12. 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)
13. 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
14. 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
16. Aseptic/Mechanical Loosening
• Most common indication
for revision
• Regular radiological follow-
up
• Observe zones
• Observe progression
• Note symptoms
• Early to avoid depleted
bone stock
18. Wear of Articular Bearing Surface
• Bearing
– Traditional Poly
– UHMWPE
– Ceramic
– Metal
• Ceramic
– Fractures?
– SQUEAKS
19. Osteolysis
• Tissue response to wear debris
• Debris Phagocytosis Macrophage
activation OSTEOLYSIS
• Most common with TRADITIONAL
polyethylene bearings
26. Infection
• Clean air theatre
• Elective wards
• Skin prep
• Surgical technique
– Time
– Tissue handling
• Patient factors
• Abx v Surgery?
27. Infection
• 90% Gram Positives
– Staph Aureus
– CNS
• But Gram Negatives increasing!
• Only 12% have systemic symptoms
28. Serological investigation - PJI
• White blood cell count
Usually normal in pt with implant infection
When elevated – infection is usually obvious
29. Serological investigation - PJI
• ESR
>30 – 82% sensitivity
85% specificity
• CRP
>10 – 96% sensitivity
92% specificity
Both elevated – 83 % probability
Both normal – Eliminate infection
30. Serological investigation – PJI
Investigational
• Interleukin -6
Produced by monocyte and macrophages
Returns to normal 48 hrs post op
• Procalcitonin
31. Radionuclide imaging - PJI
Bone 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
41. 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
42. Molecular Techniques - PJI
• Polymerase chain reaction ( PCR ) – aspirate
Target gene – 16S RNA
High False positive
• Microarray and proteomic technology
Target Specific bacterial genes
Profile of genes ( microarray ) and proteins ( Proteomic )
43. Musculoskeletal infection society
(MSIS) - PJI Criteria
• Sinus Tract
• Isolated pathogen – 2 separate tissue culture /Specimen
• Four of following criteria
1.ESR
2.CRP
3.Synovial white cell count
4.Synovial PMN %
5.> 5 neutrophil/ High power field- 5 field
44. 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
45. 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%
48. Cost of Revision
Activity Cost per case
Total Income £10,097
Total 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
49. Cost of Revision
Procedure LOS (days) Total Cost
Periprosthetic Fracture 16 £18,400
1st
Stage/Pseudarthrosis 17 £14,240
Exchange Resurfacing 6 £8,980
Direct Exchange 7 £9,230
50. 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
51. 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
52. Special instruments for revision THR
• High speed drills
• High speed burrs
• Long . Narrow handle
osteotomes
• Flexible osteotomes
• Explant acetabular
extractor
54. 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
55. 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??
56. Summary
• Monitor new pains
– Startup pain
– Groin pain
• Suspect wear and loosening
• Suspect infection
• Check XR
• Early referral
