Limb Deficiencies & Length Inequalities
Limb deficiency or length inequality is a condition that may occur in children and adults where the length of one limb differ from the other and this limb length differences may be seen in arms or legs. In individuals having greater differences treatment or corrective surgery may be recommended. Limb deficiencies may be caused by previous injury to the bone in the arm/leg, infection of the bone, bone diseases such as neurofibromatosis and multiple hereditary exostoses, and other conditions including arthritis.
Surgeons may not recommend surgical repair if the difference is less than one inch rather they may suggest wearing shoe lifts and shoe lifts improve walking, running and performing other activities. However if limb difference is more than an inch, surgery may be recommended.
Limb lengthening is a reconstructive procedure where the deformed bone is straightened or missing bone is replaced. It is performed in children and adults who have variations in their leg length as a result of diseases, injuries or birth defects. Limb lengthening procedure can be performed by minimally invasive procedure and may require a hospitalization of 1-2 nights.
The process of increasing the bone length depends on tissue and bone regeneration. When the bone is pulled apart, it tends to regenerate at the rate of approximately 1 mm per day. There are two phases of lengthening until the bone is healed: distraction phase and consolidation phase.
The distraction phase involves lengthening of the bone. Consolidation phase involves hardening and calcification of this new bone which is still weak due to lack of calcium.
Limb Lengthening Devices
There are two types of devices available such as external fixators and internal fixators. The external devices are attached to the bone with wires or threaded pins. The internal devices are placed inside the body, on the bone or inside the bone marrow.
Limb Lengthening Process
During surgery, a small incision is made to gain access to the part of the bone to be cut. A hospital stay of 1-3 days may be required after which rehabilitation and application of splints will be done.
The procedure involves:
- Distraction Phase
Bone lengthening begins after few days or weeks after the surgery. With the use of external fixators the patient or anyone in the family performs small twists or by applying pressure on the leg. When the bones are pulled apart new bone gradually starts to grow between the bone ends. The rate of growth is usually 1mm per day. X-rays are obtained every 2 to 3 weeks to check for new bone growth, nerve and muscle function, and also to avoid any further complications.
- Consolidation Phase
After achieving the required length, all adjustments made to the device is stopped. The newly formed bone is weak and will tend to break without the support of external or internal devices. Lengthening over nails (LON) is used as an external device. This device remains in the bone until distraction phase. After removal of LON, an internal rod is placed at the end of the bone for support. The rod hardens the newly formed bone. The function of internal device automatically stops after reaching a desired length. Bone healing is evaluated with x-rays that are obtained once in a month. The X-ray shows the amount of calcium present in the bone. After the bone is healed rods are removed.;
- Removal of the External Fixator
The removal of the external fixator device is done under general anaesthesia or when the patient is awake. After removal, a cast made of plaster of Paris (POP) is placed for a month for protection. No such cast is placed for patients with internal fixator device as the support placed internally protects the bone.