import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: Exits pelvis through greater sciatic notch below piriformis, 2cm posterior to short external rotators, may be scarred or displaced in revision **Protection**: Early identification with vessel loop, gentle retraction, avoid excessive traction during exposure, palsy risk 2-5% in revision vs 0.5-1% primary **Location**: Exits pelvis above piriformis through greater sciatic notch, enters deep surface of gluteus medius and minimus muscles **Protection**: Limit proximal dissection to less than 5cm above greater trochanter tip, stay subperiosteal when separating abductors from ilium for rim exposure **Location**: Intrapelvic along pelvic brim anteriorly, 2-3cm anterior to acetabular rim at 2-4 o'clock position (right hip) **Protection**: Avoid anteroinferior acetabular screws (vascular danger zone), keep screws posterosuperior quadrant only, prevent medial wall perforation during reaming **Location**: Exits pelvis through obturator foramen medially and inferiorly, runs along medial wall of acetabulum **Protection**: Avoid medial wall perforation, careful reaming technique near floor, recognize anatomic landmarks (teardrop, transverse ligament) **Location**: Anterior to hip capsule in femoral triangle, femoral nerve lateral, artery central, vein medial **Protection**: Stay posterior with approach, avoid anterior dissection, recognize during anterior column fracture or intrapelvic cement extrusion ## Indications for Acetabular Revision ### Absolute Indications **Aseptic Loosening (Most Common 40-50%)** - Progressive pain with weight bearing - Radiographic lucencies greater than 2mm in all 3 DeLee-Charnley zones - Component migration greater than 3mm vertical or 5mm horizontal on serial radiographs - Acetabular cup tilt or change in position compared to post-operative baseline **Polyethylene Wear with Osteolysis** - Polyethylene wear rate exceeding 0.2mm per year (critical threshold) - Progressive osteolysis despite well-fixed shell (retained shell, liner exchange insufficient if osteolysis progressing) - Impending structural failure with large cavitary lesions **Recurrent Instability** - Multiple dislocations (typically 3 or more) despite closed reduction and conservative management - Requires acetabular revision to correct malposition (excessive anteversion or inclination) - Often combined with constrained or dual mobility liner **Infection** - Chronic periprosthetic joint infection requiring 2-stage revision (explantation, spacer, then reimplantation) - Acetabular component involvement demonstrated by positive cultures and imaging **Component Malposition** - Symptomatic malposition causing instability, impingement, or accelerated wear - Outside Lewinnek safe zone (inclination 30-50°, anteversion 5-25°) - High hip center with progressive superior migration and abductor insufficiency ### Relative Indications - Liner dissociation or locking mechanism failure (may be managed with liner exchange if shell stable) - Adverse reaction to metal debris (ARMD) from metal-on-metal bearings requiring revision to non-metal bearing - Pelvic discontinuity with acetabular instability - Severe metallosis requiring debridement and component revision ## Mandatory Pre-operative Infection Workup ### Serological Testing **ESR (Erythrocyte Sedimentation Rate)** - Threshold: Greater than 30 mm/hr suspicious for infection - Sensitivity 82%, specificity 85% - Can be elevated by inflammatory conditions, malignancy, renal disease **CRP (C-Reactive Protein)** - Threshold: Greater than 10 mg/L suspicious for infection - More specific than ESR, normalizes faster post-operatively - Sensitivity 96%, specificity 92% - Combined ESR and CRP improves diagnostic accuracy ### Joint Aspiration (Gold Standard) **Indications for Aspiration** - Any elevation in ESR or CRP - Clinical suspicion (pain, wound drainage, fever) - Should be performed OFF antibiotics for minimum 2 weeks (6 weeks preferred) **Aspiration Technique** - Fluoroscopic or ultrasound guidance preferred - Lateral approach (anterior to greater trochanter) avoiding neurovascular structures - Send for: cell count with differential, aerobic and anaerobic cultures (hold 14 days), Gram stain **Interpretation** - WBC greater than 3,000 cells/μL suspicious (sensitivity 84%, specificity 88%) - WBC greater than 10,000 cells/μL highly suspicious for infection - PMN percentage greater than 80% concerning for infection (sensitivity 84%, specificity 82%) - Culture positive = definite infection (but false negatives occur with biofilm, prior antibiotics) ### Adjunctive Tests for Equivocal Cases **Alpha-Defensin** - Synovial biomarker highly specific for infection - Sensitivity 97%, specificity 96% - Not affected by prior antibiotics - Expensive but excellent when ESR/CRP/cell count equivocal **Synovial CRP and IL-6** - Synovial fluid inflammatory markers - CRP greater than 6.9 mg/L = infection - IL-6 greater than 9,000 pg/mL = infection - High sensitivity and specificity **ESR/CRP Alone Misses 30% of Infections** - aspiration is mandatory in revision ## Imaging Assessment ### Standard Radiographs **AP Pelvis (Essential)** - Assess Kohler's line (ilioischial line) - violation indicates medial wall deficiency - Evaluate teardrop - obliteration suggests severe bone loss (Paprosky IIIB) - Measure superior migration from inter-teardrop line to cup center (Paprosky I less than 2cm, IIA 2-3cm, IIB/IIIA/IIIB greater than 3cm) - Assess ischial osteolysis - affects inferior support for reconstruction **Lateral Hip and Judet Oblique Views** - Judet obturator oblique (45° away from affected side) - visualizes anterior column and posterior wall - Judet iliac oblique (45° toward affected side) - visualizes posterior column and anterior wall - Essential for assessing column integrity and planning screw trajectories ### Advanced Imaging **CT Scan with 3D Reconstruction** - Indicated for Paprosky IIIA/IIIB severe bone loss - Accurate assessment of bone stock, defect morphology, and containment - Evaluate for pelvic discontinuity (fracture line through posterior column) - Plan screw trajectories and identify safe zones - Measure bone stock for custom triflange design if needed **MRI** - Limited role in acetabular revision planning - May identify soft tissue abnormalities, abductor tears, or collections - Metal artifact from prosthesis limits image quality ### Key Radiographic Landmarks - **Transverse Acetabular Ligament**: Marks true anatomic floor of acetabulum - **Teardrop**: Indicates medial wall integrity - obliteration = severe bone loss - **Kohler's Line**: Ilioischial line - medial violation indicates medial wall deficiency - **Ischium**: Inferior support - osteolysis compromises inferior fixation - **Ilioischial Line**: Assess for pelvic discontinuity ## Paprosky Acetabular Classification ### Type I - Minimal Bone Loss **Characteristics** - Intact acetabular rim (all quadrants) - Intact columns (anterior and posterior) - Superior migration less than 2cm from anatomic center - Minor osteolysis, minimal distortion **Reconstruction Strategy** - Standard hemispherical uncemented revision cup - Size 1-2mm larger than final reamer for press fit - Posterosuperior screws (2-3) for supplemental fixation - Highly porous coating (trabecular metal or titanium) **Expected Survival**: 90-95% at 10 years ### Type IIA - Superior Migration, Intact Rim **Characteristics** - Intact acetabular rim and columns - Superior migration 2-3cm from anatomic center - Distorted hemispheric shape but no segmental defects - Bone quality adequate for ingrowth **Reconstruction Strategy** - **Option 1**: Jumbo cup (66-74mm) to span distorted anatomy - preferred - **Option 2**: High hip center accepting 2-3cm superior migration (controversial) - Jumbo cup contacts more bone circumferentially achieving greater than 50% host contact - Multiple screws for fixation (3-5) **Expected Survival**: 85-90% at 10 years ### Type IIB - Segmental Defect, Superior-Posterior **Characteristics** - Greater than 25% segmental rim deficiency (typically superior and posterior) - Columns remain intact - Superior migration greater than 3cm - Remaining bone adequate for fixation **Reconstruction Strategy** - Highly porous metal augments (trabecular tantalum or titanium) to fill segmental defect - Augments convert uncontained (segmental) to contained defect - Augments fixed to host bone with screws - Revision cup spans native bone AND augment - Multiple cup screws into native bone and augment (4-6 screws) **Expected Survival**: 80-85% at 10 years ### Type IIC - Medial Wall Deficiency **Characteristics** - Medial wall osteolysis or deficiency - Rim preserved or minimally deficient - Columns intact - Cavitary defect medially **Reconstruction Strategy** - Medial bone grafting with morselized allograft or autograft (femoral head) - Reaming to healthy bleeding bone - Revision cup with screws - Alternative: trabecular metal augment if large medial defect **Expected Survival**: 80-85% at 10 years ### Type IIIA - Severe Rim Loss, Landmarks Present **Characteristics** - Greater than 50% rim loss (usually superior and posterior) - Columns intact - Ischium and teardrop still identifiable (not obliterated) - Superior migration greater than 3cm - Insufficient bone contact for standard cup **Reconstruction Strategy** - **Option 1**: Large jumbo cup (70-80mm) with extensive augments - **Option 2**: Cup-cage construct (Burch-Schneider or Ganz antiprotrusio cage) - Cage fixed to ilium superiorly and ischium inferiorly with screws/hooks - Cemented polyethylene cup within cage - Cage relies on screw fixation, not biological ingrowth **Expected Survival**: 75-80% at 10 years for cup-cage ### Type IIIB - Massive Bone Loss **Characteristics** - Massive bone loss with teardrop obliteration - Kohler's line violation (medial migration) - Ischial osteolysis compromising inferior support - Superior migration greater than 3cm - May have pelvic discontinuity **Reconstruction Strategy** - **Option 1**: Custom triflange implant (patient-specific 3D-printed flanges to ilium, ischium, pubis) - preferred for massive loss - **Option 2**: Cup-cage with massive augments or structural allograft - **Option 3**: Trabecular metal oblong cup - **Option 4**: Structural allograft (femoral head or distal femur) to restore bone stock, then cemented cup - If pelvic discontinuity present: MUST plate posterior column with reconstruction plate first **Expected Survival**: 60-75% at 10 years, custom triflange emerging data 85-90% at 5-10 years ## Patient Positioning and Preparation ### Positioning **Lateral Decubitus** (Standard for Posterior Approach) - Affected hip uppermost - Pelvis perpendicular to operating table (critical for accurate cup positioning) - Rigid pelvic positioners anteriorly and posteriorly - Beanbag or lateral positioners for stabilization - Verify positioning with fluoroscopy before draping **Table Selection** - Radiolucent table for intraoperative fluoroscopy - Consider fracture table for complex revisions if needed ### Surgical Approach **Posterior Approach (Moore/Southern) - Most Common** - Utilizes previous surgical scar when possible - Provides excellent acetabular exposure for revision - Allows proximal extension toward PSIS for rim visualization - Allows distal extension along femoral shaft **Incision** - Elliptical excision of previous scar (remove old scar tissue) - Total length 15-20cm (longer than primary) - Extend from PSIS toward greater trochanter, then along femoral shaft ## Exposure and Component Removal ### Soft Tissue Dissection 1. Incise fascia lata in line with skin incision 2. Split gluteus maximus in line with fibers (internervous plane) 3. **IDENTIFY SCIATIC NERVE EARLY** - place vessel loop around nerve for identification and protection 4. Extensive scar release - capsule thick, contracted, adherent to acetabulum 5. Tag short external rotators if identifiable (often atrophic in revision) 6. Proximal dissection if needed - separate gluteus medius from ilium staying less than 5cm above GT to avoid superior gluteal nerve ### Dislocation - Extensive capsulectomy required - remove thickened scarred capsule circumferentially - Flex 90°, adduct, internally rotate - May require bone hook on femoral neck or prosthetic head - If cannot dislocate: consider removing femoral head in situ with reciprocating saw ### Femoral Component Assessment **If Stable and Well-Positioned** - Perform isolated acetabular revision - Protect femoral Morse taper with metal cap during acetabular work **If Loose or Malpositioned** - Must revise both components (beyond scope of isolated acetabular revision) ### Liner Removal - Remove polyethylene or ceramic liner first using disimpaction tools or curved osteotomes - Assess liner wear pattern (anterosuperior wear indicates malposition) ### Acetabular Shell Removal **Loose Shell** - Often levers out with curved osteotomes - Minimal bone loss during removal **Well-Fixed Ingrown Shell** (Critical Technique) - Use curved osteotomes staying ON METAL SHELL (not on bone) to preserve bone stock - Work circumferentially 360° breaking ingrowth interface - Specialized Explant system with flexible cutting instruments - **Every millimeter of bone lost worsens reconstruction options** - Avoid excessive force **Cemented Cup** (Older Implants) - High-speed burr or hand instruments to remove cement meticulously - Avoid thermal necrosis from burr heat - Remove ALL cement to healthy bleeding bone ### Membrane Debridement - Remove ALL polyethylene wear debris - Excise particle disease membrane completely - Remove granulation tissue - Incomplete removal drives persistent osteolysis ## Bone Loss Assessment and Reconstruction ### Assess True Defect After component removal with acetabulum empty: - Classify by Paprosky system - Identify key landmarks (teardrop, transverse ligament, Kohler's line, ischium) - Assess containment: contained defects have bone walls, uncontained are segmental losses - **Check for pelvic discontinuity** - mobile hemipelvis with manipulation indicates posterior column fracture ### Acetabular Reaming **Goals** - Ream to healthy bleeding bone - Restore anatomic hip center (not high hip center) - Achieve maximum host bone contact (target 50%) **Technique** - Start with reamer 4-6mm smaller than estimated final size - Ream MEDIALLY toward transverse ligament and true floor (teardrop on fluoroscopy) - Remove sclerotic bone until bleeding bone encountered - Ream concentrically maintaining hemispheric shape - Target 40-45° inclination, 15-20° anteversion (Lewinnek safe zone) **Type-Specific Reaming** - Type I/IIA: Ream to uniform subchondral bone contact - Type IIB: Identify segmental defect, ream remaining intact bone, plan augment - Type IIC: Ream floor, prepare for medial grafting - Type IIIA/IIIB: Establish bleeding bed but don't over-ream - need remaining bone for fixation ### Type I/IIA Reconstruction **Standard Cup (Type I)** - Uncemented hemispherical revision cup - Size 1-2mm larger than final reamer for press fit - Porous titanium or trabecular metal surface - Position 40-45° inclination, 15-20° anteversion - Sequential impaction - listen for pitch change - Assess zero micromotion - Add 2-3 posterosuperior screws (supplemental fixation) **Jumbo Cup (Type IIA)** - 66-74mm diameter (2-4mm larger than standard) - Spans distorted anatomy achieving greater than 50% host contact - Same positioning and screw placement as standard - Preferred over high hip center ### Type IIB/IIC Reconstruction **Type IIB - Augments** - Highly porous metal augments (trabecular tantalum or titanium) fill segmental defect - Trial augment sizes to fill posterosuperior defect - Fix augment to host bone with 2-3 screws (6.5mm cancellous, engage 20-30mm) - Multiple augments if needed for large defects - Ream remaining native acetabulum - Insert revision cup spanning native bone AND augment - Cup screws through shell into native bone and augment (4-6 total screws) **Type IIC - Medial Grafting** - Morselized bone graft (allograft or autograft from femoral head) to restore medial wall - Ream carefully avoiding medial perforation - Insert cup with screws - Alternative: trabecular metal augment if large medial defect ### Type IIIA/IIIB Reconstruction **Type IIIA Options** *Option 1: Large Jumbo Cup with Augments* - 70-80mm cup contacting ischium inferiorly and ilium superiorly - Combined with large superior augment - Requires adequate bone stock *Option 2: Cup-Cage Construct* - Antiprotrusio cage (Burch-Schneider or Ganz) fixed to ilium (2 screws/hooks) and ischium (2 screws) - Cage provides structural support spanning defect - Relies on screw fixation, not ingrowth - Cemented polyethylene cup within cage - Position cage 40-45° inclination, 15-20° anteversion **Type IIIB Options** *Option 1: Custom Triflange (Preferred)* - Patient-specific 3D-printed implant with flanges to ilium, ischium, pubis - 3-6 month manufacturing time - Excellent fixation for massive bone loss - Cost 15,000-25,000 AUD - Emerging data suggests 85-90% survival at 5-10 years *Option 2: Cup-Cage with Massive Augments* - Multiple large augments to restore bone stock - Cage for structural support - Cemented cup within cage *Option 3: Structural Allograft* - Femoral head or distal femur allograft to restore bone stock - Cemented cup into allograft after incorporation - High failure rate, reserved for young patients **Pelvic Discontinuity Management** - MUST plate posterior column with long pelvic reconstruction plate FIRST - Then proceed with cup-cage or triflange reconstruction - Discontinuity will fail without plating ## Liner Selection for Stability ### Standard Liner **Indications** - Stable hip without instability history - Good soft tissue envelope - Intact abductor mechanism - Well-positioned components **Specifications** - Highly cross-linked polyethylene - Head size 28-36mm (larger reduces dislocation) - Minimum thickness 6-8mm for wear resistance ### Dual Mobility Liner (First-Line for Instability Prevention) **Indications** (Liberal Use in Revision) - Previous dislocation history - Abductor deficiency or trochanteric non-union - Poor soft tissue quality - Neuromuscular disease affecting hip stability - Revision surgery (higher baseline instability risk) **Advantages** - Large outer bearing (head-in-cup articulation) increases jump distance - Reduces dislocation from 10-20% (standard) to 2-3% - Superior outcomes compared to constrained liners - Allows greater ROM without impingement **Technique** - Clean shell thoroughly - Align orientation markers precisely - Press liner to full seating - Confirm locking mechanism engaged (manufacturer-specific) ### Constrained Liner **Indications** (Reserve for Specific Situations) - Cannot use dual mobility (size constraints) - Failed dual mobility (rare) - Extreme soft tissue deficiency **Disadvantages** - Higher torque transmitted to shell fixation (loosening risk) - Risk of liner dissociation if impingement occurs - Typically 10° capture angle **Avoid as First-Line** - dual mobility superior outcomes ### Cage Reconstruction Bearing **For Cup-Cage Constructs** - Cement polyethylene cup into cage with antibiotic-loaded bone cement - Position 40-45° inclination, 15-20° anteversion within cage - Can use standard or constrained polyethylene in cage ## Trial Reduction and Stability Testing ### Comprehensive Testing Protocol **Posterior Stability** (Most Critical for Posterior Approach) - 90° flexion + 40° internal rotation + adduction - "Shuck test" - should have zero subluxation or translation - Most common direction of instability **Anterior Stability** - Full extension + 40° external rotation - Should be stable without subluxation **Combined Loading** - Flex-adduct-internal rotation - Extend-adduct-external rotation - Abduction in all positions - Neutral rotation throughout ROM **ROM Assessment** - Test throughout full range looking for impingement - Identify positions of instability - Assess for component or bone impingement ### Troubleshooting Instability **If Unstable Despite Dual Mobility** (Something Wrong) - Check cup position (malposition most common cause) - Assess femoral version (retroversion causes posterior instability, anteversion causes anterior instability) - Evaluate soft tissue tension (over-lengthening reduces tension, under-tensioning inadequate) - Look for impingement (osteophytes, prominent component, heterotopic bone) **Stability Should Be Excellent** - accept nothing less ### Leg Length Assessment **Methods** - Overlapping patellae with heels together - Measure ASIS to medial malleolus bilaterally - Fluoroscopy comparing lesser trochanters **Goals** - Aim within 1cm of contralateral side - Some lengthening (1-2cm) acceptable for stability - Excessive lengthening (greater than 4cm) causes sciatic nerve palsy risk ### Fluoroscopic Confirmation - Cup inclination and anteversion within safe zone - Femoral head concentrically reduced in acetabulum - Leg length symmetry - No impingement throughout ROM ## Soft Tissue Repair ### Posterior Capsule Repair (Critical for Stability) **Evidence**: Capsular repair reduces dislocation 3-4x in primary THR, likely similar in revision **Technique** - Repair if tissue available (often attenuated in revision) - Heavy absorbable suture (0 or 1 Vicryl) - Capsule to capsule, or capsule to short external rotators, or capsule to greater trochanter via transosseous tunnels - Side-to-side repair preferred when possible ### Short External Rotator Repair **Structures** - Piriformis tendon - Conjoint tendon (obturator internus with gemelli) **Technique** - Reattach to posterior greater trochanter using: - Transosseous sutures (drill holes through GT) - Soft tissue repair if detached - Provides additional posterior stability ### Abductor Mechanism Assessment and Repair **Critical Assessment** - Gluteus medius integrity - Gluteus minimus integrity - Greater trochanter stability - Previous trochanteric osteotomy healed vs non-union **Repair Indications** - Any detachment or tear (abductor insufficiency major dislocation risk) - Trochanteric non-union or malunion **Technique** - Heavy non-absorbable suture (2 Ethibond or FiberWire) - Transosseous tunnels through greater trochanter - Side-to-side repair of muscle tears - Consider cerclage wires for trochanteric fractures **Abductor Insufficiency = High Instability Risk + Trendelenburg Gait** ### Irrigation and Closure **Irrigation** - Copious irrigation (6-9 liters normal saline) throughout case - Reduces infection risk - Final irrigation before closure **Drain Consideration** - Consider if large dead space, extensive dissection, or anticoagulation planned - Remove at 24-48 hours **Layered Closure** - Gluteus maximus fascia (1 Vicryl) - Fascia lata (1 Vicryl) - Subcutaneous layer (2-0 Vicryl) - Skin (staples or subcuticular monocryl) **Post-operative** - Abduction pillow - Sterile dressing - Hip precautions education ## Post-operative Management ### Weight Bearing Protocol **Excellent Fixation** (Press Fit or Well-Fixed Cage) - Weight bearing as tolerated immediately - Cemented or cementless ingrowth allows loading - Assistive device (frame or crutches) for first 6 weeks **Questionable Fixation** (Large Augments, Structural Graft, Marginal Stability) - Touch down weight bearing (toe-touch only) - Partial weight bearing 6-12 weeks - Progress based on radiographic evidence of ingrowth/integration - Serial X-rays to assess stability ### Hip Precautions (Posterior Approach) **Duration**: 12 weeks (longer than primary due to compromised soft tissues) **Restrictions** - No hip flexion greater than 90° (avoid low chairs, deep sofas, tying shoes) - No adduction across midline (avoid crossing legs) - No internal rotation (avoid pivoting on leg) **Equipment** - Abduction pillow at night (first 6 weeks) - Elevated toilet seat - Reacher and sock aid - Avoid low chairs ### Thromboprophylaxis **High Risk Patients** (Revision Surgery = High Risk) - LMWH (enoxaparin 40mg SC daily) OR - DOAC (rivaroxaban 10mg daily, apixaban 2.5mg BD) - Duration: 4-6 weeks minimum - Consider extended prophylaxis if very high risk **Mechanical Prophylaxis** - TED stockings - Intermittent pneumatic compression devices ### Antibiotic Prophylaxis **Standard Protocol** - Continue 24-48 hours post-operatively - Cephazolin 2g q8h (or vancomycin if MRSA risk) **If Infection Concern** - Extend based on intraoperative cultures - Infectious disease consultation - May require prolonged IV antibiotics ### Pain Management **Multimodal Analgesia** - Paracetamol 1g q6h regularly - NSAIDs if tolerated (ibuprofen 400mg q8h or celecoxib 200mg BD) - Opioids sparingly (oxycodone 5-10mg q4-6h PRN) - Neuropathic adjuncts if needed (gabapentin, pregabalin) ### Mobilization and Physiotherapy **Day 1-2** - Sit out of bed with physiotherapy supervision - Walking with frame or crutches - Hip precautions education **Week 1-6** - Progressive mobilization with assistive device - Abductor strengthening when allowed - ROM exercises within precautions **Week 6-12** - Wean from assistive devices - Progress strengthening - Functional activities training ### Radiographic Surveillance **Immediate Post-operative** - AP pelvis and lateral hip in recovery room - Assess component position, reduction, early complications **Follow-up Schedule** - 6 weeks (assess position, early loosening signs, advance weight bearing) - 3 months (assess stability, ingrowth progression) - 6 months (confirm fixation) - Annually for life (monitor for loosening, wear, osteolysis) ### Monitoring **Nerve Function** - Sciatic nerve assessment (foot dorsiflexion, sensation) - Palsy may present with delayed onset - EMG at 3 weeks if suspected palsy **Wound Healing** - Staple removal at 14-21 days (longer in revision) - Monitor for drainage, erythema, dehiscence **Mobilization Progress** - Gait pattern - Assistive device independence - Stairs capability ## Long-term Outcomes ### Survival Data **AOANJRR 2023 Report** - Acetabular revision 10-year survival: 87% overall - Cementless revision cups: 88.6% survival - Cemented revision cups: 82.9% survival - Re-revision rate: 10-15% at 10 years **Paprosky Type-Specific Survival** - Type I/IIA (minor defects): 90-95% at 10 years - Type IIB/IIC (moderate defects): 80-85% at 10 years - Type IIIA (severe, landmarks present): 75-85% at 10 years - Type IIIB (massive loss): 60-75% at 10 years (cup-cage) - Custom triflange (Type IIIB): 85-90% at 5-10 years (emerging data) **Isolated Acetabular vs Both-Component Revision** - Isolated acetabular: Better outcomes, less bone loss, faster recovery - Both-component: Lower survival, more complications, longer operative time ### Reasons for Re-revision - Aseptic loosening: 35% (most common late failure) - Dislocation: 30% (preventable with dual mobility) - Infection: 20% (chronic periprosthetic infection) - Fracture: 10% (periprosthetic acetabular fracture) - Other: 5% (liner wear, component failure) ### Functional Outcomes **Pain Relief** - Excellent in 80-90% of patients - Most improve from pre-revision state - Some chronic pain persists in 10-20% **Function** - Oxford Hip Score: 35-40 (vs 42-45 for primary THR) - Most patients NOT restored to primary THR function level - Significant improvement from pre-revision disability **Patient Satisfaction** - 75-85% satisfied with outcome - Lower than primary THR (90-95% satisfaction) - Expectation management crucial ### Dual Mobility Outcomes **Dislocation Reduction** - Standard liner revision: 10-20% dislocation rate - Dual mobility revision: 2-3% dislocation rate - Dramatic improvement in stability outcomes **Longevity** - Excellent survivorship at 10-15 years - Concerns about intraprosthetic dislocation rare (less than 1%) - No significant increase in aseptic loosening vs standard ### Cup-Cage Construct Outcomes **Survival** - 70-80% at 10 years - Eventual loosening as screws fail (relies on screws, not ingrowth) - Salvage procedure for severe bone loss **Complications** - Screw loosening over time - Cage migration - Increased dislocation if malpositioned ### Custom Triflange Outcomes **Emerging Data** (5-10 Year Follow-up) - 85-90% survival at 5-10 years - Excellent fixation for massive bone loss (Paprosky IIIB) - Low dislocation rates with proper positioning - Becoming gold standard for Type IIIB reconstruction **Advantages** - Patient-specific anatomy - Fixation to all three columns (ilium, ischium, pubis) - Immediate stability (screw fixation) - Potential for ingrowth (porous coating) **Disadvantages** - High cost (15,000-25,000 AUD) - Long manufacturing time (3-6 months) - Requires advanced imaging and planning ### Follow-up Schedule **Lifelong Surveillance Required** - Year 1: Every 3 months - Year 2: Every 6 months - Year 3+: Annually for life **Assessment at Each Visit** - Symptoms (pain, instability, function) - Examination (ROM, stability, Trendelenburg) - Imaging (component position, lucencies, migration, osteolysis) **Red Flags Requiring Investigation** - New or progressive pain - Instability or feeling of subluxation - Loss of function - Radiographic lucencies greater than 2mm - Component migration - Expanding osteolysis ## References 1. **Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR).** Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report. Adelaide: AOA, 2023. Available at: https://aoanjrr.sahmri.com/annual-reports-2023 2. **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 3. **Garbuz DS, Morsi E, Mohamed NN, Gross AE.** Classification and reconstruction in revision acetabular arthroplasty with bone stock deficiency. *Clin Orthop Relat Res* 1996;(324):98-107. doi:10.1097/00003086-199603000-00013 4. **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 5. **Abdel MP, Lewallen DG, Berry DJ.** Periprosthetic joint infection: the role of dual mobility implants in total hip arthroplasty. *Bone Joint J* 2014;96-B(11 Suppl A):60-63. doi:10.1302/0301-620X.96B11.34333 6. **Berend KR, Lombardi AV, Mallory TH, et al.** The long-term outcome of 755 consecutive constrained acetabular components in total hip arthroplasty: examining the successes and failures. *J Arthroplasty* 2005;20(7 Suppl 3):93-102. doi:10.1016/j.arth.2005.06.001 7. **DeBoer DK, Christie MJ, Brinson MF, Morrison JC.** Revision total hip arthroplasty for pelvic discontinuity. *J Bone Joint Surg Am* 2007;89(4):835-840. doi:10.2106/JBJS.F.00313 8. **Villatte G, Erivan R, Barbet R, et al.** Efficacy and safety of antibiotic-loaded bone cement in the prevention of periprosthetic joint infection after total hip arthroplasty: a systematic review and meta-analysis of randomized controlled trials. *J Bone Joint Surg Am* 2020;102(7):634-640. doi:10.2106/JBJS.19.00759 9. **Tarity TD, Koch CN, Burket JC, Wright TM, Westrich GH.** Fretting and corrosion at the backside of modular cobalt chromium acetabular inserts: a retrieval analysis. *J Arthroplasty* 2017;32(3):1033-1039. doi:10.1016/j.arth.2016.09.038 10. **Kosashvili Y, Backstein D, Safir O, Lakstein D, Gross AE.** Acetabular revision using an anti-protrusion (ilio-ischial) cage and trabecular metal acetabular component for severe acetabular bone loss associated with pelvic discontinuity. *J Bone Joint Surg Br* 2009;91(7):870-876. doi:10.1302/0301-620X.91B7.22181

Revision Total Hip Replacement - Acetabular Component

Revision Total Hip Replacement - Acetabular Component