In order, in an intervertebral implant having a core made of a swellable material and having a vertebral-body locating face on its top and/or bottom side, which is connected to the swellable core, to reduce the shearing forces between the swellable core and the vertebral-body locating face during swelling...http://www.google.se/patents/US8021424?utm_source=gb-gplus-sharePatent US8021424 - Intervertebral implant
