A prosthetic spinal implant having a securing member for fixing the implant relative to an adjacent bone. In one form, the securing member is deployable into a portion of the vertebral space for affixing the implant between the vertebrae. The securing member may be disposed substantially within the body of a bearing member of the implant when the securing member is in an undeployed orientation. In other forms, the securing member is provided separately from the implant such that it may be inserted into the intervertebral space after the implant has been placed in an implanted orientation between the vertebrae. In such forms, the securing member is configured for ease of insertion between an outer bearing surface of the implant and an adjacent bone via linear or rotary motion.