The present invention relates to an expandable prosthetic implant device
for engagement between vertebrae generally comprising an inner member,
outer member, and gear member positioned coaxial with respect to each
other such that the inner and outer members are moveable relative to each
other along an axis. The gear member is axially fixed to the outer member
and freely rotatable with respect to the outer member and the gear member
threadedly engages a threaded portion of the inner member to translate
inner member along the axis. 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.