Performance Comparison of Single-Radius Versus Multiple-Curve Femoral Component in Total Knee Arthroplasty: A...

Midflexion stability after total knee arthroplasty (TKA) is dependent, in part, on implant design. Midflexion performance of a single-radius (SR) design and a multi-radius, or J-curve (JC), design were compared using the Lower Quarter Y-Balance Test (YBT-LQ). Patient-reported outcomes and measures of physical performance were also compared. The authors hypothesized that the SR design would provide superior midflexion stability and, therefore, a greater reach distance in the YBT-LQ when compared with the JC design. Patients undergoing primary, unilateral TKA were prospectively enrolled and block randomized to receive either the SR (n=30) or the JC (n=30) implant. Patients reported outcome measures (Knee Injury and Osteoarthritis Outcome Score, Knee Society Score, and University of California at Los Angeles Activity Score), performed the YBT-LQ, and completed physical performance measures (walking speed, timed up-and-go test, and sit-to-stand test) before surgery and 1 year postoperatively. One year postoperatively, 40 patients (20 SR, 20 JC) were available for analysis. There were no significant differences between the groups regarding age, sex, body mass index, American Society of Anesthesiologists score, YBT-LQ results, or any other variable of interest. In both groups, significant improvements were observed for all variables of interest when compared from preoperatively to 1 year postoperatively. Implant type did not affect patient-reported or physical performance outcomes following TKA; however, patients showed significant improvement in most outcome measures by 1 year postoperatively. The significant limitations in strength and balance in this cohort of patients likely outweigh any subtle differences in implant design. [Orthopedics. 2017; 40(6):e1074-e1080.].