Improved methods and apparatuses for vertebral body distraction and fusion in accordance with various embodiments employ mechanisms for stabilizing a device so that the device can stay in the body and stably support the disc space during vertebral fusion following distraction of the adjacent vertebra by operation of the device. The device is inserted into the disc space and distracted from a compressed configuration to an expanded configuration to distract the disc space. Mechanisms for stabilizing the device in the expanded configuration constrain the device to zero degrees of freedom of movement to allow the device to stably support the disc space. A bone growth stimulant for promoting vertebral fusion can be inserted into an open space defined by the device, which continues to stably support the disc space during vertebral fusion.
