US Patent 8236058 Spine surgery method and implant

An implant has a first contact surface to contact a first vertebral body endplate and a second contact surface to contact a second vertebral body endplate adjacent the first vertebral body. The implant is deployable, when positioned within an intradiscal space between the first and second vertebral bodies, from a first non-expanded condition where the first contact surface has a first effective footprint area A1 to a second expanded condition where the first contact surface has a second effective footprint area A2. The ratio A2/A1 is at least 1.05.