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Discussion and Conclusion: Results of THA in patients less than 50 years using aluminaceramic-ceramic bearings at two to twelve years follow-up are promising with no case ofosteolysis or dislocation.Poster: 71TriLobe TDR Design Promotes Intrinsic Biomechanical Stability andPhysiologic KinematicsBao K.N. Nguyen - Dimicron, Inc - Orem, USA*Jeffery Taylor - Sacramento VA Medical Center - Loomis, USARichard Dixon - Dimicron, Inc. - Orem, USAGerman Loesener - Dimicron, Inc. - Orem, USADavid Harding - Dimicron, Inc - Orem, USAVaneet Singh - Dimicron, Inc. - Orem, USAA. Stan Despres - Dimicron, Inc. - Orem, USABill J. Pope - Dimicron, Inc. - Orem, USA*Email: jktaylor@pol.netIntroduction: The anatomic center or rotation (COR) for a spinal motion segment is not fixedand moves, as an instant COR, in a domain located inferior and posterior to the center of theintervertebral disc while load transmission is through the center of the disc. Current articulatingdesigns for TDR depend primarily upon a fixed center of rotation (COR). To maximize motion,the COR must be placed at the posterior disc space off the load transmission axis with atendency to fall into kyphosis. Stacking multiple TDR levels tends to result in furtherdeformities. The purpose of this study was to design and evaluate a TDR which restoredphysiologic kinematics while providing coaxial load support, and which was biomechanicallystable enabling stable multiple level TDR. The TriLobe [Fig. 1] is a radical cervical TDRdesigned with self-centering articulating geometry. It features three incongruent self-centeringhard-on-hard articulations arranged in a tri-pod configuration. The diameter and spacing oftheses articulations determines a kinematic envelope designed to match the 6D anatomic motiondata from published sources. It couples motion in a physiologic manner. In cadaver kinematicstudies presented last year, we demonstrated its reproduction of kinematics closely matching thenormal motion segment and demonstrated its tolerance to wide placement variations.Materials and Methods: The “tripod” structure of the Tri-Lobe TDR is a broad-based supportplatform around the center of axial load support through the vertebral body. Perturbations ofthis load axis within this zone will tend towards intrinsic stability. Placing the dual lobes on theanterior aspect serves doubly to prevent anterior/lateral kyphotic instability, and to mirrorposterior facet stability. With coupled motion, the dual anterior lobes move forward intranslation with flexion as a “moving fulcrum,” increasing the moment arm of the restrainingfile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]