An artificial intervertebral disc including housing members including spaced inner surfaces facing each other and oppositely facing outer surfaces for engaging spaced apart intervertebral surfaces; self-adjusting bearing mechanisms operatively disposed between the inner surfaces for moving relative to the housing members to adjust and compensate for vertebral disc motion; and positioning ring for controlling motion and position of the bearing mechanisms and for absorption of compressive loads. An artificial intervertebral disc including housing members having an oval recess on the inner surfaces; oval bearing mechanisms operatively disposed within the oval recess between the inner surfaces for moving relative to the housing members to adjust and compensate for vertebral disc motion; and oval positioning ring. A spring member for an artificial intervertebral disc including a substantially annular body having an axially extended bore therethrough defining a passageway.