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

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

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

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

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

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

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

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

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

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

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

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

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)

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)

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

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

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

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)

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)

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)

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)

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)

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)

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

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

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)

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)