US Patent 9393128 Expandable vertebral prosthesis

The present invention relates to an expandable prosthetic implant device for engagement between vertebrae generally comprising an inner member, outer member, and a gear member. The gear member may be axially fixed to the outer member and freely rotatable with respect to the outer member and the gear member may threadedly engage a threaded portion of the inner member to translate the inner member. The implant is configured to engage the vertebrae in a predetermined alignment and the gear member includes gear teeth exposed to the exterior and configured to be accessible by a tool member at a plurality of angular positions around the perimeter of the implant device.