The spherocentric knee: biomechanical testing and clinical trial.

The spherocentric knee is a non-hinged, intrinsically stable knee-joint prosthesis which allows controlled triaxial rotation and was designed specifically for use in severely deformed or grossly unstable knees. Biomechanical evaluation of the prosthesis implanted in fresh human cadaver limbs demonstrated highly favorable motion, stability, strength, deflection, and energy absorption characterists for the spherocentric prosthesis-bone assembly as compared with control cadaver knees. After an average follow-up of 25.5 months after the first twenty-five spherocentric arthroplasties, the clinical results were highly satisfactory and suggested that the spherocentric knee may be relatively resistant to the problems of wear debris, loosening, and breakage which have plagued other intrinsically stable knee-joint prostheses.