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Friday, October 8, 2010, 11:00-11:50Session B11: Knee MechanicsDesign Rationale and Clinical Evaluation of Total Knee ArthroplastyReproducing Anatomic Geometry for Asian*Toru Suguro - Toho University, School of Medicine - Tokyo, JAPANKeitaro Yamamoto - Toho University, Graduate School of Medicine - Tokyo, JAPANYoshiyasu Miyazaki - Toho University, School of Medicine - Tokyo, JAPANTakashi Nakamura - Toho University, School of Medicine - Tokyo, JAPANMasayuki Sekiguchi - Department of Orthopaedic Surgery, Toho University School ofMedicine - Tokyo, JAPANScott Banks - University of Florida - Gainesville, USA*Email: keitaro@med.toho-u.ac.jpAims: Recently, total knee arthroplasty (TKA) has been generalized as an operation thatachieves excellent clinical results. However, younger and Asian patients require even greaterimplant longevity and functional performance. We hypothesized a novel posterior cruciateretainingTKA design that restores the anatomical jointline in both sagittal and coronal planes,maintains the femoral posterior condylar offset, and provides low contact stress would provideenhanced patient function with the potential for greater implant longevity.Methods: The novel TKA design was created based on geometry determined from anatomicspecimens, 3-degree step of femorotibial jointline was incorporated in the TKA design forAsian. The novel TKA has an asymmetrical design between the medial and lateral femoralcondyle, the medial femoral condyle designed to be 3 degrees larger than the lateral femoralcondyle. It refined using finite element analyses (FEA) to minimize peak contact stresses. Thealignment evaluation after TKA was performed using using bidirectional CR and CT images.Femorotibial-angle (FTA), the position of the femoral component relative to the 3D mechanicalaxis, and the rotational alignment of the femoral component relative to the PC line wereevaluated before and after TKA to identify changes in the femoral condylar shape. Thekinematic evaluation after TKA was performed using a 3D-to-2D model registration technique.Single-plane fluoroscopic imaging was used to record and quantify the motions of knees duringa stair-step activity. The contact points between the tibiofemoral motions and the tibialrotational angle were evaluated.Results: FEA showed peak von Mises stress of 10.5 MPa under 2000 N load, well below thefile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]