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posterior structures (facets and facet capsule, and posterior muscles and ligaments),proportionately increasing their mechanical advantage. Finally, the combined three lobe-in-disharticulation is at its lowest energy point when at rest in a neutral position. Any angular rotationresults in distraction, effectively moving against the axial loads imposed by gravity and muscleforce. This provides an important additional stabilizing influence on the TDR construct. Ageometric simulation was used to project the combined effects of this intrinsic “energeticstability” and cadaveric testing used to evaluate and compare its stability to a control ball-introughTDR.Results: The force-displacement diagram [Fig 2] shows the centering of the lowest energypoints for all physiological rotations and translations to reside at the neutral position for the Tri-Lobe articulation. The single non-physiologic component to this stabilizing kinematic effect isthat there is a slight degree of distraction of 0.7 mm. We have been unable to determine anydeleterious effect from this effect which otherwise contributes to stability. This stability andcoupling of motions was confirmed in cadaveric kinematic studies.Discussion: The Tri-Lobe TDR possesses intrinsic biomechanical stability as a result of severalcritical design elements. It has the potential to provide a platform for stable, multi-level discreplacement, while restoring normal kinematics.FiguresFigure 1 Figure 2Poster: 72The Impact of Launch Strategies on the Survivorship of New DevicesIntroduction*Philip Noble - Institute of Orthopedic Research and Education - Houston, USA*Email: pnoble@bcm.eduOne of the potential attractions of Joint Registries is early identification of defective implants.However, new technologies are often associated with a learning curve which necessarily leadsto inferior early results. This study examines the effect of different methods of introduction of anew implant on its early survivorship.Materials and MethodsWe modeled a database of 6000 operations performed using a new implant over a 5 year period.We assumed an average revision rate of 3.4% based on survivorship for hip resurfacing. Fourdifferent scenarios were modeled corresponding to the manner of introduction of this device tothe community. The "Standard" scenario assumed that 165 surgeons gradually adopted thefile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]