Acetabular Component Revision

THR menu / Revision THR

• acetabular component

Discussion

• note that some of the problems seen in dysplasia are frequently encountered in revision THR;
• indications for acetabular revision:
  • sepsis, component malposition, impingement, polyethylene wear, pelvic osteolysis, recurrent dislocation, progressive protrusio, and component loosening;
• evaluation of the painful THR

examination:

• examination for loosening
• previoius incisions;
• contracture of the flexors and adductors (adds to complexity of the case);
• leg-length inequality is noted;
  • ref: Surgical Treatment of Limb-Length Discrepancy Following Total Hip Arthroplasty.
• neurovascular status of the limbs is recorded (EMG can be ordered if necessary);
  • power of the abductor muscles is noted;
  • marked Trendelenburg gait may indicate that abductors are non functional;

preop planning » (radiographs, equipment, implant selection);

• radiographic evaluation of acetabular components: (Paprosky Classification)
• classification of defects
• extraction instruments
• cell saver;
• rule out infection:
  • in addition to preoperative hip aspiration, consider culture of nares since preoperative staph aureus nasal carriage is associated with postoperative infection;
  • intraoperative cultures and cell count:
    • WBC count of less than 3000/?L indicates the absence of infection
    • WBC count of greater than 10,000/?L indicates the presence of an infection;
    • WBC cout of between 3000 and 10,000, base decision on the C-reactive protein level frozen section;
  • references:
    • Revision operations on infected total hip arthroplasties. Two- to nine-year follow-up study.
    • The value of aspiration of the hip joint before revision total hip arthroplasty.

Surgical Considerations

acetabular exposure »

• w/ hybrid THR, typically the femoral stem is first removed (to improve exposure) but the cement is left in place (to reduce blood loss);
• if exposure is not optimal, then consider trochanteric osteotomy;
• entire circumference of the acetabular component must be visualized;
• polyethylene is then removed (may be performed w/ corkscrew or with insertion of 6.5 mm screw thru the polyethylene and against the metal cup);
• if screws are present, these are removed;
• ref: A technique of revision of failed acetabular components leaving the femoral component in situ.

management of osteolysis »

• note that in cases of acetabular osteolysis, the metal cup will often will have fixed ingrowth into the acetabulum;
  • attempts to revise the component in these cases, may end up removing significant amounts of bone or may even risk fracture;
• references:
  • The fate of pelvic osteolysis after reoperation. No recurrence with lesional treatment.
  • Treatment of pelvic osteolysis associated with a stable acetabular component inserted without cement as part of a total hip replacement.

technique for cup removal »

• surgeon needs to have a "back up plan" if component removal results in acetabular fracture;
• references:
  • Sciatic neuropathy secondary to intrapelvic migration of an acetabular cup. A case report.
  • A technique for removing an intrapelvic acetabular cup.

protrusio »

• w/ mild protrusio, routine methods can be used to remove the acetabular component, but with severe protrusio consider an intrapelvic approach (to avoid vasular, nerve, and or bowel injury);
• reference:
  • Revision Total Hip Arthroplasty for Large Medial (Protrusio) Defects With a Rim-Fit Cementless Acetabular Component.

bone grafting of acetabular defects »

• management of pelvic discontinuity
• reference:
  • Dealing with the deficient acetabulum in revision hip arthroplasty.
  • Total Hip Arthroplasty in Patients with Bone Deficiency of the Acetabulum

Acetabular Component Insertion and Grafting Options

general considerations:

• need to determine the level of the true acetabulum;
  • homan retractor is placed in the obturator foramen as a reference for the inferior aspect of the acetabulum;
  • sequential reaming is carried out until the anterior and posterior columns are engaged by the reamer;
• non biologic fixation:
  • antiprotrusio cage: (w/ or w/o structural allograft);
  • impaction grafting with or without an antiprotrusio cage;
  • cemented polyethylene cup
  • superior structural allograft w/ cemented polyethylene cup;
  • total acetabular allograft;
• cementing a liner into a well fixed cup:
  • need to make sure that the polyethylene cup is smaller than the shell;
  • there needs to be at least some minimal roughness to allow for adequate cement fixation;
  • references:
    • A constrained liner cemented into a secure cementless acetabular shell.
    • A biomechanical analysis of polyethylene liner cementation into a fixed metal acetabular shell.
    • Cementation of a Polyethylene Liner into a Metal Acetabular Shell: A Biomechanical Study
    • Dislocation after polyethylene liner exchange in total hip arthroplasty.
    • Cementation of a polyethylene liner into a metal shell: Factors related to mechanical stability.
    • Cementing a liner into a stable cementless acetabular shell: the double-socket technique.
• biologic fixation:
  • needs direct contact w/ host bone and osseointegration into the acetabular shell in order to provide long-term fixation;
  • biologic fixation requires inherent stability of the implant;
  • bone grafting of acetabular defects
    • management of pelvic discontinuity
    • reference: Dealing with the deficient acetabulum in revision hip arthroplasty.
  • screw placement
    • fixation w/ multiple acetabular screws enhances stability and minimally sacrifices the remaining bone;
    • note that the quadrant system for safe screw insertion may not apply to a high hip center;
    • screws are placed posterosuperiorly into the dome of the acetabulum and also inferiorly into the ischium;
    • references:
      • Safe screw placement in acetabular revision surgery.
      • L5 radiculopathy secondary to intrapelvic placement of acetabular cup fixation screw.
      • Does Ischial Screw Fixation Improve Mechanical Stability in Revision Total Hip Arthroplasty?
  • press fit cup at anatomic vs high hip center:
    • press fit cup at a high hip center (>2 cm superior to the native hip center);
  • medial protrusio technique
  • rim fixation technique:
    • references:
      • Stability of Revision Acetabular Components Using the Rim-Fit Technique.
      • Revision total hip arthroplasty for large medial (protrusio) defects with a rim-fit cementless acetabular component.
      • Large Acetabular Defects Can be Managed with Cementless Revision Components
  • jumbo press fit cup (66 to 80 mm)
    • references:
      • Revision of failed acetabular components with use of so-called jumbo noncemented components. A concise follow-up of a previous report.
      • Treatment of large acetabular defects with jumbo cups.
      • Acetabular revision arthroplasty using so-called jumbo cementless components: an average 7-year follow-up study.
      • Jumbo cups and morsalized graft.
      • Dealing with the deficient acetabulum in revision hip arthroplasty: the importance of implant migration and use of the jumbo cup.
      • Jumbo cup or high hip center. Is bigger better?
      • The fate of cementless jumbo cups in revision hip arthroplasty.
      • Jumbo cups for revision of acetabular defects after total hip arthroplasty: a retrospective review of a case series
  • oblong cup / modular cup-and-augment system:
    • allows for less stripping of the ilium and less mobilization of the abductors;
    • allows for faster and easier procedure;
    • does not have the potential for resorption;
    • note potential for debris generation at the interface, potential for fatigue failure, and inability to restore bone stock for future revisions;
    • references:
      • The use of bilobed porous-coated acetabular components without structural bone graft for type III acetabular defects in revision total hip arthroplasty: a prospective study with a minimum 2-year follow-up.
      • Type III Acetabular Defect Revision With Bilobed Components: Five-Year Results
      • Reconstruction of major segmental acetabular defects with an oblong-shaped cementless prosthesis: a long-term outcomes study.
  • press fit hemispherical cup supported by structural allograft;
  • bipolar arthroplasty:
    • references:
      • Acetabular salvage in revision total hip arthroplasty using the bipolar prosthesis.
      • Reconstruction of the deficient acetabulum using the bipolar socket.

gap cup and reconstruction rings »

femoral component considerations »

• even with isolated acetabular revision, have available selection of company appropriate femoral heads;
• revision of the acetabular component will involve additional reaming which will tend to further medialize the acetabulum, which means that re-insertion of the old modular femoral head will leave the hip loose and unstable;
• it is expected that a femoral head with a larger neck length will be required;
• in the case of residual instability, a 32 mm head (and appropriate liner should be available);
• references:
  • Ten years of experience with porous acetabular components for revision surgery.
  • Acetabular augmentation in primary and revision total hip arthroplasty with cementless prostheses.
  • Revision Total Hip Arthroplasty with Cement after Cup Arthroplasty. Long-Term Follow-Up.
  • Acetabular preparation in cementless revision total hip arthroplasty.
  • Revision of the acetabulum without cement with use of the Harris-Galante porous-coated implant. Two to eight-year results.
  • The Fate of Revised Uncemented Acetabular Components in Patients With Rheumatoid Arthritis.
  • Cementless Acetabular Revision with the Harris-Galante Porous Prosthesis. Results After a Minimum of Ten Years of Follow-up.
  • Revision of the acetabular component without cement after total hip arthroplasty. A concise follow-up, at fifteen to nineteen years, of a previous report.

Post Op Radiographic Evaluation »

Examples

 

 

 

• example of an acetabular component that was obviously loose after 3 years;
  • at surgery, the femoral component was secure and was left in place;
  • the acetabulum was re-reamed for insertion of a larger component;
  • a cortical allograft was anchored to the lateral femur inorder to re-oppose the abductors

References

• Early Postoperative Transverse Pelvic Fracture: A New Complication Related to Revision Arthroplasty with an Uncemented Cup.
• Porous-Ingrowth Revision Acetabular Implants Secured with Peripheral Screws. A Minimum Twelve-Year Follow-up.