an expansion assembly expands a vertebral implant . the vertebral implant has an inner cylindrical assembly adapted for insertion into an outer cylindrical assembly having an outer wall . the vertebral implant is expandable along an implant axis defined by the outer and inner cylindrical assemblies . the expansion assembly comprises an axle having proximal and distal end portions and an axle axis defined between the proximal and distal end portions . the expansion assembly further comprises a gear arranged about the axle axis at the proximal end portion of the axle and adapted to rotate about the axle axis to cause the inner cylindrical assembly to expand the vertebral implant . the engagement assembly also comprising a first engaging portion adapted to engage the inner cylindrical assembly and a second engaging portion adapted to engage the gear externally of the outer wall of the outer cylindrical assembly .