Functional Outcomes Used to Compare Single Radius and Multiradius of Curvature Designs in Total Knee Arthroplasty

A recent development to better recreate joint kinematics has been a change from a multiradius (MR) design to a single radius (SR) design. We analyzed 559 primary total knee arthroplasty (TKA) procedures which used either a SR (n = 426 Triathlon (R); Stryker Orthopaedics, Mahwah, NJ) or MR of curvature knee system (n = 133 Duracon (R); Stryker Orthopaedics, Mahwah, NJ) (79.3% follow-up; 705 total TKA procedures identified). Patients were administered a modification of the Knee Society score (KSS) (3.9 years average follow-up). The SR design showed improvements over the MR design in pain (p = 0.021), stability (p = 0.002), flexion (p = 0.006), ability to completely straighten the knee (p = 0.025), stair climbing (p = 0.0001), walking (p = 0.0001), use of assistive devices (p = 0.0005), postoperative knee score (p = 0.0005), and postoperative function (p < 0.0001). Analysis of the change in KSS knee (p = 0.002) and function scores (p = 0.002) from preoperative visit to postoperative follow-up favored the SR design as well. These data support the use of SR implants and provide evidence of improved outcomes in terms of function, stability, and pain.