Intermedics Orthopedics, Inc.

Joseph S Skraba

Brian D Burkinshaw

Aaron A Hofmann

Richard E Jones

John D Vinciguerra

Lawrence D Dorr

A prosthetic knee with a tibial prosthesis comprising a baseplate and an articulating surface which pivots on the baseplate about an axis within a medial condylar compartment.

Tibial prothesis with pivoting articulating surface

A tibial prosthesis with independent medial and lateral baseplates. The baseplates can be coupled together for simultaneous implantation using an implantation apparatus. A high-molecular weight polyethylene upper part with articulating surface can then be attached both to the baseplates and to the tibia. The resulting prosthesis can conform to the stabil condition of the tibia without rocking in the baseplates. Bony ingrowth from the tibial head into special surfaces of the baseplates securely attaches the baseplates to the tibial head and the possibility of diminished fixation is reduced.

Tibial prosthesis with independent medial and lateral baseplates

A surgeon-assemblable asymmetric tibial prosthesis with a snap-in tibial insert for surface replacement of the proximal tibia. The tibial prosthesis, consisting of two parts, a baseplate and a right or left knee specific insert, is used in conjunction with prosthetic femoral and patellar components. Asymmetry is created by having the radius which describes the medial condyle slightly greater, preferably 1/8', than the radius describing the lateral surface. The baseplate exhibits symmetry about an anterior/posterior centerline, allowing it to be used on right or left proximal tibias by rotation of the component 180.degree. about the centerline. The insert is contoured to provide an anatomically correct surface which articulates with the condyles of the femoral prosthesis. The anatomic fit contributes to normal range of motion since there is less chance of lateral overhang to cause soft tissue impingement. The increased cortical rim contact permits direct load transfer to the stronger cortical bone. In the preferred embodiment, two fully threaded bond screws secure the baseplate to the tibial bone surface and four pegs project from the inferior baseplate surface into the areas of the strongest tibial cancellous bone to provide torsional stability and reduce shear stress at fixation interfaces.

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Austin, TX, United States of America

Joseph S Skraba