An intramedullar distraction device for bone elongation that is completely mechanical in operation, wherein a novel rotating button system allows inverting the device ratchet movement, thereby enabling the reduction of the length of the device, if needed, in order to offer the surgeon operating flexibility before finally anchoring the device on the bone. Furthermore, a locking system allows for locking the ratchet once the desired elongation has been reached, thus avoiding potential mistaken elongations. In addition, a unique alignment hole provides a simple, precise tool to easily and correctly align the device within the bone. The present device operates without the assistance of external mechanisms, motors, or tools, and once inserted, the user can actuate the device without assistance. This device is available in a wide variety of diameters and lengths, and is useful in all long bones.