- See:
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Total Hip Replacement Menu:
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Acetabular Component Revision:
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Femoral Bone Grafting for THR:
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Frozen Allograft
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Dysplastic Hip:
- Discussion:
- in planning of acetabular reconstruction, major goal is to establish normal anatomic center of rotation;
- key to preventing migration is getting fixation on acetabular periphery;
- block allografts or autografts may be essential to provide proper prosthetic support;
- secure graft fixation with maximum contact of graft to a bleeding host surface is important for appropriate healing and support;
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Paprosky classification:
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descriptive classification of defects:
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cavitary deficiencies
- the
anterior and
posterior columns and peripheral bone is intact;
- skeleton is intact and therefore these defects are easier to deal with than segmental defect;
- defects should be filled with graft;
- particulate graft is reversed reamed to pack evenly into defects;
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segmental defects:
- segmental defects are repaired w/ structural grafts;
- if sufficient bone is available from iliac crest & shaped to replace absent bone;
- central (medial wall absent)
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pelvic descontinuity:
- Operative Strategy:
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component fixation without bone graft:
- if no more than 30-40 % of the surface of the acetabular component remains uncovered, then application of bone graft may not be necessary;
- the graft may be inserted without cement, and an acceptable amount of bone ingrowth may be expected to occur;
- if there is more than 50% uncoverage or pelvic discontinuity, then consider inserting a cemented acetabular cup (or
gap cup);
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morselized bone graft:
- can be used to help recreate bone stock w/
protrusio, cavitary, or medial wall deficiency;
- cannot be expected to provide ingrowth or stability, but over time the morselized graft can undergo revascularization and remodeling;
- antiprotrusio cage or
gap cup is then placed over the graft;
- references:
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Cortical and cancellous morselized allograft in acetabular revision total hip replacement. Minimum 5-year follow-up
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Acetabular reconstruction with a bipolar prosthesis and morseled bone grafts.
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Morselized allograft in acetabular reconstruction. A postmortem retrieval analysis.
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structural bone grafts:
- structural bone grafts and cemented prosthesis may be indicated when there is less than 50% of acetabular contact;
- as pointed out by Hasegawa et al 1996, when there was more than 67% of acetabular coverage in dysplastic hips, there were no revisions at 13 years;
- it has been recommended that w/ 60% to 70% coverage, structural bone grafts are not necessary;
- if structural bone grafts support more than 50 per cent of the cup, then is should be protected with a
reconstruction ring;
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operative technique for superior structural bone grafting:
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frozen allograft preparation;
- acetabular floor is cleared of scar and soft tissue;
- frozen allograft is thawed and shaped to fit the acetabular defect; (distal femur is often allograft of choice);
- frozen allograft is thawed, cultures are taken, and graft is placed in 50 per cent Betadine (povidone-iodine) solution;
- allograft is rinsed with a mixture of one-third 3 per cent hydrogen peroxide and two-thirds saline solution and then is rinsed with bacitracin;
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minor column graft: (see
regenerex)
- by definition minor column allograft (shelf graft) will support less than 50 per cent of the cup;
- size and shape of the graft are determined with a trial cup in place;
- cut surface of allograft is not placed in contact with host soft tissue in order to minimize resorption.
- graft is fixed with two 4.5-millimeter cancellous-bone screws;
- cup can be inserted either with or without cement;
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major column graft: (by definition supports greater than 50 percent of cup surface);
- graft is shaped to fit the acetabular defect; (distal femur is often allograft of choice);
- femoral head grafts should either be from males or premenopausal female donors;
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distal femoral bulk graft:
- distal aspect of a femur is sculpted to duplicate an acetabulum;
- distal femoral allograft with the attached metaphysis was cut into the shape of the number 7;
- condyles are reamed to accept an acetabular cup;
- anterior femoral groove and a portion of the metaphysis were positioned outside of the acetabulum, and positioned against the ilium;
- metaphysis side provides bone for internal fixation to the ilium;
- remainder of the femoral condyle is placed inside the acetabulum to buttress the ilium;
- after screw fixation, reaming is carried out in the usual manner until anterior and posterior columns are encountered;
- ref:
The Use of Structural Distal Femoral Allografts for Acetabular Reconstruction.
- bulk allograft should be butressed within the host acetabular defect rather than applied on the lateral wall of the ilium;
- align the graft trabeculae along the wt bearing axis;
- attempt to butress the graft with the posterolateral portion of the acetabulum;
- cancellous surface of the graft is not positioned against host soft tissue because this allows
more rapid resorption than the subchondral bone surface;
- cancellous surface should face the cup;
- drill small holes in the ilium where it abuts the shelf graft inorder to encourage union and remodeling;
- contouring is carried out inorder to maximize contact between host and allograft surfaces;
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fixation:
- if pelvic discontinuity exists, then
posterior column plating is performed prior to fixation;
- depending on the size of the graft use at least two
4.5 or 6.5 cancellous lag screws placed over washers;
- screws need to be placed parallel to each other and along the wt bearing forces;
- screw threads should be in the host bone and not in the graft;
- screw placement should not interfere with component placement;
- use of a acetabular reconstruction ring and cement may be key elements of long term success found in some series;
- if more than 50% of the socket is involved, the cup will have to be cemented;
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reaming:
- following application of the graft, reaming is performed in the usual manner;
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results of structural grafting:
- historically, non-contained defects of the acetabular column which involve more than 50% of the acetabulum have had mixed results;
- when graft coverage is less than 30%, results are markedly improved;
- many are pesimistic about the fate of massive allografts applied to the acetabulum w/o cement;
- main mode of failure of bone grafts (esp allografts) occurs as a result of collapse and graft resorption;
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complications of bulk grafts:
- clinical failure:
- structural acetabular allografts may fail in 50% of cases at 10 years;
- failure of autogenous graft to unite w/ host bone;
- success of graft fixation is directly related to amount of contact area;
- w/ autogenous femoral head grafts, success of graft fixation appears to diminish significantly when contact area is less than 50%;
- at 16 years, less than 20% of these grafts will be rigidly fixed;
- in contrast, when contact area is more than 70% there is a high success rate of graft fixation;
- hence, the hip revisions that require bulk grafts for fixation (ie lack of contact), will be at the highest risk of graft failure;
- resorption of the graft (determined by comparing recent radiographs with radiographs taken immediately postop);
- 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;
Failure of acetabular autogenous grafts in total hip arthroplasty. Increasing incidence: a follow-up note.
The fate of acetabular allografts after bipolar revision arthroplasty of the hip. A radiographic review.
Fate of bone grafts in acetabular roof reconstructions assessed by roentgenography and scintigraphy.
Revision of the Acetabular Component of a Total Hip Arthroplasty with a Massive Structural Allograft.
D. Garbuz M.D., E. Morsi, and A.E. Gross M.D. JBJS 78-A No. 5, May 1996.
Total Hip Replacement with Insertion of an Acetabular Component without Cement and a Femoral Component with Cement.
C.G. Mohler, L.R. Kull, J.M. Martell, A.G. Rosenberg, and J.O. Galante MD. JBJS. Vol-A 77-A No. 1 Jan. 1995.
Autogenous bone grafts from the femoral head for the treatment of acetabular deficiency in primary total hip arthroplasty with cement. Long-term results.
Femoral head autografting to augment acetabular deficiency in patients requiring total hip replacement. A minimum five-year and an average seven-year follow-up study.
Noncemented acetabular revision arthroplasty using allograft bone.
Allograft reconstruction of the acetabulum during revision total hip arthroplasty. Clinical, radiographic, and scintigraphic assessment of the results.
Acetabular augmentation in primary and revision total hip arthroplasty with cementless prosthesis.
FR Covery et al. CORR. Vol 252. 1990. p 167-175.
Acetabular Revision Options.
JC McCarthy MD et al. Orthopedics. Sep 1998. Vol 21. No 9. p 1002.
Bipolar components for severe periacetabular bone loss around the failed total hip arthroplasty.
Treatment of type III acetabular deficiencies in revision total hip arthroplasty without structural bone-graft.
Classification and reconstruction in revision acetabular arthroplasty with bone stock deficiency.
A comparison of the reliability and validity of bone stock loss classification systems used for revision hip surgery.
Management of massive acetabular defects in revision total hip arthroplasty.
Acetabular defect classification and surgical reconstruction in revision arthroplasty. A 6-year follow-up evaluation.
Use of structural allografts in acetabular revision surgery.
Principles of bone grafting in revision total hip arthroplasty: Acetabular technique. COOR 1994; 298: 147-155.
The fate of acetabular allografts after bipolar revision arthroplasty of the hip. A radiographic review.
Noncemented acetabular revision arthroplasty using allograft bone.
Principles of bone grafting in revision total hip arthroplasty. Acetabular technique
