An expandable implant device (100) for insertion between two vertebrae (400) is disclosed. The device (100) has an upper body (20), a lower body (40) and an external retainer band (60). The external retainer band (60) holds the upper body (20) and lower body (40) and has an inner surface having a plurality or set of upper ratchet teeth (80U) sloped for allowing upward movement and a plurality or set of lower ratchet teeth (80L) for allowing downward movement. The ratchet teeth (80) of the upper body (20) are mated or fitted to the upper teeth (80) of the retainer band (60) and the ratchet teeth (82) of the lower body (40) are mated or fitted to the lower ratchet teeth (82) of the retainer band (60). The height of the device (100) is increased by upward movement of the upper body (20) and downward movement of the lower body (40).
