MID-TERM SURVIVORSHIP OF CEMENTED VERSUS CEMENTLESS TOTAL KNEE ARTHROPLASTY OF THE SAME DESIGN: A MINIMUM FIVE-YEAR FOLLOW-UP STUDY

Introduction The attention to biologic fixation has been growing over the past few years in total knee arthroplasty (TKA), due to the evolution of highly porous metals and improved implant designs. The aim of this study was to assess the mid-term survivorship of a modern cementless TKA design, as compared to its cemented counterpart. Methods We reviewed 261 cemented and 222 cementless primary TKAs that were performed at our institution between May 1, 2018 and May 31, 2019 using the same implant design. Demographic data, including age, sex, body mass index (BMI), and American Society of Anesthesiologists (ASA) score, were collected. We assessed survivorship and compared aseptic loosening, all-cause aseptic revision, and all-cause revision rate between groups. The presence of radiolucent lines was also evaluated on the most recent radiographs. Minimum follow-up was five years (mean, 5.8; range, 5.0 – 6.4 years). Results A total of four revisions occurred in the cemented group: two for periprosthetic joint infection, one for patellar maltracking, and one for stiffness. The cementless group had one revision, which involved patellar resurfacing for patellar degeneration. No cases of aseptic loosening were recorded in either group. All-cause revision rate for aseptic reasons was 0.8% in the cemented and 0.5% in the cementless cohort, with no difference between them ( P > 0.05). The 5-year all-cause revision survivorship was 98.5% in the cemented and 99.5% in the cementless group. Non-progressive radiolucent lines were observed in 28 (10.7%) cemented knees and in 22 (9.9%) cementless knees ( P > 0.05). No radiographic evidence of component subsidence was identified in either group. Conclusion Cementless fixation in TKA demonstrates excellent mid-term survivorship and radiographic outcomes; equivalent to those of cemented fixation. Longer-term follow-up is warranted, to further assess the durability of cementless implants and explore potential superiority of any of the fixation techniques.