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Dual-radius Glenoid Component for Total Shoulder Arthroplasty (HSS-0057)

HSS Innovation

Office of Technology Transfer,
Hospital for Special Surgery


DESCRIPTION: In total shoulder arthroplasties there are two main approaches regarding the amount of constraint desired between the components: (1) the surfaces of the components are not conforming and have less constraint, and (2) they are completely conforming surfaces where the contact stresses between the components are reduced, and there will be less wear of the components. Both approaches have problems: the first is less stable and more prone to dislocations, and the latter is vulnerable to component loosening.

The present invention is a design that combines the advantages of both approaches by having an articulating surface that has two radii of curvature. At the center of the surface, where it would be desirable for the design to be less constrained, the design has a larger radius of curvature, whereas at the periphery the radius is reduced to more closely match the radius of the humeral component. In this way as the humeral head moves towards the periphery the constraint on the design will increase. The constraint is applied when needed, not when the joint is nearly centered. When the joint is nearly centered, there will be minimum constraint on the design, and less shear load will be transferred to the bone-implant interface. With this new design, the force required to dislocate the device is greater than the non-conforming design, yet the constraint is identical to the non-conforming design for small translations.

ADVANTAGES: This new design is more similar to the natural shoulder anatomy.

STAGE OF DEVELOPMENT: Patent application filed, and patent protection is available throughout the world.

posted 4/22/2002