Anatomical fit of the oneKNEE tibia design using statistical shape modeling

Modern tibial implants should be designed to achieve an optimal anatomical fit. The aim of this study was to evaluate how well a newly developed tibial implant design (oneKNEE® - B. Braun Aesculap, Tuttlingen, Germany) matches patient anatomy compared to three existing implant systems, using Statistical Shape Models (SSM).

SSMs for Caucasian and Asian populations were generated using CT scans of 120 Caucasian and 112 Asian osteoarthritic patients. Border anatomical variations were represented by individual anatomies from 14 Caucasian and 12 Asian patients. Tibial components were positioned in accordance with strict protocols established by senior knee surgeons (YM, NK). The anatomical fit was analyzed across all four implant systems in terms of antero-posterior and medio-lateral dimensions, tibial coverage and cortical bone support. Global tests for homogeneity and Dunnett's tests were performed.

Bony coverage for Asian and Caucasian populations ranged from 82.9% to 88.4% for long-established designs and from 85.0% to 91.2% for more recently introduced designs. Among all designs, the oneKNEE® implant demonstrated superior bony coverage and cortical support, followed by Attune® (Depuy-Synthes, Warsaw, IN, USA), Columbus® (B. Braun Aesculap), and PFC Sigma® (Depuy-Synthes). For average anatomies, oneKNEE® showed significantly better bony coverage and cortical score compared to Columbus® and PFC Sigma® (P < 0.01). In less average anatomies, oneKNEE® exhibited statistically superior bony coverage compared to PFC Sigma®, although no significant difference was observed in cortical support.

Compared with established tibial implant designs, the new design demonstrated improved virtual anatomical fit and coverage metrics based on computational modeling. These findings reflect a theoretical design‑level improvement and require biomechanical and clinical validation.