Distal femoral arthroplasty for native knee fractures results from the AustrAliAn orthopAedic AssociAtion nAtionAl Joint replAcement registry

Aims The aim of this study was to investigate the rate of revision for distal femoral arthroplasty (DFa) performed as a primary procedure for native knee fractures using data from the australian Orthopaedic association National Joint arthroplasty registry (aOaNJrr). Methods Data from the aOaNJrr were obtained for DFa performed as primary procedures for native knee fractures from 1 September 1999 to 31 December 2020. Pathological fractures and revision for failed internal fixation were excluded. The five prostheses identified were the Global modular arthroplasty System, the modular arthroplasty System, the modular universal Tumour and revision System, the Orthopaedic Salvage System, and the Segmental System. Patient demographic data (age, sex, and American Society of Anesthesiologists grade) were obtained, where available. Kaplan-meier estimates of survival were used to determine the rate of revision, and the reasons for revision and mortality data were examined. Results The AOANJRR identified 153 primary DFAs performed for native knee fractures in 151 patients during the study period, with 63.3% of these (n = 97) performed within the last five years. The median follow-up was 2.1 years (interquartile range 0.8 to 4.4). The patient population was 84.8% female (n = 128), with a mean age of 76.1 years (SD 11.9). The cumulative percent revision rate at three years was 10%. The most common reason for revision was loosening, followed by infection. Patient survival at one year was 87.5%, decreasing to 72.8% at three years postoperatively. Conclusion The use of DFa to treat native knee fractures is increasing, with 63.3% of cases performed within the last five years. While long-term data are not available, the results of this study suggest that DFa may be a reasonable option for elderly patients with native knee fractures where fixation is not feasible, or for whom prolonged non-weightbearing may be detrimental.