A spinal cage device for fusion of spinal vertebrae comprising a cage body having a cavity defined by upper, lower, and side walls； a piston selectively insertable into the cavity through a side wall, the piston having at least one angled surface； at least one channel extending through at least one of the upper wall and the lower wall； at least one fastening member moveable within the at least one channel between a first disengaged position and a second engaged position； and wherein in second engaged position the at least one fastening member is held substantially stationary relative to the cage body by contact with the piston. According to one aspect of the invention, the device includes a locking means for supplementing fixation of the piston to the cage body.
