Instruments and methods for locating a femoral mechanical axis
AssigneeOrthopaedic International, Inc.
InventorsJude L. Sasing, Ramon B. Gustilo
Life of this patent
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Abstract
An instrument for locating a femoral mechanical axis and identifying the locations of at least three points in space in relation to the center of a femoral head, the instrument including a base member, an extension arm clamp translationally and pivotally attached to the base member, an extension arm translationally and pivotally attached to the extension arm clamp, a swiveling arm pivotally attached to a distal end of the extension arm, the swiveling arm including a lateral locator member at a proximal end and a medial locator member at a distal end, a bracket pivotally attached to the swiveling arm, and a locating arm removably attached to the bracket, the locating arm including a middle locator member.
Claims20
An instrument for locating a femoral mechanical axis and identifying the locations of at least three points in space in relation to the center of a femoral head, the instrument comprising:
- a base member;
- an extension arm clamp translationally and pivotally attached to the base member;
- an extension arm translationally and pivotally attached to the extension arm clamp;
- a swiveling arm pivotally attached to a distal end of the extension arm, the swiveling arm comprising a lateral locator member at a proximal end and a medial locator member at a distal end;
- a bracket pivotally attached to the swiveling arm;
- and
- a locating arm removably attached to the bracket, the locating arm comprising a middle locator member.
A method of locating a femoral mechanical axis comprising:
- identifying a representative sphere traced by a trace point offset by a predetermined distance from a center of a knee, wherein a center of the representative sphere is coincident with a center of a femoral head;
- identifying at least three points on the representative sphere;
- locating the center of a circle defined by the at least three points on the representative sphere;
- identifying a line passing through the center of, and perpendicular to the plane of, the circle defined by the at least three points on the representative sphere;
- positioning the femur such that a line connecting the center of the femoral head and the trace point is coincident with the line passing through the center of, and perpendicular to the plane of, the circle defined by the at least three points on the representative sphere;
- and
- placing a plurality of locating devices on the femur to identify the location of the femoral mechanical axis in both the coronal and sagittal planes, such locating devices being positioned on the femur in such a way as to compensate for the predetermined offset of the trace point from the center of the knee so that the line connecting the center of the femoral head and the trace point has a predetermined angular offset from the femoral mechanical axis.
Dependencies are inferred from the claim text.