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Tibial prosthesis with asymmetric articular surfaces

  • US 7,625,407 B2
  • Filed: 02/07/2006
  • Issued: 12/01/2009
  • Est. Priority Date: 02/07/2006
  • Status: Active Grant
First Claim
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1. In a tibial prosthesis having tibial articular surfaces extending between an anterior edge of the tibial prosthesis and a posterior edge of the tibial prosthesis for enabling relative rotation between the tibial prosthesis and a femoral prosthesis engaged with the tibial prosthesis about a longitudinal axis of rotation during flexion of a prosthetic knee about a transverse axis, the tibial articular surfaces including a medial articular surface in a medial compartment and a lateral articular surface in a lateral compartment, an improvement wherein:

  • the medial articular surface follows a first arcuate track having a first radius of curvature extending from a corresponding center on a corresponding longitudinal axis and a first posterior segment extending along a posterior aspect of the medial compartment to a first point located adjacent the posterior edge of the tibial prosthesis and placed at a first inferior-superior location;

    the lateral articular surface follows a second arcuate track having a second radius of curvature extending from a corresponding center on a corresponding longitudinal axis and a second posterior segment extending along a posterior aspect of the lateral compartment to a second point located adjacent the posterior edge of the tibial prosthesis and placed at a second superior-inferior location;

    the second posterior segment follows a slope descending in an inferior direction relative to an anterior-posterior plane normal to a coronal plane and normal to a sagittal plane as the second posterior segment extends in a posterior direction along the posterior aspect of the lateral compartment such that the second superior-inferior location is placed at a predetermined distance in an inferior direction relative to the placement of the first superior-inferior location, thereby enabling the relative rotation between the tibial prosthesis and the femoral prosthesis along the first and second arcuate tracks to mimic corresponding kinematics of a natural knee; and

    the first posterior segment and the second posterior segment each extend along corresponding segments of a common helical path having a pitch for establishing the predetermined distance between the placement of the first and second superior-inferior locations.

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