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Revision TKR: Revision of 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 patellar component is to be retained, then it is necessary to surgically remove the peripatellar "meniscal" tissue that typically
                  grows around 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 patellar rim to contain cancellous bone graft inserted into
                            patellar bone defect;
                  - follow-up was at a mean of 36.7 months (24 to 55 months) after the patellar bone-grafting procedure;
                  - mean preop 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.   

- references: 
      - Secondary Patellar Resurfacing as a Rescue for Persistent Anterior Knee Pain after TKA. Do Our Patients Really Improve?
      - Secondary resurfacing of the patella for persistent anterior knee pain after primary knee arthroplasty. 
      - Fate of the unrevised all-polyethylene patellar component in revision total knee arthroplasty. 
      - Isolated revision of the patellar component in total knee arthroplasty. 
      - Revision of failed patellar components.
      - Patellar component resection in revision and reimplantation total knee arthroplasty.
      - The Effect of Stuffing the Patellofemoral Compartment on the Outcome of Total Knee Arthroplasty 

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