Date post: | 15-Apr-2017 |
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Revision Hip Replacement
Background
• 86,488 hips in 2012–7.5% increase
• Revision hips 12%–11% 2011
TJA Volume Estimates
Age at THR
Age at THR
Av Age 68.7 yrs
BMI
BMI
Failure Method
Failure MethodMethod Percentage
1 Aseptic Loosening 40%
2 Pain 23%
3 Dislocation/Subluxation 13%
Lysis
Soft Tissue Reaction
6 Infection 12%
Acetabular Component Wear
8 Periprosthetic Fracture 8%
9 Malalignment 5%
10 Implant Failure 3%
Failure MethodMethod Percentage
1 Aseptic Loosening 40%
2 Pain 23%
3 Dislocation/Subluxation 13%
Lysis
Soft Tissue Reaction
6 Infection 12%
Acetabular Component Wear
8 Periprosthetic Fracture 8%
9 Malalignment 5%
10 Implant Failure 3%
Failure MethodMethod Percentage
1 Aseptic Loosening 40%
2 Pain 23%
3 Dislocation/Subluxation 13%
Lysis 13%
Soft Tissue Reaction 13%
6 Infection 12%
Acetabular Component Wear 12%
8 Periprosthetic Fracture 8%
9 Malalignment 5%
83%
Aims of Revision Hip
• Removal loose components• Limit destruction of host bone/soft tissue• Reconstruction bone defects– Metal– Bone Graft
• Stable revision implants• Restore normal hip COR (biomechanics)
Timing of THR Failure• Early– Recurrent dislocation– Infection– Implant failure– Intra-operative fracture
• Later– Wear of bearing surface– Osteolysis– Mechanical loosening– Infection– Peri-prosthetic fracture
Timing of THR Failure• Early– Recurrent dislocation– Infection– Implant failure– Intra-operative fracture
• Late– Wear of bearing surface– Osteolysis– Mechanical loosening– Infection– Peri-prosthetic fracture • Metal on Metal
Timing of THR Failure
• 1.8% failure 9 years
Aseptic/Mechanical Loosening
• Most common indication for revision
• Regular radiological follow-up
• Observe zones• Observe progression• Note symptoms• Early to avoid depleted
bone stock
Aseptic/Mechanical Loosening
Gruen DeLee-Charnley
Wear of Articular Bearing Surface
• Bearing– Traditional Poly– UHMWPE– Ceramic– Metal
• Ceramic– Fractures?– SQUEAKS
Osteolysis• Tissue response to wear debris
• Debris Phagocytosis Macrophage activation OSTEOLYSIS
• Most common with TRADITIONAL polyethylene bearings
Dislocation/Instability• Dislocation 1-2%• Component position– Acetabulum– Femoral
• Soft tissue– Tension (offset)– Function
• Components used– Head size– Constrained
Metal on Metal Hips
Metal on Metal Hips
Metal on Metal Hips
Metal on Metal Hips
Peri-Prosthetic Fracture
• Stress risers• Osteoporotic bone• Implant fixation• Vancouver:– A- trochanteric– B- prosthesis
• 1- Implant stable• 2- Implant loose• 3- plus poor bone
– C- distal
Infection• Clean air theatre• Elective wards• Skin prep• Surgical technique– Time– Tissue handling
• Patient factors• Abx v Surgery?
Infection
• 90% Gram Positives– Staph Aureus– CNS
• But Gram Negatives increasing!
• Only 12% have systemic symptoms
Serological investigation - PJI
• White blood cell count
Usually normal in pt with implant infection
When elevated – infection is usually obvious
Serological investigation - PJI
• ESR >30 – 82% sensitivity 85% specificity
• CRP >10 – 96% sensitivity 92% specificity
Both elevated – 83 % probabilityBoth normal – Eliminate infection
Serological investigation – PJIInvestigational
• Interleukin -6 Produced by monocyte and macrophagesReturns to normal 48 hrs post op
• Procalcitonin
Radionuclide imaging - PJIBone scintigraphy
• Technitium 99
Uptake - Rate of blood flow and Bone Formation
Diffuse uptake -Infection – osteolysis
Aeptic loosening – inflammation
Accuracy 50 – 70 %High negative predictive value
Radionuclide imaging – PJISequential Gallium scanning
• Gallium 65 citrate
• Bound to Transferrin
• Complementary to scintigraphy
• Uptake – inflammation
• Accuracy – 70%- 80%
Radionuclide imaging – PJILabelled leucocyte scintigraphy
• Indium 111• Labelling inflammatory
cells – neutrophils• Increased periprosthetic
activity – infection• Accumulates in infection• Complimentary bone
marrow scan – Tc99m• Accuracy 90%
Radionuclide imaging – PJIInvestigational agents
• Technitium labelled Ciprofloxacin
• Technitium labelled murine monoclonal antibody
Radionuclide imaging – PJIPET scan
• Fluoro deoxy glucose
• Increased metabolic activity – increased uptake
• 91% Sensitivity , 72 % Specificity
• False positive – particle induced inflammation – aseptic loosening
Joint aspiration – PJIGram Stain & Culture
• Strong suspicion infectionSensitivity – 57% - 93 %Specificity – 88% - 100 %
• 2 weeks after antibiotics• Enriched culture – 14 days• False positive - Contamination
Joint aspiration – PJILeucocyte count
• Total count• Differential count
• > 500 /micro Liter• Neutrophil – 64%
Joint aspiration – PJIInflammatory markers
• Synovial fluid – CRP
• Synovial leukocyte esterase
Intraoperative Gram stain – PJI
• Sensitivity – 27 % - No Role
Intraoperative Tissue culture– PJI
• Sensitivity – 94%• Specificity 97%• Not always positive• 5-6 samples
• Ultrasonification of prosthesis – disrupt glycocalyx
Intraoperative Frozen section– PJI• Preop – false elevation
of ESR and CRP• Intra- op – joint looks
non healthy
• Sensitivity – 85%• Specificity – 90%
• > 5 PMN / high power field - Infection
Molecular Techniques - PJI
• Polymerase chain reaction ( PCR ) – aspirateTarget gene – 16S RNAHigh False positive
• Microarray and proteomic technologyTarget Specific bacterial genesProfile of genes ( microarray ) and proteins ( Proteomic )
Musculoskeletal infection society (MSIS) - PJI Criteria
• Sinus Tract• Isolated pathogen – 2 separate tissue culture /Specimen
• Four of following criteria 1. ESR2. CRP3. Synovial white cell count4. Synovial PMN %5. > 5 neutrophil/ High power field- 5 field
Synovasure – Alfa Defensin
Synovasure Performance
95% confidence interval
Sensitivity 97.4% 86.1 – 99.6%
Specificity 95.8% 90.5% 98.6%
Alfa Defensin – antimicrobial peptide – released by neutrophils in response to pathogens
Infection
• Early < 3 weeks• Late > 3 weeks
• Cure with DAIR ( Debridement , Antibiotic , Implant Retention )– < 1 week up to 90%– 1 – 2 weeks 50/50– 3 weeks plus <10%
Infection
Single Stage Stage 1 Stage 2 Hip Excision24% 37% 36% 3%
Up to 90% cure
Radical Debridement
• Essential to the procedure
• Treat like a tumour
Cost of RevisionActivity Cost per caseTotal Income £10,097Total Costs £11,998 (-£1,901) Theatre £3,181
Nursing £1,610
Corporate Costs £1,217
Prosthetics £1,132
Consultant £746
Site costs £688 Drugs £438
Radiology £96
Pathology £94
Pharmacy £88
Cost of Revision
Procedure LOS (days) Total CostPeriprosthetic Fracture 16 £18,4001st Stage/Pseudarthrosis 17 £14,240Exchange Resurfacing 6 £8,980Direct Exchange 7 £9,230
Revision
• Much more difficult than primary• Poor results (comparatively)– Up to 20% infection rate– 29% failure at 8 years– 5% dislocation risk
• Require excellent pre-op planning with good choice of implant
Pre-op
• Good films, long leg AP and Lat.• CT for acetabulum?• Get original op note for component size and
make• Get equipment to remove• Order bone struts etc.• Have a good choice of prosthesis
Special instruments for revision THR
• High speed drills
• High speed burrs
• Long . Narrow handle osteotomes
• Flexible osteotomes
• Explant acetabular extractor
EXPLANT
Surgery - Femur
• Use previous skin incision if possible• In-cement revision• Cement out from top?• Extended trochanteric osteotomy• Radical debridement in infection• Bypass stress-riser with long stem
Surgery - Acetabulum
• Consider uncemented with screws if rim is intact (or at least 2/3)
• Bone graft defects (controversial in infection)• Structural allograft in large defect– High failure rate (40%) if resorbed
• Mesh? Cage? Trabecular metal?• Dual Mobility Cups• Constrained liner??
Summary
• Monitor new pains– Startup pain– Groin pain
• Suspect wear and loosening• Suspect infection• Check XR• Early referral
Thank You