Importance

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Abstract

The present invention provides tools and methods for mapping and measuring the articular surface of a joint (or of any bony surface) and for fabricating a prosthetic device based on this recorded data. In one embodiment, once the defect of the chondral surface has been identified, a guide pin is inserted arthroscopically. A fixation screw is driven into the subchondral bone in relation to a reference axis that is approximately central to the defect, the fixation device also serving to define a tangent point to the surrounding articular surface. A further cylindrical proximal extension of the screw that eventually serves as a fixation element for the surface prosthetic is concealed with a cover or plug. The depth positioning of the cover or plug establishes an origin or reference point for all future measuring, cutting, and prosthetic machining operations. A measuring tool having a static post that establishes the axial location of origin is inserted on the reference axis. By rotating the outer arm or outrigger of the measuring tool relative to the static post while also maintaining contact with the articular surface, an axial displacement or Z dimension is established relative to the origin for any point along the known radial sweep of the outrigger to determine the final geometry of the prosthetic surface which fits within the defect. Data recorded during the mapping procedure is entered into parametric engineering design software or similar algorithm to define a three dimensional surface matched to the bearing surface geometry to be implanted and reproduce the anatomic contours mapped.

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First Claim