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




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.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Monday, November 2, 2015 7:45 am