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Revision Total Knee Replacement:

Revision Total Knee Arthroplasty

                                                                                                       - Assistance provided by Michael Berend MD

- PreOperative Considerations and Implant Selection:
    - work up of the painful TKR:

- Surgical Approach: (Surgical Approach for Primary TKR); 

 - Component Removal:
    - prior to component removal, take the knee thru a range of motion and evaluate patellar tracking and evaluate knee stability in extension, mid-flexion, and full flexion;
           - it is important to consider patellar tracking, since this will affect final rotation of the femoral component;
           - if their is optimal patellar tracking, then the surgeon should accept the orientation of the pre-existing femoral bone cuts;
    - it is important to know the status of pre-existing flexion and extension gaps before the components are removed,
           since this will have a bearing on anterior-posterior translation of the femoral medullary stem (and component);

 - Tibial Preparation:
    - remove 1-2.mm of bone using the intramedullary guide.
    - be aware of the preoperative flexion stability and ROM in choosing posterior slope;
    - for example, if the knee was unstable in flexion preoperatively, 0 degrees posterior slope may help reduce some of the flexion gap;
    - reaming for medullary stems:
           - after reaming to 12 mm, continue to procede slowly by 1 mm increments;
           - reaming should cease once firm resistance is encountered;
           - it is not necessary to have direct cortical contact, inorder to avoid excessive bone loss;
           - generally, stem diameter will be the same size as the reaming diameter;
    - debridement of remaining membrane debri:
           - all reactive membranes need to be removed;
    - insertion of trial tibial component:
           - place an appropriately sized tibial component and stem;
           - keep this component in position during femoral preparation;
           - typically it will be necessary to insert intra-medullary stems;
           - it is essential that the intra-medullary stem be inserted centrally in the medullary canal, which may or may not conform to the center of the cut tibial surface;
           - if there is a descrepancy between central medullary rod position and an optimally positioned tibial joint surface, the difference is made up w/ tibial wedges;
                   - the tibial surface may have to be recut to conform to the wedges;

 - Femoral Preparation

 - Cement Considerations:
    - before the cement is mixed, clearly note areas of minor bone defects (between the trial components and bone), and plan to add additional cement to these areas;
    - before the cement is mixed, ensure that all components are laid out on the table;
    - cementing technique:
          - apply cement to only condylar surfaces if press-fit stems are being used;
          - cement is applied to cut medullary surfaces, but in most cases cement is not placed into the medullary canal;
                - if stems are being cemented, consider use of a cement plug and an injection gun;
    - addition of antibiotics to cement
                - in some patients, consideration the addition of antibiotics to cement:
                      - indicated if there are additional risk factors for infection;
                      - generally, either 600mg tobramycin or 500mg vancomycin is added per 40g bag of cement;
    - ref: Stem fixation in revision total knee arthroplasty: a comparative analysis.

 - Insertion of the Patellar component:
    - one should consider not resurfacing the patella if less than 12mm of native bone remains (fx or early loosening may result);
           - obviously, if sepsis is present then patellar component removal is required;
           - if the patellar component is to be retained, then it is necessary to surgically remove the peripatellar "meniscal" tissue that typically grows around the patellar component;
                  - subsequently ensure that there is no patellar loosening;
           - finally if the patellar component is to be retained, there should be good compatibility with the revision femoral component;
    - some suggest sewing a remnant of the patellar fat pad into the patella if it  is not resurfaceable;
    - revision patellas are thicker to make up for lost bone and have shorter pegs;
    - if a primary patellar component is having its peg shortened for use in a revision situation, cut the peg with an oscillating saw away from the wound to prevent a shower of polyethylene particles;
    - following revision, the patellar height should be around 24-26 mm;
           - in the report by Hanssen AD, the author describes the surgical technique and early clinical results of an alternative to the conventional treatment options of either patellectomy or retention of the remaining patellar osseous shell;
                  - goals of this procedure were to restore patellar bone stock and potentially to improve the functional outcome;
                  - surgical procedure involves creating a tissue flap secured to the patellar rim to contain cancellous bone graft inserted into the patellar bone defect;
                  - final follow-up was at a mean of 36.7 months (range, twenty-four to fifty-five months) after the patellar bone-grafting procedure;
                  - mean preoperative Knee Society scores for function and pain were 39 points (range, 18 to 82 points) and 40 points (range, 20 to 80 points), respectively;
                  - at the time of final follow-up, the Knee Society function and pain scores had improved significantly, to a mean function score of 91 points (range, 80 to 98 points) and a mean pain score of 84 points (range, 65 to 100 points) (p < 0.05).
                  - point of greatest patellar thickness measured intraoperatively ranged from 7 to 9 mm.
                  - patellar thickness on immediate postoperative Merchant radiographs averaged 22 mm (range, 20 to 25 mm) whereas, at the time of final follow-up, patellar thickness averaged 19.7 mm (range, 17 to 22.5 mm).
                  - ref: Bone-Grafting for Severe Patellar Bone Loss During Revision Knee Arthroplasty.  

 - Complications:
    - infection:
           - may occur in 4% of patients (which is roughly 10 time higher than should occur in primary knees);
    - early failure:
           - component survivorship is roughly 80% at 8 years;
           - good to excellent results occur 50-80% of the time with complications occurring 15-30%;
           - wound comlications should be handled aggressively with skin graft, gastrocnemius flap or free flap;

- Postoperative Rehabilitation:
    - quadriceps snip can be rehabilitated routinely
    - quadriceps turndown or tubercle osteotomy requires no ROM for 2 weeks and no active extension for 2-6 weeks

 Results of revision total knee arthroplasties using condylar prostheses. A review of fifty knees.

A comparison of primary and revision total knee arthroplasty using the kinematic stabilizer prosthesis.

Hinged knee replacement in revision arthroplasty.

Femoral cement removal in revision total hip arthroplasty. A biomechanical analysis.

Revision knee arthroplasty in rheumatoid arthritis.

Revision of septic total knee arthroplasty.

Bone grafting and noncemented revision arthroplasty of the knee.

Revision total knee arthroplasty.

The results of revision total knee arthroplasty.

Revision total knee arthroplasty for aseptic failure.

Management of intraoperative femur fractures associated with revision hip arthroplasty.

Results of revision total knee arthroplasty performed for aseptic loosening.

Cementless reconstruction of massive tibial bone loss in revision total knee arthroplasty.

Massive allografts in salvage revisions of failed total knee arthroplasties.

Results of revision total knee arthroplasty associated with significant bone loss.

Isolated patellar component revision of total knee arthroplasty.

Reconstruction of major segmental loss of the proximal femur in revision total hip arthroplasty.

Principles of bone grafting in revision total hip arthroplasty. Acetabular technique.

Amputation after failed total knee arthroplasty.

Revision total knee arthroplasty with use of modular components with stems inserted without cement.

Mechanisms of failure of the femoral and tibial components in total knee arthroplasty.

Reoperation after condylar revision total knee arthroplasty

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