A prosthetic disc for insertion between adjacent vertebrae includes upper and lower plates, a core disposed between the plates, and at least one projection extending from at least one of the upper and lower curved surfaces of the core into at least one recess of one of the inner surfaces of the plates....http://www.google.es/patents/US8092538?utm_source=gb-gplus-sharePatente US8092538 - Intervertebral prosthetic disc
