Classification and Outcomes of 214 Periprosthetic Patellar Fractures in Primary Total Knee Arthroplasty.

Abstract

Long-term data following periprosthetic patellar fractures around primary total knee arthroplasty (TKA) are lacking. The purpose of this study was to describe the classification, management, and outcomes of periprosthetic patellar fractures in, to our knowledge, the largest series to date. We identified 214 (213 cemented and one uncemented) periprosthetic patella fractures (205 patients) around a primary TKA sustained between 1989 and 2020. There were eight intraoperative fractures and 206 postoperative fractures. Postoperative fractures were classified according to the Ortiguera and Berry classification. There were 76% Type I fractures, 12% Type II fractures, 6% Type IIIA fractures, and 6% Type IIIB fractures. The mean patient age was 66 years (range 22 to 90), 56% were men, and their mean body mass index (BMI) was 32 (range, 21 to 54). The mean patient follow-up was seven years (range, two to 19). The incidence of intraoperative patellar fracture was 0.02%, occurring most frequently during exposure, implant preparation, or trialing (75%). The 10-year survivorships free of any revision and any reoperation after intraoperative fractures were both 88%. Among the 206 postoperative fractures, the majority (66%) occurred atraumatically, while 31% occurred after ground level falls. Among postoperative fractures, the 10-year survivorship free of any revision and any reoperation was 71 and 61%, respectively. Revision and reoperation risk after postoperative fracture varied by Ortiguera and Berry classification. The 10-year survivorship free of any revision was highest in Type I (80%) and significantly lower in Type II (60%) fractures. Compared to Type I fractures, survivorship free of revision was decreased in Type II (hazard ratio (HR) 8.4, P < 0.001), Type IIIA (HR 17.0, P < 0.001) and Type IIIB (HR 8.1, P < 0.001) fractures. Mortality following postoperative periprosthetic patellar fractures was 7% at two years and 55% at 10 years. Intraoperative periprosthetic patellar fractures during primary TKA were rare and generally well-tolerated. Ortiguera and Berry Types II and III fractures were associated with the highest risk of revision and reoperation.