Revision thr indication, investigation & preparation
- 2. Background • 86,488 hips in 2012 –7.5% increase • Revision hips 12% –11% 2011
- 4. Age at THR
- 5. Age at THR Av Age 68.7 yrs
- 6. BMI
- 7. BMI
- 9. Failure Method Method 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%
- 10. Failure Method Method 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%
- 11. Failure Method Method 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%
- 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
- 15. Timing of THR Failure • 1.8% failure 9 years
- 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
- 20. Dislocation/Instability • Dislocation 1-2% • Component position – Acetabulum – Femoral • Soft tissue – Tension (offset) – Function • Components used – Head size – Constrained
- 21. Metal on Metal Hips
- 22. Metal on Metal Hips
- 23. Metal on Metal Hips
- 24. Metal on Metal Hips
- 25. 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
- 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
- 32. Radionuclide imaging – PJI Sequential Gallium scanning • Gallium 65 citrate • Bound to Transferrin • Complementary to scintigraphy • Uptake – inflammation • Accuracy – 70%- 80%
- 33. Radionuclide imaging – PJI Labelled leucocyte scintigraphy • Indium 111 • Labelling inflammatory cells – neutrophils • Increased periprosthetic activity – infection • Accumulates in infection • Complimentary bone marrow scan – Tc99m • Accuracy 90%
- 34. Radionuclide imaging – PJI Investigational agents • Technitium labelled Ciprofloxacin • Technitium labelled murine monoclonal antibody
- 35. Radionuclide imaging – PJI PET scan • Fluoro deoxy glucose • Increased metabolic activity – increased uptake • 91% Sensitivity , 72 % Specificity • False positive – particle induced inflammation – aseptic loosening
- 36. Joint aspiration – PJI Gram Stain & Culture • Strong suspicion infection Sensitivity – 57% - 93 % Specificity – 88% - 100 % • 2 weeks after antibiotics • Enriched culture – 14 days • False positive - Contamination
- 37. Joint aspiration – PJI Leucocyte count • Total count • Differential count • > 500 /micro Liter • Neutrophil – 64%
- 38. Joint aspiration – PJI Inflammatory markers • Synovial fluid – CRP • Synovial leukocyte esterase
- 39. Intraoperative Gram stain – PJI • Sensitivity – 27 % - No Role
- 40. Intraoperative Tissue culture– PJI • Sensitivity – 94% • Specificity 97% • Not always positive • 5-6 samples • Ultrasonification of prosthesis – disrupt glycocalyx
- 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%
- 46. Infection Single Stage Stage 1 Stage 2 Hip Excision 24% 37% 36% 3% Up to 90% cure
- 47. Radical Debridement • Essential to the procedure • Treat like a tumour
- 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
- 53. EXPLANT
- 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
- 57. Thank You