Patellar fractures are associated with an increased risk of total knee arthroplasty

Abstract

Aims The aim of this study was to investigate the incidence of knee arthroplasty and arthroscopy following patellar fractures, and to compare this with an age- and gender-matched group without a prior patellar fracture. Patients and Methods A national matched cohort study based on the Danish National Patient Register including all citizens of Denmark (approximately 5.3 million) was undertaken. A total of 6096 patients who sustained a patellar fracture in Denmark between 1 January 1996 and 31 December 2000 were included. The median age of these patients was 50.6 years (interquartile range (IQR) 28.5 to 68.9); 49.1% were women. Patients were followed-up until 31 December 2015, with regard to treatment with knee arthroplasty and/or knee arthroscopy. Results Patients with a patellar fracture had an increased risk of knee arthroplasty (hazard ratio (HR) 1.83, 95% confidence interval (CI) 1.57 to 2.13) compared with citizens without a patellar fracture, and the effect was strongest during the first five years (HR 3.02, 95% CI 2.26 to 4.03). Patients with a patellar fracture also had a higher risk of knee arthroscopy (HR 3.94, 95% CI 3.49 to 4.46), and the effect was highest during the first five years after the fracture (HR 7.40, 95% CI 6.32 to 8.66). Conclusion Patellar fractures are associated with an increased risk of knee arthroplasty and knee arthroscopy. The consequences of a patellar fracture may be more severe than previously considered, and patients must expect a lifelong increased risk of knee arthroplasty. Cite this article: Bone Joint J 2018;100-B:1477–81.