Leg lengthening operations increase the length of bones. These surgeries are required in cases where there is significant difference in length between the two limbs and in cases in which the patient is abnormally short and wants to increase his height.
The process of lengthening is based on slowly generating new bone and new surrounding tissues e.g. skin and muscles. During surgery a small wound is made over the bone that requires lengthening. Through this wound, the bone is divided (cut) to make an artificial fracture. After a week, the two edges of the fracture are distracted (pulled apart) gradually by a distance of 1 mm every day. This is called the distraction or lengthening phase. This distraction leads to the formation of new bone tissues between the two edges of the fracture. Also, new muscles, nerves, blood vessels and skin form due to the distraction.
Trying to lengthen the bone more rapidly is counterproductive as no enough bone will form and the nerves, vessels and muscles may become excessively stretched, thus affecting their functions.
There are different types of devices used to lengthen the bones. These may be classified into external and internal devices.
External devices (external fixators) are the most commonly used and successful devices (e.g. Ilizarov fixator). They are a group of pins and wires that are fixed to the bone and attached to a metallic frame outside the body. The bone is lengthened by lengthening this frame.
Recently, internal devices are being tried. These are fully implantable nails that are inserted inside the bone. The nail itself has a mechanism to increase its length until it reaches the required length. Thus, there is no need for an external fixator.
After the required length is achieved, distraction is stopped and the patient waits for few months for the new bone to harden (consolidation phase). After that the lengthening device is removed and the patient can walk on his limb again safely.