Contemporary Cementless Patellar Implant Survivorship: A Systematic Review and Meta-Analysis of 3005 Patellae

Introduction: Historically, cementless patellar implants were fraught with issues of fixation and polyethylene wear. However, contemporary cementless patellar implants incorporate modern technologies for implant design and offer the potential for improved biological fixation and longevity. As such, an evaluation of the performance of modern cementless patellae is needed. The purpose of this study was to perform a systematic review and meta-analysis of contemporary cementless patellar implants used during primary total knee arthroplasty (TKA), with a particular focus on aseptic loosening of the patellar component. Material and methods: A systematic review of the literature from January 2000 to February 22, 2024, was performed. We included all peer-reviewed studies that reported number of revisions in patients who had cementless patellae placed in 2000 or later during primary TKA. Reviews and case reports were excluded. Out of 639 studies, 13 studies were included with a total of 3005 cementless patellae analyzed. The mean patient age was 64 years and mean body mass index (BMI) was 31 kg/m2. Meta-analyses were performed to calculate pooled revision rate per person-year of revision for aseptic loosening of the patellar component and revision for any patellar failure. Results: Upon analysis of 13 studies involving a total of 3005 cementless patellae, the revision rate for aseptic loosening of the patella was 0.2 per 1,000 person-years and the revision rate for any patellar failure was 1 per 1000 person-year. Conclusions: Contemporary cementless patellar implants showed an overall revision rate of 1 per 1000 person-year, demonstrating excellent longevity. The high survivorship, together with a low rate of loosening, show the utility and effectiveness of these implants. Given the nature of biologic fixation, these results are promising for long-term implant stability, but additional follow-up is warranted. Keywords: cementless patella, metal-backed patella, total knee arthroplasty