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