2025 COA Annual Meeting: Randomized Controlled Trial Comparing Tibial Baseplate Stability Between Anatomic (Femur-First) and Mechanical Alignment Techniques Using Radiostereometric Analysis

Fifty-seven patients with end-stage osteoarthritis undergoing total knee arthroplasty were randomized to receive either anatomical alignment (n=24) or mechanical alignment (n=22) using a fixed-bearing ATTUNE S+ Cruciate Retaining implant. The primary outcome was tibial baseplate subsidence at 12 and 24 months. Secondary outcomes included maximum total point motion (MTPM) and the effect of weight-bearing on stability. RSA imaging was performed at 6 weeks, 6, 12, and 24 months (supine), with additional standing imaging at 24 months. Overall, the results of the study revealed no statistically significant differences in tibial baseplate subsidence (p=0.727) or MTPM (p=0.460) between groups. These findings suggest that either alignment strategy can be used without compromising implant stability.