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Fixed bearing implants
Fixed bearing implants have alloy plates (either chromium cobalt or titanium) with a fixed polyethylene bearing surface and an alloy cap.
Medial pivot implants
Medial pivot implants have the same range of motion as a natural knee: rotation, bending, twisting and flexing. These implants are designed to keep the centerline of the joint in place when the knee twists, so the motion feels more like that of a natural knee.
Rotating mobile implants
Rotating mobile implants' polyethylene bearing surfaces rotate around a cone and slide back and forth. This type of implant has a larger contact surface to absorb weight and impact to reduce wear and minimize the possibility of loosening.
Posterior cruciate ligament retaining or substituting implants
The posterior cruciate ligament, or PCL, is one of the main knee ligaments. It is either kept or removed during knee replacement surgery, depending on the condition of the ligament and the type of implant being used. In PCL-retaining implants, the ligament resists rearward movement on the shinbone. In PCL-substituting implants, a raised surface on the new joint gives the knee stability to compensate for the missing PCL.
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