A replacement device for resurfacing a joint surface of a femur and a
method of making and installing such a device is provided. The custom
replacement device is designed to substantially fit the trochlear groove
surface, of an individual femur. Thereby creating a "customized"
replacement device for that individual femur and maintaining the original
kinematics of the joint. The replacement device may be defined by four
boundary points, and a first and a second surface. The first of four
points is 3 to 5 mm from the point of attachment of the anterior cruciate
ligament to the femur. The second point is near the bottom edge of the
end of the natural articulatar cartilage. The third point is at the top
ridge of the right condyle and the fourth point at the top ridge of the
left condyle of the femur. The top surface is designed so as to maintain
centrally directed tracking of the patella perpendicular to the plane
established by the distal end of the femoral condyles and aligned with
the center of the femoral head.