A spinal fixation apparatus comprising an upper and lower endplate. Depending distally in a longitudinal direction from the upper endplate is an inner sleeve that fits inside an outer sleeve that depends distally in a longitudinal direction from the lower endplate. The inner sleeve includes grooves located on its outer surface. A finger cage including resilient fingers fits around the outer sleeve. The fingers have ends that include male grooves. The ends of the fingers fit into apertures located in the outer sleeve. The apparatus further includes a locking mechanism that pushes the tips of the fingers through the apertures of the outer sleeve such that they mesh with the grooves of the inner sleeve. When the locking mechanism is unlocked the tips of the fingers disengage from the grooves of the inner sleeve, and the inner sleeve slide axially within the outer cage, adjusting the height of the device.