An expandable interbody fusion device includes superior and inferior endplates that are configured to receive a sequentially inserted stack of interlocking expansion members or wafers. The like-configured wafers include features on their top and bottom surfaces that interlock the wafers in multiple degrees...http://www.google.es/patents/US7967867?utm_source=gb-gplus-sharePatente US7967867 - Expandable interbody fusion device
