The upper and lower surfaces 5 and 7 of an intervertebral spacer 1 inserted between the vertebrae of a spine are formed in the shape of a curved surfaces 21A and 21B each having a top portion at the middle portion in the back and forth direction. The above-mentioned upper and lower surfaces 5 and 7 are...http://www.google.de/patents/US7331996?utm_source=gb-gplus-sharePatent US7331996 - Intervertebral spacer
