The invention is an expandable box-shaped spinal implant used to fuse adjacent vertebra in the patient's spine. The implant includes three interlocking parts, which are the superior section, the inferior section, and the U-shaped expander cap. The Box-shaped expandable spinal implant is formed by mating...http://www.google.es/patents/US5980522?utm_source=gb-gplus-sharePatente US5980522 - Expandable spinal implants
