Revision of a failed patellofemoral arthroplasty to a total knee arthroplasty

Background: Patellofemoral arthroplasty is an effective treatment for isolated arthritis of the anterior compartment of the knee, but it is unclear whether it compromises the results of total knee arthroplasty if revision is necessary. The purpose of this study was to review the results of total knee arthroplasty after a prior patellofemoral arthroplasty. Methods: Twelve failed patellofemoral replacements in ten patients were revised to total knee arthroplasties for isolated progressive tibiofemoral arthritis (six knees), isolated patellofemoral catching and maltracking (three), or a combination of both (three). Revisions were performed at a mean of four years after the patellofemoral arthroplasty. A posterior stabilized implant was used in each knee, without a need for stems, augments, or structural bone graft. Patients were assessed by clinical and radiographic follow-up, including Knee Society clinical and functional scores. Baseline preoperative Knee Society scores were obtained at the time of evaluation of the failed patellofemoral arthroplasty. Results: At a mean follow-up of 3.1 years, the mean Knee Society clinical and functional scores had increased from 57 points preoperatively to 96 points and from 51 points preoperatively to 91 points, respectively. At the most recent follow-up, there was no clinical or radiographic evidence of patellofemoral maltracking, loosening, or wear. Conclusions: On the basis of our experience in this relatively small series with short-term follow-up, the results of total knee arthroplasty do not seem to be compromised after revision of the failed patellofemoral replacement. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.