A spring member for an artificial intervertebral disc includes a substantially annular body including an axially extended bore therethrough defining a passageway. A seat extends radially inward towards the bore for seating therein a bearing member for adjusting and compensating vertebral disc motion....http://www.google.de/patents/US7832409?utm_source=gb-gplus-sharePatent US7832409 - Method of inserting an artificial intervertebral disc
