INFECTED TOTAL HIP REPLACEMENT(Prosthetic joint infection {PJI} )

11 Jan INFECTED TOTAL HIP REPLACEMENT(Prosthetic joint infection {PJI} )

Epidemiology

• common cause of revision arthroplasty
• primary joint replacement
  • 0.5 – 2 % total knee replacement
  • 0.3 – 1.3 % in total hip replacement
• Revision joint replacement
  • 5 – 6 % I total knee arthroplasty
  • 3 – 4 % in total hip arthroplasty
    • BJJ prospective study
      • 0.57% in hip replacement
      • 0.86% in knee replacement
• Most common organism
  • Coagulase negative staphylococcus(MC)
  • STAPH. Aureus
  • Enterococci
  • Streptococci

Prevention

• Pre operative
  • Separate trauma patient and infected patients with joint replacement patients
  • Any septic foci to the treated first ( feet, urinary, respiratory and dental)
  • Shave in anaesthesia room
  • nasal decolonisation
  • avoid intra-articular steroid injection
  • sugar control
• Intra-operative
  • antibiotic impregnated cement
  • broad spectrum antibiotic on induction
  • clean theatre with laminar flow
  • body exhaust suit
  • Control theatre traffic
  • Gentle handling of soft tissue during surgery
  • Antibiotic covered foleys catheterisation as bacteria increases from 1% to 30 % if catheter left for 4 days.

Classification

• Musculoskeletal infection society criteria
  • major criteria
    • presence of sinus tract
    • culture positive at two separate occasion
  • Minor criteria
    • increased WBC > 3000cells / micro lt 3 points
    • synovial polymorphs > 80% 2 points
    • positive alpha defensin 3 points
    • synovial CRP > 6.9 1 point
    • CRP> 10mg/l or d-dimer > 860 ng/ml 2 points
    • ESR > 30/hr 1 point
    • intra operative
      • positive histology 3 points
      • positive purulence 2 points
      • one positive culture 2 points
  • > 6 infected, 5 inconclusive, < not infected

Investigation

• Blood tests
  • ESR AND CRP
  • IL-6 sensitive and specific(97% and 91%)
  • Procalcitonin
  • ALpha defensin test- 97% sensitive and 96% specific, false positive with metallosis
  • PCR of the aspirate
  • Synovial fluid aspiration , if dry tap saline injection and reaspiration provides accurate diagnostic information.
• Histology
  • Intraoperative tissue culture
    • 7 samples
  • intraoperative frozen section
    • 10 WBC/ high-power field
• Radiology
  • xrays
  • bone scan
    • sensitive if negative
    • can remain positive for 2 years
  • PET scan
    • sensitive and specific 98%

Treatment

• Non operative
  • chronic antibiotic therapy
    • for patients unfit for surgery
    • patient refusing surgery
• operative
  • polyethylene exchange with implant retention
    • for acute infection <3 weeks duration
    • consists of thorough debridement, antibiotics as per sensitivity and retaining prosthesis
  • one stage revision
    • for healthy patients with known and splatted organism and with good antibiotic sensitivity, no sinus tract, health soft tissue, no graft required, no prolonged antibiotic use. in such patient one stage revision can be done
    • variable success with tis technique 75 to 100%
  • two stage revision
    • gold stantard
    • for chronic > 4 weeks
    • medically fit papatient with good bone stock, normal lab and clinical parameters and a negative culture obtained after two weeks of stopping antibiotics
    • intros technique implant is removed antibiotic spacer is inserted, intravenous antibiotics for 4 to 6 weeks followed by prosthesis implantation.
    • outcome6 weeks antibiotics and spacer followed by preimplantation has excellent results 70 to 90%
  • resection arthroplasty
    • poor bone stock
    • recurrent infection
    • medically unfit for surgery
    • failure of multiple previous surgeries
    • elderly non ambulatory patient
  • arthrodesis
    • recurrent infection
    • poor bone stock
  • amputation
    • severe pain with bone and soft tissue severely damaged and vascular compromise