import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: 2-3cm posterior and inferior to posterior acetabular rim, may be displaced medially by subsided stem or encased in scar tissue **Protection**: Early identification with blunt dissection, finger protection throughout, gentle retraction with Hohmann or nerve retractor, avoid limb lengthening over 4cm, 2-5% injury rate in revision vs 0.2% in primary **Location**: 5cm superior to greater trochanter, exits greater sciatic notch above piriformis muscle insertion **Protection**: Avoid dissection superior to piriformis tendon, stay anterior to greater sciatic notch, injury causes abductor denervation and Trendelenburg gait **Location**: Anterior to hip joint, medial to proximal femur along iliopsoas **Protection**: Catastrophic bleeding if perforated during anterior reaming or cement removal, control reamer depth, maintain finger in anterior joint to monitor breakthrough, immediate vascular consultation if breach **Location**: Greater trochanter is insertion of gluteus medius (lateral/superior facet) and gluteus minimus (anterior facet) **Protection**: If ETO performed, requires stable cable fixation with 3+ cables for union, protected weight-bearing 6-8 weeks, failure causes Trendelenburg gait, non-union rate 5-10% **Location**: Thin medial wall of acetabulum separating joint from intrapelvic structures (iliac vessels, obturator neurovascular bundle) **Protection**: At risk during aggressive acetabular debridement or reaming, recognize pre-op on X-ray/CT (Kohler's line, teardrop), gentle technique medially, immediate laparotomy if intrapelvic breach with bleeding ## MSIS Diagnostic Criteria for PJI **Major Criteria** (need 2 or more): 1. **Sinus tract** communicating with prosthesis 2. **Synovial fluid analysis**: WBC over 3000 cells/µL OR PMN percentage over 80% 3. **Serum markers**: ESR over 30 mm/h AND CRP over 10 mg/L 4. **Positive cultures**: 2 or more separate samples with same organism 5. **Histology**: Over 5 polymorphonuclear leukocytes per high-power field (400×) in 5 separate fields **Minor Criteria** (supportive but not diagnostic alone): - Single positive culture - Elevated synovial CRP over 10 mg/L - Elevated alpha-defensin - Elevated synovial leukocyte esterase - Positive synovial C6 peptide **Exam Key**: MSIS criteria revised in 2018 - need 2 or more major criteria OR score-based system using minor criteria. Sinus tract is pathognomonic (definite infection). Tissue culture more sensitive than fluid culture (94% vs 70% for multiple samples). Hold antibiotics 2 weeks pre-op to maximize culture yield from 60% to 80%. ## Antibiotic Holiday Protocol **Rationale**: Antibiotics suppress bacteria but don't eradicate biofilm - creates false negative cultures **Stage 1**: Stop antibiotics 2 weeks before surgery - Improves culture yield from 60% to 80% - Allows identification of causative organism - Risk: systemic sepsis if highly virulent organism (monitor clinically) **Stage 2**: Stop antibiotics 2 weeks before reimplantation - Unmasks persistent infection - Improves aspiration sensitivity from 40% to 75% - If aspiration positive after holiday: abort Stage 2, repeat debridement **Exam Key**: Antibiotic holiday critical at BOTH stages. Unknown organism reduces two-stage success by 20% (unable to target antibiotics). False reassurance from antibiotics masking persistent infection at Stage 2 leads to 50% failure rate. ## Imaging Assessment for Bone Loss **Radiographs**: - AP pelvis and lateral hip - Judet views (obturator oblique, iliac oblique) for acetabular assessment - Full-length femur AP/lateral if previous fracture or extensive osteolysis **CT Scan**: - Assess acetabular bone stock (Paprosky classification) - Identify pelvic discontinuity - Measure bone defects for reconstruction planning - Plan custom implants if needed (triflange) **Paprosky Acetabular Classification**: - **Type I**: Intact rim, minimal migration, intact teardrop/Kohler's line - **Type IIA**: Superior-medial wear, intact rim, Kohler's line intact - **Type IIB**: Superior migration under 3cm, medial wall intact, ischial lysis - **Type IIC**: Medial wear, Kohler's line disrupted, intact columns - **Type IIIA**: Severe superior migration over 3cm, less than 50% host bone contact - **Type IIIB**: Pelvic discontinuity, severe medial/global deficiency **Paprosky Femoral Classification**: - **Type I**: Minimal metaphyseal bone loss, intact diaphysis - **Type II**: Extensive metaphyseal damage, intact diaphysis - **Type IIIA**: Metaphyseal damage, 4cm or more diaphyseal contact available - **Type IIIB**: Extensive metaphyseal and diaphyseal damage, under 4cm contact - **Type IV**: Extensive damage, nonsupportive isthmus, scarce diaphyseal contact - Order antibiotic cement components (vancomycin 4g vials, tobramycin 2.4g) - Cell saver CONTRAINDICATED in infection (disseminates bacteria) - Consent for ETO, nerve injury, recurrent infection, salvage procedures (Girdlestone, arthrodesis, amputation) - Ensure availability of revision implants: augments, cages, modular stems, dual mobility - Infectious Disease consultation for antibiotic selection ## Patient Positioning and Draping **Lateral Decubitus Position**: - Affected side up - Pelvis perpendicular to floor (confirmed with positioning rod or fluoroscopy) - Anterior pelvic support at ASIS - Posterior support at sacrum - Bean bag or dedicated pelvic positioner - All bony prominences padded (fibular head, medial malleolus, dependent shoulder) - Axillary roll under dependent axilla (prevent brachial plexus injury) **Stability Check**: - Table tilt test to confirm secure positioning - Patient must not shift during reduction maneuvers - Pelvic obliquity causes cup malposition (anteversion/inclination errors) **Draping**: - Prepare entire leg from iliac crest to toes - Wide circumferential prep for extensile exposure if needed - Mark greater trochanter, PSIS, femoral shaft **Technical Tip**: Pelvis perpendicular to floor is CRITICAL - obliquity causes systematic cup malposition. Use positioning rod or fluoroscopy to confirm. Anterior support prevents patient rolling forward during acetabular exposure/reaming. Wide prep allows extension for ETO or challenging exposure. ## Posterior Approach and Exposure **Incision**: - Use previous posterior scar (typically 8-15cm) - Extend proximally toward PSIS or distally 5cm beyond GT if needed - Anticipate indurated scar tissue from previous surgery and infection **Dissection**: - Deepen through subcutaneous tissue (may be fibrous) - Incise fascia lata in line with femur - Split gluteus maximus in line of fibers (internervous plane between superior and inferior gluteal nerves) **CRITICAL**: Early sciatic nerve identification - Blunt dissection with finger palpation - Nerve may be adherent in scar tissue - May be displaced medially by subsided stem - Protect throughout with finger or Hohmann retractor - 2-5% injury rate in revision vs 0.2% in primary THA **Capsule and Short External Rotators**: - Usually scarred and thickened - Release from posterior trochanter to femoral neck insertion - Excise thickened posterior capsule completely (biofilm harbor) - Tag for later repair **Hip Dislocation**: Posterior with flexion, adduction, internal rotation - Sciatic nerve HIGHEST RISK in revision THA - Identify early with blunt dissection - Use finger protection throughout - Avoid limb lengthening over 4cm (nerve stretch injury) - Superior gluteal nerve: avoid dissection above piriformis - Femoral nerve anterior: at risk with anterior reaming ## Tissue Sampling Protocol **BEFORE any debridement** (critical for uncontaminated cultures): - Obtain **5-6 tissue samples** from different sites: 1. Capsule/pseudocapsule 2. Femoral interface membrane 3. Acetabular interface membrane 4. Femoral bone 5. Acetabular bone 6. Soft tissue from different quadrant **Technique**: - Use separate instruments for each sample - Avoid superficial contamination - Send in separate sterile containers **Laboratory**: - Aerobic culture (14-day hold) - Anaerobic culture (14-day hold) - Fungal culture if immunosuppressed - Hold 14 days for slow-growing organisms (Cutibacterium/Propionibacterium) - Histology: 1-2 samples for frozen and permanent sections **Evidence**: Multiple tissue samples CRUCIAL - single culture 70% sensitivity vs 94% with multiple samples. Need 2 or more positive cultures with same organism for MSIS diagnosis. Tissue culture more sensitive than fluid. Cutibacterium causes 10% of PJI and requires extended culture (14 days). ## Component Removal and ETO **Acetabular Cup Removal**: - Curved osteotomes around cup-bone interface circumferentially - Start at superior dome, work around 360 degrees - Leverage out with broad osteotome - Preserve bone stock **Femoral Stem Removal**: **If cemented or well-fixed**: Perform **EXTENDED TROCHANTERIC OSTEOTOMY** **ETO Technique**: 1. Mark anterolateral femur, 8-10cm length 2. One-third circumference (preserve posterior 2/3) 3. Preserve vastus lateralis attachment posteriorly (blood supply from lateral circumflex femoral artery) 4. Three cuts with oscillating saw: - Anterior vertical cut - Distal horizontal cut - Posterior vertical-oblique cut (connects to distal) 5. Hinge open like a book with abductors attached 6. Stem now accessible for removal **Cement Removal**: - Ultrasonic cement removal system (UCRS) preferred - OR high-speed burr with long thin carbide bits - Remove ALL cement down to canal - Work systematically from proximal to distal - Finger in anterior joint to detect perforation - Headlamp and loupes for visualization **Technical Tip**: ETO essential for complete cement removal - attempting without ETO has 30% perforation risk. ETO allows direct visualization and removal of all cement (biofilm harbor). Technique: preserve vastus lateralis posteriorly (blood supply), 8-10cm length adequate for most cases, 90% union rate with proper fixation (3+ cables). ## Radical Debridement **Principles**: Aggressive debridement is KEY to success - inadequate debridement causes 50% of recurrent infections **Soft Tissue**: - Complete synovectomy (remove ALL synovium) - Excise entire interface membrane (biofilm harbor) - Remove all PMMA debris, cement fragments - Remove all metal debris, polyethylene particles - Excise any sinus tract completely to skin **Bone**: - Debride non-viable bone (grey, sclerotic, avascular) - High-speed burr for sclerotic areas - Curettes for membrane - Rongeurs for osteolytic bone - Ream acetabulum to bleeding bone - Ream femoral canal to bleeding bone - Aim for "Paprika sign" (healthy bleeding bone bed) **Balance**: Adequate debridement vs preserving bone stock for reimplantation - Inadequate debridement of biofilm causes persistent infection (50% recurrence) - Excessive bone loss compromises reimplantation (may need structural graft, cage, or salvage) - Femoral or acetabular perforation during aggressive debridement - Quadrilateral plate breach during acetabular debridement (intrapelvic injury) ## High-Volume Irrigation and Decontamination **Irrigation Protocol**: - Minimum **9 litres** normal saline (some institutions use 12-15L) - Body temperature saline (37°C) - High pressure pulse lavage initially (mechanical debridement) - Then low pressure (avoid driving bacteria into bone) - Irrigate all recesses (acetabulum, femoral canal, soft tissue pockets) **NO additives**: No antibiotics, Betadine, chlorhexidine, hydrogen peroxide - Cytotoxic to osteoblasts - Impairs bone healing - Mechanical removal more effective than chemical **CHANGE ALL**: - After lavage: change gloves, gowns, instruments - Re-drape if possible - Use FRESH IMPLANT SETS for spacer insertion - Simulates "new operation" - reduces bacterial load **Evidence**: Minimum 9L irrigation reduces bacterial load 100-fold. Mechanical removal more important than additives. CHANGE ALL after lavage reduces bacterial load further - acts like starting fresh case. Antiseptic additives (Betadine, chlorhexidine, H2O2) are cytotoxic to osteoblasts and impair bone healing at reimplantation. ## Antibiotic Spacer Fabrication and Insertion **Spacer Type**: **ARTICULATING** preferred over static **Advantages**: - Maintains limb length and offset - Prevents soft tissue contracture - Preserves ROM - Allows weight-bearing mobilization (WBAT) - Easier Stage 2 reimplantation - Preserves bone (avoids stress shielding) - **Similar infection control rate to static** **Disadvantages**: - 13-15% dislocation rate (vs 5% static) - acceptable - 5-10% fracture rate (usually late, over 3 months) - More technically complex **Static Spacer**: Reserved for severe instability or abductor deficiency **Options for Articulating Spacer**: 1. **Preformed commercial**: PROSTALAC, Spacer-G (expensive, good quality) 2. **Hand-made**: Femoral head mold for acetabular component, stem mold for femoral, 36-40mm metal head on femoral component **HANSSEN HIGH-DOSE ANTIBIOTIC CEMENT PROTOCOL**: - **4g vancomycin powder** + **2.4g tobramycin powder** per **40g cement** - This is **3× standard dosing** - Use Palacos or Simplex cement (high fatigue strength) - Hand-mix or vacuum-mix **Rationale**: - Achieves local concentration 200× MIC - Bactericidal against biofilm bacteria - Minimal systemic absorption (low toxicity) - Vancomycin covers Gram-positive (including MRSA) - Tobramycin covers Gram-negative **Organism-Specific Antibiotics** (if known): - VRE: Daptomycin 4g per 40g cement - Pseudomonas: Ceftazidime or tobramycin - Fungi: Voriconazole or amphotericin **Insertion Technique**: 1. Insert acetabular spacer first (mushroom shape, 2-3mm larger than native) 2. Insert femoral component with metal head 3. Reduce hip 4. Ensure spacer is **STABLE but retrievable** 5. Avoid excess cement keying into canal (makes removal difficult) 6. Trial stability - should resist dislocation but not too tight **High-Yield**: ARTICULATING spacer benefits over static: maintains length/offset, prevents contracture, allows WBAT, easier reimplantation, similar infection control. Dislocation rate 13-15% acceptable. HIGH-DOSE antibiotics (Hanssen): 4g vancomycin + 2.4g tobramycin per 40g cement provides 200× MIC local concentration with low systemic toxicity. ## ETO Repair and Wound Closure **If ETO performed**: 1. Reduce trochanteric fragment anatomically - Greater trochanter should align with femoral shaft contour - Restore normal abductor lever arm 2. Fix with **minimum 3 CERCLAGE CABLES**: - 18-gauge stainless steel or titanium cables - Pass cables around intact femur proximal to osteotomy - Pass cables around intact femur distal to osteotomy - Tighten sequentially to achieve compression - May add vertical cable longitudinally if unstable - Specialized ETO claw plate for severe instability 3. Test stability by pulling on abductors - Must be rigid to permit union - 90% union rate if properly fixed **Soft Tissue Repair**: - Repair posterior capsule remnants - Repair short external rotators to posterior trochanter - Re-establish posterior soft tissue restraint (prevents dislocation) - Close gluteus maximus - Close fascia lata - Subcutaneous absorbable sutures - Skin (staples or subcuticular) **Drains**: Debated - Some avoid in infection setting - Some use closed suction for 24 hours - Need 3 or more cables for union - Must achieve stable compression - Protected weight-bearing until union (6-8 weeks) - Non-union rate 5-10% - Risk factors: infection, inadequate fixation, smoking, non-compliance - Non-union requires ORIF with plate + cables + bone graft if symptomatic ## Stage 1 Postoperative Management **IV Antibiotics**: **6 weeks minimum** (extend to 12 weeks for difficult organisms) **Organism-Specific** (once cultures return): - **MRSA/MSSA**: Vancomycin IV 15mg/kg q12h (MRSA) OR flucloxacillin 2g q6h (if sensitive) - **Gram-negative**: Fluoroquinolone (ciprofloxacin 400mg IV q12h) or 3rd-generation cephalosporin - **Polymicrobial**: Broad spectrum (vancomycin + ceftriaxone or meropenem) - **Fungi**: Amphotericin or echinocandin (caspofungin) **RIFAMPICIN**: **ESSENTIAL for ALL Staphylococcal PJI** - 300-450mg PO twice daily - Start AFTER wound healed (day 5-7) - Excellent biofilm penetration - Bactericidal against slow-growing organisms - **MUST pair** with fusidic acid or fluoroquinolone (prevent resistance) - **NEVER monotherapy** (resistance develops within days) **Monitoring**: - Weekly CRP and ESR - Should trend downward (CRP halves weekly) - If plateau or rise: suspect persistent infection **Mobilization**: - **WBAT** if articulating spacer stable - Hip precautions (avoid flexion over 90°, adduction, internal rotation) - Walker or crutches **Interval Before Stage 2**: - **Minimum 6-8 weeks** from Stage 1 - Some wait 12+ weeks for difficult organisms (fungi, resistant bacteria) - **ANTIBIOTIC HOLIDAY 2 weeks before Stage 2** (critical - unmasks persistent infection) **Protocol**: 6 weeks IV antibiotics standard, extend to 12 weeks if needed. Rifampicin ESSENTIAL for Staph PJI - start AFTER wound healed (skin necrosis risk). Pair with fusidic acid or fluoroquinolone (prevent resistance). Monitor CRP weekly - should drop 50%/week. Antibiotic holiday 2 weeks pre-Stage 2 CRITICAL - unmasks persistent infection, improves aspiration sensitivity from 40% to 75%. ## Criteria for Proceeding to Stage 2 **Essential Requirements**: 1. **Completed antibiotic course**: 6-12 weeks IV antibiotics 2. **Normalized inflammatory markers**: - CRP under 10 mg/L - ESR under 30 mm/h - Trending downward if not normalized 3. **Well-healed wound**: No drainage, no erythema, no tenderness 4. **Patient medically optimized**: Nutritional status, comorbidities controlled 5. **Minimum interval**: 6-8 weeks from Stage 1 (extend to 12+ weeks for difficult organisms) **If Doubt Exists**: **ASPIRATION after 2-week antibiotic holiday**: - Send for cell count, culture (aerobic/anaerobic/fungal) - Synovial WBC over 3000 or PMN over 80% suggests persistent infection - Positive culture = ABORT Stage 2 **Options if Aspiration Positive**: 1. Repeat debridement + new spacer + extended antibiotics 2. Chronic suppression (indefinite oral antibiotics) 3. Salvage procedures (Girdlestone, arthrodesis, amputation) **Decision Point**: Timing Stage 2 requires normalized CRP (under 10), ESR (under 30), minimum 6-8 weeks interval, healed wound. Antibiotic holiday 2 weeks before assessment CRITICAL. If doubt: aspirate after holiday - positive culture means either repeat debridement + new spacer or chronic suppression. Reimplanting with active infection drops success from 85-90% to under 50%. ## Spacer Complications During Interval **Dislocation** (13-15% with articulating): - **Management**: Closed reduction, hip precautions, abduction brace - If recurrent: consider revising to static spacer or expedite Stage 2 - Most occur within first 6 weeks **Spacer Fracture** (5-10%): - Usually late (over 3 months) - **Management**: If late, indicates time for Stage 2 (cement fatigue from normal timeframe) - If early (under 3 months): revise spacer, investigate cause **Persistent Drainage**: - Suggests inadequate debridement - Culture drainage - May need repeat debridement **Medical Deterioration**: - Optimize before Stage 2 - May need prolonged interval - Consider chronic suppression if unfit for surgery - Rising or plateau CRP/ESR despite adequate antibiotics (persistent infection) - Persistent wound drainage (sinus tract, inadequate debridement) - Recurrent spacer dislocation (soft tissue incompetence, abductor failure) - Spacer fracture early (under 3 months) - infection, excessive loading - Medical deterioration (may preclude Stage 2, consider chronic suppression) ## Antibiotic Holiday Rationale **Purpose**: Unmask persistent infection that antibiotics suppress but don't eradicate **Protocol**: - Stop ALL antibiotics 2 weeks before Stage 2 - Clinical monitoring (fever, wound changes, pain) - Inflammatory markers (CRP, ESR) at 1 week and 2 weeks - Hip aspiration at 2 weeks **Interpretation**: - **CRP/ESR remain low, aspiration negative**: Proceed to Stage 2 - **CRP/ESR rise, aspiration positive**: Persistent infection - abort Stage 2 - **CRP/ESR rise, aspiration negative**: Investigate (imaging, repeat aspiration) **Risk**: - Systemic sepsis if highly virulent organism (rare) - Monitor patient clinically - Restart antibiotics if sepsis develops **Evidence**: Antibiotic holiday improves aspiration sensitivity from 40% to 75% for detecting persistent infection. Antibiotics suppress bacteria creating false reassurance. False negative aspiration occurs if on antibiotics - leads to reimplanting with active infection (50% failure rate vs 10% if infection controlled). Holiday is low risk (sepsis rare) with high benefit (accurate diagnosis). ## Exposure and Spacer Removal **Approach**: Same posterior approach through previous scar **Expect MORE DIFFICULT dissection than Stage 1**: - Extensive scar tissue from two previous surgeries - Distorted anatomy from spacer subsidence - Sciatic nerve encased in scar (highest risk) - Indurated capsule **Technique**: 1. Careful dissection through scar 2. Protect sciatic nerve (blunt dissection, early identification) 3. Deepen to joint, excise pseudocapsule 4. Dislocate hip posteriorly 5. Remove spacer **metal head** first 6. Remove **acetabular component** (osteotomes at interface) 7. Remove **femoral component** (may need high-speed burr if well-fixed) 8. Remove **ALL spacer cement fragments** (biofilm can form on retained cement) 9. Light debridement of any residual membrane/synovium 10. Ream acetabulum to bleeding bone (establish new bone bed) 11. Ream femoral canal to bleeding bone **Technical Challenge**: Stage 2 exposure often MORE challenging than Stage 1 - dense scar, distorted anatomy, nerve encased. Articulating spacer easier to remove than static (less cement, more modular). Remove ALL spacer cement - retained cement is biofilm substrate causing reinfection. Fresh debridement of bone surfaces essential - need bleeding bone bed for biological fixation. ## Tissue Sampling and Frozen Section **CRITICAL SAFETY CHECK**: Frozen section is final verification before reimplantation **Tissue Samples**: - Obtain **5-6 FRESH tissue samples** BEFORE reimplantation: 1. Capsule/pseudocapsule 2. Acetabular bone interface 3. Femoral bone interface 4. Soft tissue from different quadrants - Send for aerobic/anaerobic cultures (14-day hold) - Send for permanent histology **FROZEN SECTION** (mandatory): - Send capsule/interface tissue for immediate histology - **Over 5 PMN/HPF** = PERSISTENT INFECTION - Sensitivity ~80%, specificity ~95% **If Frozen Section POSITIVE (over 5 PMN/HPF) OR gross purulence**: - **ABORT reimplantation** - Place new antibiotic spacer with fresh high-dose antibiotics - Extended IV antibiotics (12 weeks) - Repeat CRP/ESR monitoring - Consider chronic suppression or salvage procedures **If Frozen Section NEGATIVE (under 5 PMN/HPF) and tissues appear clean**: - **Proceed with reimplantation** - Final cultures guide postoperative antibiotics (6 weeks if positive) **Critical Decision**: Frozen section at Stage 2 - over 5 PMN/HPF = ABORT reimplantation, place new spacer. Sensitivity ~80%, specificity ~95%. False negatives possible (antibiotics suppress but don't eradicate, dormant bacteria). If positive or gross infection: new spacer, extended antibiotics 12 weeks, consider chronic suppression or salvage. Cultures at Stage 2 detect persistent/new infection (10-20% positive despite normalized markers). ## Acetabular Reconstruction **Assess Bone Loss**: Paprosky classification **Reaming**: Sequential hemispherical reamers to bleeding bone, 1-2mm underream for press-fit **Reconstruction by Paprosky Type**: **Type I** (intact rim, minimal migration): - Standard uncemented hemispherical revision cup - Multiple screws (dome, posterior column) - Highly cross-linked polyethylene liner **Type IIA** (superior-medial wear, intact rim/columns): - Standard cup, may need small augment superomedial - Multiple screws into intact bone **Type IIB/IIC** (moderate deficiency, ischial lysis): - Jumbo cup (66-70mm) - excellent results - OR augments (porous tantalum or titanium) - Ensure 50% host bone contact **Type IIIA** (severe superior deficiency, under 50% contact): - Structural augment + cup - OR cup-cage construct (Ganz ring, Burch-Schneider cage) - Multiple screws into ilium, posterior column **Type IIIB** (severe medial wall loss or pelvic discontinuity): - Cup-cage construct (distraction cage) - OR custom triflange implant - OR cemented cup with cage support - May require plating of discontinuity first **General Principles**: - Aim for **50% host bone contact** for biological fixation - Multiple screws into intact bone (posterior column, ilium, dome) - **Avoid 3 o'clock and 9 o'clock positions** (external iliac vessels) - **HIGHLY CROSS-LINKED POLYETHYLENE** liner - Consider **DUAL MOBILITY** liner (see below) **Reconstruction Strategy**: Bone loss common after two-stage (debridement + spacer subsidence). Paprosky classification guides reconstruction. Need 50% host bone contact for biological fixation. Type I/IIA: standard revision cup. Type IIB/IIC/IIIA: jumbo cup (excellent results, simpler) or augments (porous tantalum). Type IIIB: cup-cage (antiprotrusio cage) or custom triflange (expensive, long wait). Screws in SAFE ZONES (avoid 3 o'clock, 9 o'clock - vessels). ## Femoral Reconstruction **Assess Bone Loss**: Paprosky femoral classification **Reconstruction by Paprosky Type**: **Type I** (metaphyseal bone intact): - Standard uncemented revision stem (tapered or proximally porous) - Press-fit in metaphysis **Type II** (metaphyseal compromise, intact diaphysis): - Extensively porous coated cylindrical stem (diaphyseal fixation) - 4-6 inches coating length - Scratch fit in diaphysis **Type IIIA** (metaphyseal damage, diaphyseal intact 4cm or more): - Extensively porous coated stem (need 4cm scratch fit for stability, 90% success) - OR modular tapered stem (Wagner-type, Reclaim) - Bypass ETO site by 2 cortical diameters (10cm) **Type IIIB** (extensive metaphyseal/diaphyseal damage, under 4cm fixation): - Modular tapered fluted stem (Wagner, Reclaim, MP) - long version - Megaprosthesis (elderly, tumor-like defects, unfit for complex reconstruction) - OR allograft-prosthetic composite (APC) - young patients, large defects **Cemented vs Cementless** (debated): - Most prefer **CEMENTLESS** (no biofilm substrate) - But some use **low-dose antibiotic cement** for older osteoporotic patients: - 1g vancomycin per 40g cement (NOT high-dose like spacer) - Provides some infection protection - Allows cement fixation in poor bone **If ETO**: Leave open until stem inserted, then reduce and cable (3+ cables) **Femoral Strategy**: Bone loss from debridement, ETO, spacer subsidence. Type III defects common - need diaphyseal fixation. Type IIIA: extensively porous coated (need 4cm scratch fit for 90% success) or modular taper. Type IIIB: long modular taper (Wagner, Reclaim - good results), megaprosthesis (elderly, tumor-like), or APC (young, large defects). Cemented vs cementless debated - most prefer cementless (no biofilm). If cement needed: use antibiotic-loaded (1g vancomycin per 40g, NOT high-dose). ## Instability Prevention - Dual Mobility **Dislocation Risk After Two-Stage**: 10-15% (vs 2-3% primary THA) **Reasons for High Risk**: - Soft tissue damage from infection - Abductor weakness (denervation, damage) - Multiple surgeries (scar, contracture) - Altered anatomy (bone loss, offset changes) **DUAL MOBILITY CUP - PREFERRED STRATEGY**: **Advantages**: - Reduces dislocation from 10-15% to 2-3% - Lower revision rate than constrained liner - Allows larger effective head size (total travel 54-60mm) - No risk of dissociation (unlike constrained) - Preserves ROM **Disadvantages**: - Intraprosthetic dislocation (rare, under 1%) - Polyethylene wear at dual articulations - More expensive **Alternative Strategies**: 1. **Constrained Liner** (for severe instability): - 10° lipped or fully constrained - Higher dissociation rate (5% at 5 years) - Use for salvage, severe abductor deficiency - Higher revision rate than dual mobility 2. **Larger Femoral Head** (if standard liner): - 36mm or 40mm - Increases jump distance - Limited by liner thickness (fracture risk) 3. **Optimize Offset**: - Lateralize acetabular component (eccentric reamer) - High offset or lateralized femoral stem - Tensions abductors 4. **Adjust Leg Length**: - Slight lengthening (1-2cm) tensions soft tissues - Avoid over 4cm (sciatic nerve palsy) 5. **Meticulous Soft Tissue Repair**: - Posterior capsule reconstruction - Short external rotators to trochanter - May need abductor advancement if deficient **Testing Stability**: - Trial components - Range of motion: flexion to 90°, internal rotation, adduction (Shuck test) - Should resist dislocation with moderate force - Ensure no impingement (neck-liner, bone-bone) **Instability Management**: Dislocation rate 10-15% after two-stage (vs 2-3% primary) - soft tissue damage, abductor weakness, multiple surgeries. Prevention: DUAL MOBILITY cup PREFERRED (reduces to 2-3%, lower revision rate than constrained). Constrained liner for severe instability (collateral damage, salvage) but higher failure rate (5% dissociation at 5y). Larger head (36-40mm) helps if standard. Meticulous soft tissue repair essential. Extended hip precautions 12 weeks. Dual mobility BEST balance - protection with lower complications. ## Final Implantation and Closure **If Trials Stable**: Proceed with final components **Acetabular**: - Insert final cup (press-fit, multiple screws in safe zones) - Insert final liner (dual mobility or constrained as planned) **Femoral**: - Insert final stem (press-fit or cemented) - Ensure distal fixation adequate (bypass ETO by 10cm) **Reduction**: - Reduce hip - should be stable with moderate force required - Recheck stability with Shuck test **If ETO Performed**: - Reduce trochanteric fragment anatomically - Fix with **3 or more cerclage cables** - May add vertical cable or specialized ETO plate if unstable - Ensure compression achieved **Soft Tissue Repair** (METICULOUS): - Repair posterior capsule (if tissue available) - Repair short external rotators to trochanter (piriformis, gemelli, obturators) - Ensure gluteus maximus closure - Adequate soft tissue tension for stability **Final Lavage**: Pulse lavage 3L saline **Closure**: - Close fascia lata with absorbable sutures - Subcutaneous with absorbable sutures - Skin (staples or subcuticular) - Drains optional (closed suction if used, remove 24-48h) **INTRAOPERATIVE IV ANTIBIOTICS**: - Vancomycin 1g IV - PLUS cefazolin 2g IV - OR organism-specific (meropenem if resistant) - ETO non-union (compromised bone from infection, need 3+ cables, protected WB) - Abductor failure (inadequate repair, avulsion, denervation) - Trendelenburg, instability - Dislocation early postop (inadequate soft tissue repair, patient non-compliance) - Fracture from component insertion (press-fit in weak bone - have cables/plates ready) - Screw penetration intrapelvic (vascular injury - know safe zones) ## Stage 2 Postoperative Antibiotics **CONTROVERSIAL - NO CONSENSUS** **Options**: 1. **No Additional Antibiotics**: - If Stage 2 cultures/frozen section negative - AND Stage 1 organism treated adequately (6-12 weeks) - Some evidence this is safe 2. **6 Weeks Organism-Specific IV Antibiotics**: - If Stage 1 cultures were positive - Even if Stage 2 negative - Most common practice - Same antibiotics as Stage 1 3. **CHRONIC ORAL SUPPRESSION** (indefinite): - Some institutions advocate for ALL two-stage patients - Options: Doxycycline 100mg PO BD, fluoroquinolone, or organism-specific - Reduces reinfection from 10-20% to 5-10% (observational data) - Balance benefit vs risk (C. diff, resistance, tendon rupture) **Most Evidence Supports**: - At least 6 weeks post-Stage 2 if original organism virulent (MRSA, Pseudomonas) - Chronic suppression for high-risk (immunosuppressed, previous failures) - Consult Infectious Disease **Monitoring**: - CRP/ESR every visit for **minimum 2 years** - Then annually lifelong - If CRP rises: investigate (X-ray, aspiration, consider PET/CT) **Postop Protocol**: Post-Stage 2 antibiotics debated - no RCT evidence. Most give at least 6 weeks organism-specific if Stage 1 cultures positive. Some centers advocate CHRONIC SUPPRESSION (doxycycline 100mg BD indefinitely) - reduces reinfection from 10-20% to 5-10% in observational studies. Rifampicin for Staph if biofilm concern. Monitor CRP/ESR for 2 years minimum (recurrence can be late). Counsel patient: surveillance lifelong, dental prophylaxis debated but many recommend. ## Postoperative Protocol **Hip Precautions**: **6-12 weeks** (strict, high dislocation risk) - Avoid flexion over 90 degrees - Avoid adduction across midline - Avoid internal rotation - Abduction brace for first 6 weeks if high risk **Weight-Bearing**: **If ETO performed**: - Toe-touch or 20kg partial weight-bearing until union confirmed - Serial X-rays at 2, 4, 6, 8 weeks - Progress to full weight-bearing when union seen (usually 6-8 weeks) **If no ETO and stable cementless fixation**: - Weight-bearing as tolerated (WBAT) immediately - Walker or crutches for comfort **If cemented**: - WBAT immediately **Physiotherapy**: - Gentle ROM initially (within precautions) - Progressive strengthening (especially abductors) - Gait training - Functional exercises - Aim for normalized gait by 3-6 months **Occupational Therapy**: - ADL education (dressing, toileting, bathing) - Hip precautions training - Adaptive equipment (raised toilet seat, sock aid, reacher) - Home safety assessment **Protocol**: Hip precautions 6-12 weeks (high dislocation risk from soft tissue damage). If ETO: protected WB until union (6-8 weeks), then progress. If no ETO: WBAT immediately. Aggressive physio for abductor strengthening. Extended precautions compared to primary THA due to soft tissue damage and multiple surgeries. ## Surveillance Protocol **Radiographs**: - 6 weeks post-Stage 2 - 3 months - 6 months - 12 months - Then annually lifelong **Look for**: - Component loosening (radiolucent lines, migration) - Osteolysis (bone loss around implants) - ETO union (if performed) - Fracture - Heterotopic ossification **Inflammatory Markers**: - **CRP and ESR** at each visit for **first 2 years** - Then annually lifelong - If CRP rises above 10 or ESR above 30: investigate **If Elevated Markers**: 1. X-ray (loosening, osteolysis) 2. Hip aspiration (cell count, culture) 3. Consider advanced imaging: - **PET/CT**: 95% sensitivity for infection - MRI with metal artifact reduction (MARS) - Bone scan + WBC scan **Clinical Assessment**: - Pain (location, character, functional limitation) - Function (walking distance, stairs, ADLs) - ROM - Gait (Trendelenburg, antalgic) - Leg length discrepancy - Patient satisfaction - Rising CRP/ESR (most sensitive) - Persistent pain (especially start-up pain) - Drainage from wound (late sinus tract) - Fever, systemic symptoms (rare unless acute) - Component loosening on X-ray (late sign) - High index of suspicion - aspirate if doubt ## Outcomes and Patient Counseling **Infection Eradication**: 85-90% at 2 years **BUT Higher Complications than Primary THA**: **Reinfection**: - 10-20% at 2 years - Can occur 5-10+ years later (late hematogenous seeding or dormant biofilm) - Same organism (residual biofilm) or new organism (hematogenous) **Dislocation**: - 10-15% (vs 2-3% primary THA) - Even with dual mobility: 2-3% - Soft tissue damage, abductor weakness **Aseptic Loosening**: - 10-15% at 10 years (vs 5% primary THA) - Bone quality compromised by debridement - Stress shielding from long stems **ETO Non-Union**: - 5-10% (higher with persistent infection) - Causes pain, Trendelenburg gait - May require ORIF if symptomatic **Chronic Pain**: - 15-20% report persistent pain - Multifactorial (muscle damage, nerve injury, bone loss, multiple surgeries) - Requires multimodal management **Leg Length Discrepancy**: - Common (bone loss, altered anatomy) - Accept under 2cm if stable - Shoe lift if symptomatic **Patient Satisfaction**: - **LOWER than primary THA** - Despite infection eradication, function compromised - Set realistic expectations pre-operatively **Dental Prophylaxis**: - Debated in literature - Many surgeons recommend lifelong antibiotics before dental procedures - Australian guidelines: consider for first 2 years or indefinitely if high risk **Counsel Patients**: - Not as good as primary THA (higher complications, lower satisfaction) - Lifelong surveillance required (CRP/ESR, X-rays) - Recurrence can occur years later - May need further surgery (revision for loosening, dislocation, reinfection) - Salvage options if fails (Girdlestone, arthrodesis, amputation) **Outcomes**: Two-stage revision achieves infection eradication 85-90%, BUT higher dislocation (10-15% vs 2-3% primary), higher loosening (10-15% at 10y vs 5% primary), reinfection 10-20% at 2y, patient satisfaction lower. Long-term surveillance ESSENTIAL - CRP/ESR every visit first 2 years. Recurrence can occur 5-10+ years later (late hematogenous or dormant biofilm). Counsel realistic expectations - NOT as good as primary THA. Salvage options if fails. ## Salvage Procedures if Two-Stage Fails **Repeat Two-Stage Revision**: - If young, good bone stock, first failure - Success rate 60-70% (lower than first two-stage) - Higher morbidity **Chronic Antibiotic Suppression**: - Indefinite oral antibiotics - Doxycycline 100mg BD or fluoroquinolone - Accept infected implant, suppress symptoms - For elderly, poor surgical candidates - Requires lifelong compliance **Girdlestone Procedure** (Excision Arthroplasty): - Remove ALL implants, cement, infected tissue - Leave as pseudarthrosis - Antibiotic spacer or antibiotic beads short-term, then remove - Pain relief 60-70% - Major limb shortening (3-5cm) - Requires walker or crutches lifelong - Poor function but infection controlled - For elderly, low demand, poor surgical candidates **Arthrodesis** (Hip Fusion): - Fuse hip in optimal position (25° flexion, 0° abduction, 0° rotation) - Requires good bone stock - Infection eradication excellent (over 95%) - Pain relief excellent - But loss of ROM, gait abnormalities, back pain (compensatory) - Difficult to convert to THA later - For young, active, failed multiple revisions **Amputation**: - Last resort - For life-threatening sepsis not controlled with debridement - For non-functional painful limb after multiple failures - Rare (under 1% of PJI cases) **Salvage Hierarchy**: If two-stage fails - (1) Repeat two-stage if young, good bone, first failure (60-70% success), (2) Chronic suppression if elderly, poor surgical candidate (doxycycline indefinitely), (3) Girdlestone if low demand, cannot tolerate surgery (pain relief 60-70%, poor function, walker lifelong), (4) Arthrodesis if young, active, failed multiple (excellent infection control and pain relief, but loss ROM and back pain), (5) Amputation for life-threatening sepsis or non-functional limb (rare, under 1%). ## References 1. **Osmon DR, Berbari EF, Berendt AR, et al.** Diagnosis and management of prosthetic joint infection: clinical practice guidelines by the Infectious Diseases Society of America. *Clin Infect Dis*. 2013;56(1):e1-e25. doi:10.1093/cid/cis803 2. **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.e2. doi:10.1016/j.arth.2018.02.078 3. **Haddad FS, Muirhead-Allwood SK, Manktelow ARJ, Bacarese-Hamilton I.** Two-stage uncemented revision hip arthroplasty for infection. *J Bone Joint Surg Br*. 2000;82-B(5):689-694. doi:10.1302/0301-620X.82B5.10668 4. **Hanssen AD, Spangehl MJ.** Practical applications of antibiotic-loaded bone cement for treatment of infected joint replacements. *Clin Orthop Relat Res*. 2004;(427):79-85. doi:10.1097/01.blo.0000143554.56897.26 5. **Younger ASE, Duncan CP, Masri BA, McGraw RW.** The outcome of two-stage arthroplasty using a custom-made interval spacer to treat the infected hip. *J Arthroplasty*. 1997;12(6):615-623. doi:10.1016/S0883-5403(97)90034-2 6. **Masri BA, Panagiotopoulos KP, Greidanus NV, Garbuz DS, Duncan CP.** Cementless two-stage exchange arthroplasty for infection after total hip arthroplasty. *J Arthroplasty*. 2007;22(1):72-78. doi:10.1016/j.arth.2006.02.156 7. **Gomez MM, Tan TL, Manrique J, Deirmengian GK, Parvizi J.** The fate of spacers in the treatment of periprosthetic joint infection. *J Bone Joint Surg Am*. 2015;97(18):1495-1502. doi:10.2106/JBJS.N.00958 8. **Choi HR, Kwon YM, Freiberg AA, Nelson SB, Malchau H.** Periprosthetic joint infection with negative culture results: clinical characteristics and treatment outcome. *J Arthroplasty*. 2013;28(6):899-903. doi:10.1016/j.arth.2012.10.022 9. **Trampuz A, Zimmerli W.** Diagnosis and treatment of infections associated with fracture-fixation devices. *Injury*. 2006;37(Suppl 2):S59-S66. doi:10.1016/j.injury.2006.04.010 10. **Beswick AD, Elvers KT, Smith AJ, Gooberman-Hill R, Lovering A, Blom AW.** What is the evidence base to guide surgical treatment of infected hip prostheses? Systematic review of longitudinal studies in unselected patients. *BMC Med*. 2012;10:18. doi:10.1186/1741-7015-10-18

Total Hip Arthroplasty - Two-Stage Revision for Chronic Periprosthetic Joint Infection

Total Hip Arthroplasty - Two-Stage Revision for Chronic Periprosthetic Joint Infection