Assessing the Influence of Body Mass Index and Tibial Prosthesis Design Characteristics on Survivorship in Total Knee Arthroplasty

The purpose of the study was to determine the relationship between increased body mass index (BMI) and tibial prosthesis characteristics. A retrospective analysis of total knee arthroplasties (TKAs) was completed, and a Cox multivariate regression was performed. In total, 8,548 TKAs were completed, and cumulative survivability was 98.0% at 5 years and 97.1% at 10 years. Age < 70 years (p < 0.01), male sex (p < 0.01), and BMI ≥ 40 kg/m2 (p = 0.04) were significantly related to revision in all implants. Implant type, contact surface area, base plate surface area, and tibial stem length did not have a statistically significant effect on implant survivability (p = 0.62 – 0.91). When stratified based on BMI, there was a significant decrease in survivability for those BMI ≥ 40 kg/m2 (p < 0.01). Patients with high BMI do not necessarily require larger implants, and surface area and stem length do not affect survivability. Patient factors appear to drive survivability outcomes after primary TKA more than the implant factors. (Journal of Surgical Orthopaedic Advances 34(4):203–206, 2025)

Key words: total joint arthroplasty, body mass index, implant, tibial component, stem length