpate for motion between superior and inferior hemipelvis (manually stress pelvis) - Radiographic signs: step at ilioischial line, independent movement of superior/inferior hemipelvis on stress views - CT scan helpful if suspected (3D reconstruction shows discontinuity) ## Acetabular Reconstruction by Paprosky Type **Type I / IIA - Standard Uncemented Cup** - Ream to bleeding bone with hemisphere reamers (sequential 2mm increments) - Achieve 70% host bone contact (anteroinferior and posteroinferior bone typically preserved) - Insert hemispheric cup 1-2mm larger than final reamer (press-fit) - Position within Lewinnek safe zone (40±10° abduction, 15±10° anteversion) - Supplement with 2-3 screws in safe zones if stability suboptimal - Outcomes: 95% survival at 10 years **Type IIB - Jumbo Cup / High Hip Center** - Jumbo cup (4-6mm oversized) bridges superior defect, gains fixation on remaining intact bone - High hip center acceptable if <2cm superior migration (excessive migration increases joint reactive force) - OR superior metal augment (tantalum/titanium wedge) fixed to ilium with screws, cup contacts augment superiorly **Type IIC - Medial Wall Reconstruction** - Restore medial wall with particulate bone graft (morselized allograft) - Contain graft with mesh (prevents extrusion into pelvis) - Ream to create bleeding bone surface - Insert standard cup with lateral coverage on host bone - Graft remodels and incorporates providing biological fixation **Type IIIA - Severe Loss, Kohler Intact** - Option 1: Jumbo cup with superior metal augment (augment fixed to ilium, cup contacts augment + remaining host bone) - Option 2: Trabecular Metal (TM) augments - highly porous tantalum contoured to fill defect, fixed with screws, biologicalizes defect, cup fixed to augment and host bone - Outcomes: 85-90% survival at 10 years **Type IIIB - Severe Loss, Kohler Violated** - Option 1: Cup-cage construct - antiprotrusio cage spanning ilium to ischium (structural support), fixed with multiple screws (iliac 2-3, ischial 1-2), cup cemented within cage in correct orientation - Option 2: Custom triflange implant - patient-specific 3D-printed component with flanges to ilium/ischium/pubis, allows biological fixation, 5-year survival 85-90% - Outcomes: 80-85% survival at 10 years **Pelvic Discontinuity** - Restore pelvic ring integrity: posterior column plate if possible - Cup-cage construct bridging discontinuity - Dual mobility bearing within cage (reduce dislocation risk in complex reconstruction) ## Femoral Bone Defect Assessment **Systematic Evaluation** - Expose entire proximal femur - Palpate cortical bone circumferentially (assess integrity) - Identify segmental vs cavitary defects - Assess proximal bone quality (metaphyseal fixation possible vs requires diaphyseal fixation) - Measure intact diaphyseal bone length (from lesser trochanter distally) **Paprosky Classification - Femoral** - **Type I**: Minimal metaphyseal bone loss, intact diaphysis, good cancellous bone in metaphysis - **Type II**: Extensive metaphyseal bone loss (cancellous bone absent, cortices intact), intact diaphysis >4cm - **Type IIIA**: Severe metadiaphyseal bone loss, >4cm intact diaphyseal bone available for fixation - **Type IIIB**: Severe bone loss with <4cm intact diaphyseal bone, canal widened - **Type IV**: Extensive metadiaphyseal bone loss, widened canal, little cortical support ## Femoral Reconstruction by Paprosky Type **Type I - Standard Uncemented Stem** - Prepare canal with cylindrical/tapered reamers to bleeding bone - Insert standard uncemented stem (press-fit in metaphysis and proximal diaphysis) - Achieve 4-6cm diaphyseal engagement - Modular stems allow offset/version adjustment - Outcomes: 95% survival at 10 years **Type II - Extensively Coated Cylindrical Stem** - Bypass deficient metaphysis, achieve diaphyseal fixation - Fully-coated stem 8-10 inches long with porous ingrowth surface - Ream diaphysis with flexible reamers to bleeding bone - Insert with 4-6cm diaphyseal contact (scratch-fit) - Minimal metaphyseal contact acceptable - OR modular tapered stem (metaphyseal + diaphyseal components, independent version/offset adjustment) - Outcomes: 90-95% survival at 10 years **Type IIIA - Long Extensively Coated Stem + Struts** - Long stem 10-12 inches bypassing all defects, engaging 4-6cm intact diaphysis distally - Segmental cortical defects: onlay cortical strut allografts (2-4 struts circumferentially) - Strut fixation: cerclage cables proximally and distally, minimum 2 cortical diameter overlap (ideally 8-10cm) - Cavitary defects: particulate bone graft impaction - Modular stem allows version/offset adjustment - Outcomes: 85-90% survival at 10 years **Type IIIB - Impaction Grafting / Modular Stem** - Option 1: Impaction bone grafting (Ling technique) - morselized allograft impacted creating neo-cortex, cemented polished stem, graft incorporates restoring bone stock - Option 2: Modular extensively-coated tapered stem maximizing diaphyseal contact despite short (<4cm) fixation length - Outcomes: 75-85% survival at 10 years **Type IV - Proximal Femoral Replacement / Allograft-Prosthesis Composite** - Option 1: Megaprosthesis (tumor implant) replacing proximal femur to mid-diaphysis, cemented distal fixation, immediate stability, high dislocation rate requires constrained liner/dual mobility - Option 2: Allograft-prosthesis composite - structural allograft for proximal femur, stem cemented into allograft, allograft-host junction fixed with plate, restores bone stock, nonunion risk 10-20% - Outcomes: 70-80% survival at 10 years ## Trial Reduction and Stability Assessment **Systematic Stability Testing** - Insert trial components (liner and femoral head with multiple neck length options) - Reduce hip and assess stability through full range of motion: - Flexion 110° with internal rotation 70-90° (tests posterior stability - highest risk position for posterior dislocation) - Extension 30° with external rotation 45° (tests anterior stability) - Should be stable without excessive force required for dislocation **Soft Tissue Tension Assessment** - Shuck test: translate femoral head within acetabulum - 5-10mm translation = appropriate tension - >15mm translation = overlengthening or excessive laxity - Unable to translate = excessive tightness (risk of joint stiffness, femoral fracture from impaction forces) **Leg Length and Offset Assessment** - Multiple measurement methods: - Offset guide comparing to contralateral hip - Measure from fixed pelvic landmark (ASIS) to fixed femoral landmark (lesser trochanter, fibular head) - Clinical assessment (heel height comparison, symmetry) - Offset restoration critical for abductor function (each 5mm offset loss reduces abductor moment arm 15%) **Impingement Testing** - Test extremes of motion looking for prosthetic or bony impingement - Should achieve functional arc without impingement: flexion 110°, extension 30°, abduction 45°, adduction 30° **Sciatic Nerve Tension Check** - Palpate sciatic nerve to ensure no tension - Excessive lengthening >4cm risks nerve injury (nerve cannot stretch >6% before injury) ## Stability Optimization Strategies **If Stability Inadequate with Trials** - Increase femoral head size: 32mm → 36mm → 40mm (larger head increases jump distance and range before impingement) - Dual mobility if large head insufficient: effective head diameter 52-56mm, reduces re-dislocation from 15-20% to 1-3% - Increase neck length (but avoid overlengthening >10mm which paradoxically increases dislocation by abductor laxity) - Verify component positions (if malpositioned, revise to correct position before finalizing) - Constrained liner as last resort if soft tissues irreparable and dual mobility insufficient (mechanical constraint with locking ring, 5-10% failure rate) **Clinical Pearl - Cannot Judge Stability from Radiographs** - MUST perform intraoperative stability testing - If unstable with trials, DO NOT implant final components hoping it will be stable - Address instability before finalizing (change head size, dual mobility, constrained liner, revise component position) ## Final Component Insertion **Acetabular Component** - Clean acetabular bone bed with pulsed lavage and dry - Insert definitive component matching trial (size, position, orientation) - Uncemented cups: use introducer aligned at planned abduction/anteversion, seat with mallet strikes starting inferiorly working circumferentially - Assess for 360° rim contact and stability to rotation - Augment reconstruction: ensure augment-host bone interface stable, augment-cup interface stable - Cage constructs: ensure cage stable with screws to ilium/ischium, cement cup within cage in correct orientation - Insert liner ensuring locking mechanism engaged (check visually and attempt to lever out) **Femoral Component** - Clean femoral canal with pulsed lavage - Uncemented stems: insert with introducer at planned version matching trial, advance to templated depth, impact with mallet ensuring full seating, assess axial and rotational stability - Cemented stems: insert distal plug, retrograde cement fill with gun, pressurize cement, insert stem during dough phase maintaining version/depth, hold stable 8-10 minutes during polymerization - Modular stems: assemble metaphyseal and diaphyseal components ensuring modular taper fully engaged (clean and dry tapers before assembly) **Extended Trochanteric Osteotomy Fixation** - Reduce ETO fragment to femur anatomically - Ensure fragment not interfering with femoral component - Fix with 3-4 cerclage cables or plate - Cables placed 1-2cm apart, adequate tension but avoid excessive (cracks fragment) - Plate fixation if fragment large or comminuted (better stability, more soft tissue stripping) **Cortical Strut Allograft Fixation** - Position struts bridging segmental defects - Ensure strut-host bone overlap 2+ cortical diameters proximally and distally (ideally 8-10cm) - Fix with cerclage cables (3-4 per strut) or bicortical screws if cortex adequate - Rigid fixation preventing motion at allograft-host interface **Final Head Insertion and Reduction** - Clean and dry stem taper and femoral head taper - Impact head with mallet ensuring fully seated - Reduce hip with definitive components - Recheck stability (should match trial stability) - Recheck leg length and offset ## Soft Tissue Repair and Closure **Irrigation** - Copious irrigation with 6-9 liters saline (more than primary due to longer operative time, greater contamination risk) **Soft Tissue Repair** - Short external rotators to greater trochanter through bone tunnels if present and repairable - If rotators absent/non-repairable (common in revision), rely on implant stability (large head, dual mobility, constrained liner) - Conjoint tendon of gluteus medius/minimus if detached during exposure - Repair gluteus maximus fascia with interrupted absorbable sutures **Drain Placement** - Deep drain more commonly used in revision than primary (larger dead space, higher hematoma risk) - Expected output 200-600mL over 24-48h - Remove when output <50mL/8h (typically 24-48h) **Layered Closure** - Subcutaneous fat and fascia lata with absorbable sutures (1-0 Vicryl) - Skin with subcuticular absorbable suture or staples - Waterproof dressing and abduction pillow ## Postoperative Protocol **Weight-Bearing** - TDWB (touch-down 10-20kg) for 6 weeks if ETO or cortical struts used - Advance to WBAT at 6 weeks if radiographic healing evidence - Full weight-bearing at 12 weeks once solid union confirmed - WBAT immediately if standard uncemented reconstruction without ETO/struts **Hip Precautions - Extended Duration** - 12 weeks minimum (vs 6 weeks in primary) due to soft tissue deficiency - No flexion >90°, no adduction past midline, no internal rotation in flexion - Abduction pillow between legs for 6 weeks - Consider abduction brace if very high instability risk **VTE Prophylaxis** - LMWH (enoxaparin 40mg SC daily) OR DOAC (rivaroxaban 10mg daily, apixaban 2.5mg BD) - Start 12-24h postoperatively, continue 35 days - Mechanical prophylaxis: TED stockings and IPC until mobile **Mobilization** - POD1-2 with physiotherapy (later than primary due to pain and extent) - Gait training with walking aids - Abductor strengthening critical (many have preoperative weakness) **Radiographic Surveillance** - 6 weeks: component position, ETO/strut healing, early loosening signs - 3 months: ETO/strut union - 6 months, 1 year, then annually per AOANJRR protocol ## References 1. Paprosky WG, Perona PG, Lawrence JM. Acetabular defect classification and surgical reconstruction in revision arthroplasty: a 6-year follow-up evaluation. *J Arthroplasty*. 1994;9(1):33-44. doi:10.1016/0883-5403(94)90135-x - Original description of Paprosky acetabular classification system correlating bone defect patterns with reconstruction strategies and outcomes. 2. Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). *Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report*. Adelaide: AOA; 2023. - Comprehensive Australian registry data showing revision THR cumulative revision rate 14.8% at 10 years, failure modes, and implant-specific performance. 3. Della Valle CJ, Paprosky WG. The femur in revision total hip arthroplasty evaluation and classification. *Clin Orthop Relat Res*. 2004;(420):55-62. doi:10.1097/00003086-200403000-00008 - Paprosky femoral classification system correlating metaphyseal and diaphyseal bone loss patterns with reconstruction options. 4. Younger TI, Bradford MS, Magnus RE, Paprosky WG. Extended proximal femoral osteotomy: a new technique for femoral revision arthroplasty. *J Arthroplasty*. 1995;10(3):329-338. doi:10.1016/s0883-5403(05)80182-2 - Original description of extended trochanteric osteotomy technique, indications, fixation methods, and outcomes showing union rate >95%. 5. Parvizi J, Tan TL, Goswami K, et al. The 2018 definition of periprosthetic hip and knee infection: an evidence-based and validated criteria. *J Arthroplasty*. 2018;33(5):1309-1314. doi:10.1016/j.arth.2018.02.078 - Updated Musculoskeletal Infection Society (MSIS) criteria for diagnosing periprosthetic joint infection with major and minor criteria. 6. Sporer SM, Paprosky WG. Acetabular revision using a trabecular metal acetabular component for severe acetabular bone loss associated with a pelvic discontinuity. *J Arthroplasty*. 2006;21(6 Suppl 2):87-90. doi:10.1016/j.arth.2006.05.015 - Trabecular metal augment reconstruction for Paprosky Type IIIA/IIIB defects showing 85-90% survival at medium-term follow-up. 7. Gill TJ, Sledge JB, Müller ME. The Bürch-Schneider anti-protrusio cage in revision total hip arthroplasty: indications, principles and long-term results. *J Bone Joint Surg Br*. 1998;80(6):946-953. doi:10.1302/0301-620x.80b6.8414 - Cup-cage construct technique and outcomes for severe acetabular bone loss (Paprosky Type IIIB) with 80-85% survival at 10 years. 8. Weeden SH, Paprosky WG. Minimal 11-year follow-up of extensively porous-coated stems in femoral revision total hip arthroplasty. *J Arthroplasty*. 2002;17(4 Suppl 1):134-137. doi:10.1054/arth.2002.32461 - Long-term outcomes of extensively porous-coated cylindrical stems for Paprosky Type II/IIIA femoral defects showing 90-95% survival with 4-6cm diaphyseal fixation. 9. Mortazavi SMJ, Lewallen DG, Melton LJ, Kremers HM, Berry DJ. Periprosthetic femoral fractures following total hip arthroplasty: an analysis of outcomes based on fracture pattern and treatment. *J Arthroplasty*. 2016;31(1):193-199. doi:10.1016/j.arth.2015.07.037 - Vancouver classification-based management of periprosthetic femoral fractures with outcomes by fracture type and treatment strategy. 10. Lewinnek GE, Lewis JL, Tarr R, Compere CL, Zimmerman JR. Dislocations after total hip-replacement arthroplasties. *J Bone Joint Surg Am*. 1978;60(2):217-220. - Classic paper defining Lewinnek safe zone for acetabular component positioning (40±10° abduction, 15±10° anteversion) to minimize dislocation risk.

Revision Total Hip Replacement

Revision Total Hip Replacement