An expandable mechanical distension device for hollow organ growth comprising a spring stent structure to elongate hollow organs by mechanical expansion. The device preferably expands radially to engage the internal walls of the hollow organ segment at a desired treatment location and expands axially to enlarge the hollow organ segment. The distension device may be configured for the treatment of patients with insufficient hollow viscus, e.g. hollow organ deficiency such as short gut syndrome, to enhance their gut length by mechanical force.