Acetabular Component Revision - Wheeless' Textbook of Orthopaedics

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- acetabular component

- Discussion:
- 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:
- rule out infection:
- inaddition 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.
- extraction instruments:
- cell saver;

- 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. J. Arthroplasty. Vol 11. 1996. p 482-483.
- 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. TP Schmalzried MD. CORR 350. p 128-137. May 1998.
- Treatment of Pelvic Osteolysis Associated w/ a Stable Acetabular Component Inserted w/ Cement as Part of a THR. Maloney JBJS 79-A Nov 1997. p 1628.
- 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. ZU Isiklar MD et al. JBJS. Vol 79-A. No 9. Sep 1997. p 1395.
- A technique for removing an intrapelvic acetabular cup. P Grigoris et al. JBJS. Vol 75-B. (1) p 25-27. 1993.
- 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);
- references:
- Revision Total Hip Arthroplasty for Large Medial (Protrusio) Defects With a Rim-Fit Cementless Acetabular Component.

- Acetabular Component Insertion and Grafting Options:
- general considerations:
- non biologic fixation:
- antiprotrusio cage: (w/ or w/o structural allograft);
- cemented polyethylene cup:
                    - superior structural allograft w/ cemented polyethylene cup;
- impaction grafting with or without an antiprotrusio cage;
- total acetabular allograft;
- 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;
- 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);
- 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.
- Dealing with the deficient acetabulum in revision hip arthroplasty.
- Jumbo cup or high hip center. Is bigger better?
- The fate of cementless jumbo cups in revision hip arthroplasty.
- 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.
                                - Type III Acetabular Defect Revision With Bilobed Components
                                - Reconstruction of Major Segmental Acetabular Defects with an Oblong-Shaped Cementless Prosthesis: A Long-Term Outcomes Study
                                - Type III Acetabular Defect Revision With Bilobed Components. Five-year Results
                    - 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.
- bone grafting of acetabular defects:
- management of pelvic discontinuity:
- gap cup and reconstruction rings:
- 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;
- references:
- Safe screw placement in acetabular revision surgery.
- L5 radiculopathy secondary to intrapelvic placement of acetabular cup fixation screw.
- femoral component considerations:
- even with isolated acetabular revision, it is essential to have a selection of appropriate femoral heads available
(remember that the morise taper of femoral components is company specific);
- 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. JBJS Vol 78-A No 1., Jan 1996.
- 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. MA. Mont, MD. CORR 2002;2002:140-148
- 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.

- 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.