ASEPTIC LOOSENING OF THR - DNB Orthopaedics MS Orthopedics MRCS Exam GUIDE -

DNB Orthopaedics  MS Orthopedics  MRCS Exam GUIDE -

Orthopaedic Guidance for DNB Orthopaedics,MS Orthopaedics and Mrcs exams.Cme courses for orthopaedic surgeons.Davangere notes,solved question papers.DNB Ortho,MS Ortho MRCS,Exam Guide videos and notes 9087747888


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Sunday 9 July 2017



  • loosening most serious complication of THR – most common cause of revision
    • septic – d/t infection
    • aseptic – d/t osteolysis
  • generation of wear particles – access of wear particles to periprosthetic bone – cellular response to particulate debris
  • main source of particulate debris is polyethylene liner
  • all periprosthetic area accessible to joint fluid (effective joint space) are vulnerable
  • effective joint reduced by
    • porous coating of proximal stem
    • fewer screw holes in acetabular component
Clinical features
  • may be asymptomatic
  • groin pain more during initial weight bearing (start up pain)
  • pain alleviated by rest – aggravated by rotation of hip

Radiographic features
  • Cemented components
    • Femoral stem
      • definitive loosening
        • migration of the component
        • # or fragmentation of cement
        • # or deformation of the component
        • radiolucency at cement bone interference
      • probable loosening
        • radiolucency at cement bone interference at periphery of component >50% of circumference – at least in one radiograph
      • possible loosening
        • <50% stem circumference and less than 100% periphery of the component
    • acetabular components
      • radiolucency >2mm wide surrounding the entire component
      • migration of cup : change in version and horizontal inclination
  • Uncemented components
    • radiographic signs of bone ingrowth and stable fixation
      • spot welding at distal porous coated surface
      • stress shielding of medial cortex
      • absence of radiolucent or reactive lines on lateral cortex
    • stable fibrous fixation
      • absent spot welds
      • lack of stress shielding of medial cortex
      • radiolucent line around the circumference of the component - <1mm wide
      • reactive bone formation parallel to stem
      • slight calcar hypertrophy
    • unstable fibrous fixation
      • calcar hypertrophy
      • solid distal
      • subsidence or migration of component
      • reactive zone around the stem that is divergent
Technical problems contributing to stem loosening
  • failure to remove soft cancellous bone while preparing prosthesis bed
  • failure to remove all trabecular bone from the canal
  • inadequate quantity of cement
  • inadequate pressurization of cement
  • failure to centralize the stem
  • presence of voids in the cement
  • failure to keep the bolus of cement intact to avoid lamination
  • failure to prevent stem motion while cement is hardening
  • aseptic loosening is a radiographic diagnosis
  • does not constitute an indication of surgery
  • loose symptomatic components can be revised if patient can tolerate another surgery
  • asymptomatic cases : surgery in progressive osteolysis
    • so close follow up in such cases
    • early stages of osteolysis : lesion bone grafted along with exchange of acetabular liner and femoral head - Orthopaedic Guide. Hit subscribe to get updates and watsapp 9087747888
Orthopaedics made simple for DNB MS MRCS Support and Guidance for DNB Orthopaedics, MS Orthopaedics and Orthopaedic Surgeons. DNB Ortho MS Ortho MRCS Exam Guide Diplomate of National Board

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