Overview
The bone is lengthened by surgically applying an external fixation device to the leg. The external fixator, a scaffold-like frame, is connected to the bone with wires, pins, or both. A small crack is made in the bone and the frame creates tension when the patient or family member turns its dial. This is done several times each day. The lengthening process begins approximately five to 10 days after surgery. The bone may lengthen 1 millimeter per day, or approximately 1 inch per month. Lengthening may be slower in a bone that was previously injured. It may also be slower if the leg was operated on before. Bones in patients with potential blood vessel abnormalities, such as cigarette smokers, may also need to be lengthened more slowly. The external fixator is worn until the bone is strong enough to support the patient safely. This usually takes about three months for each inch. Factors such as age, health, smoking and participation in rehabilitation can affect the amount of time needed.
Causes
A number of causes may lead to leg length discrepancy in children. Differences in leg length frequently follow fractures in the lower extremities in children due to over or under stimulation of the growth plates in the broken leg. Leg length discrepancy may also be caused by a congenital abnormality associated with a condition called hemihypertrophy. Or it may result from neuromuscular diseases such as polio and cerebral palsy. Many times, no cause can be identified. A small leg length discrepancy of a quarter of an inch or less is quite common in the general population and of no clinical significance. Larger leg length discrepancies become more significant. The long-term consequences of a short leg may include knee pain, back pain, and abnormal gait or limp.
Symptoms
The effects of limb length discrepancy vary from patient to patient, depending on the cause and size of the difference. Differences of 3 1/2 percent to 4 percent of the total length of the leg (about 4 cm or 1 2/3 inches in an average adult) may cause noticeable abnormalities when walking. These differences may require the patient to exert more effort to walk. There is controversy about the effect of limb length discrepancy on back pain. Some studies show that people with a limb length discrepancy have a greater incidence of low back pain and an increased susceptibility to injuries. Other studies do not support this finding.
Diagnosis
Asymmetry is a clue that a LLD is present. The center of gravity will shift to the short limb side and patients will try to compensate, displaying indications such as pelvic tilt, lumbar scoliosis, knee flexion, or unilateral foot pronation. Asking simple questions such as, "Do you favor one leg over the other?" or, "Do you find it uncomfortable to stand?" may also provide some valuable information. Performing a gait analysis will yield some clues as to how the patient compensates during ambulation. Using plantar pressure plates can indicate load pressure differences between the feet. It is helpful if the gait analysis can be video-recorded and played back in slow motion to catch the subtle aspects of movement.
Non Surgical Treatment
Internal heel lifts: Putting a simple heel lift inside the shoe or onto a foot orthotic has the advantage of being transferable to many pairs of shoes. It is also aesthetically more pleasing as the lift remains hidden from view. However, there is a limit as to how high the lift can be before affecting shoe fit. Dress shoes will usually only accommodate small lifts (1/8"1/4") before the heel starts to piston out of the shoe. Sneakers and workboots may allow higher lifts, e.g., up to 1/2", before heel slippage problems arise. External heel lifts: If a lift of greater than 1/2" is required, you should consider adding to the outsole of the shoe. In this way, the shoe fit remains good. Although some patients may worry about the cosmetics of the shoe, it does ensure better overall function. Nowadays with the development of synthetic foams and crepes, such lifts do not have to be as heavy as the cork buildups of the past. External buildups are not transferable and they will wear down over time, so the patient will need to be vigilant in having them repaired. On ladies' high-heel shoes, it may be possible to lower one heel and thereby correct the imbalance.
Surgical Treatment
Surgeries to lengthen a leg are generally only performed when there is a difference in leg length of greater than four centimeters. These types of surgeries can be more difficult and have more complications, such as infections, delayed healing, dislocations, and high blood pressure. In a several step process, bone lengthening surgeries involve cutting a bone in two in order to allow new bone growth to occur. After the bone is cut, a special apparatus is worn with pins that will pull the bone apart at approximately one millimeter per day. This causes osteogenesis, or new bone growth, in between the cut bone segments. A cast or brace may be required for several months after surgery to allow the new bone growth to harden and provide extra support.
The bone is lengthened by surgically applying an external fixation device to the leg. The external fixator, a scaffold-like frame, is connected to the bone with wires, pins, or both. A small crack is made in the bone and the frame creates tension when the patient or family member turns its dial. This is done several times each day. The lengthening process begins approximately five to 10 days after surgery. The bone may lengthen 1 millimeter per day, or approximately 1 inch per month. Lengthening may be slower in a bone that was previously injured. It may also be slower if the leg was operated on before. Bones in patients with potential blood vessel abnormalities, such as cigarette smokers, may also need to be lengthened more slowly. The external fixator is worn until the bone is strong enough to support the patient safely. This usually takes about three months for each inch. Factors such as age, health, smoking and participation in rehabilitation can affect the amount of time needed.
Causes
A number of causes may lead to leg length discrepancy in children. Differences in leg length frequently follow fractures in the lower extremities in children due to over or under stimulation of the growth plates in the broken leg. Leg length discrepancy may also be caused by a congenital abnormality associated with a condition called hemihypertrophy. Or it may result from neuromuscular diseases such as polio and cerebral palsy. Many times, no cause can be identified. A small leg length discrepancy of a quarter of an inch or less is quite common in the general population and of no clinical significance. Larger leg length discrepancies become more significant. The long-term consequences of a short leg may include knee pain, back pain, and abnormal gait or limp.
Symptoms
The effects of limb length discrepancy vary from patient to patient, depending on the cause and size of the difference. Differences of 3 1/2 percent to 4 percent of the total length of the leg (about 4 cm or 1 2/3 inches in an average adult) may cause noticeable abnormalities when walking. These differences may require the patient to exert more effort to walk. There is controversy about the effect of limb length discrepancy on back pain. Some studies show that people with a limb length discrepancy have a greater incidence of low back pain and an increased susceptibility to injuries. Other studies do not support this finding.
Diagnosis
Asymmetry is a clue that a LLD is present. The center of gravity will shift to the short limb side and patients will try to compensate, displaying indications such as pelvic tilt, lumbar scoliosis, knee flexion, or unilateral foot pronation. Asking simple questions such as, "Do you favor one leg over the other?" or, "Do you find it uncomfortable to stand?" may also provide some valuable information. Performing a gait analysis will yield some clues as to how the patient compensates during ambulation. Using plantar pressure plates can indicate load pressure differences between the feet. It is helpful if the gait analysis can be video-recorded and played back in slow motion to catch the subtle aspects of movement.
Non Surgical Treatment
Internal heel lifts: Putting a simple heel lift inside the shoe or onto a foot orthotic has the advantage of being transferable to many pairs of shoes. It is also aesthetically more pleasing as the lift remains hidden from view. However, there is a limit as to how high the lift can be before affecting shoe fit. Dress shoes will usually only accommodate small lifts (1/8"1/4") before the heel starts to piston out of the shoe. Sneakers and workboots may allow higher lifts, e.g., up to 1/2", before heel slippage problems arise. External heel lifts: If a lift of greater than 1/2" is required, you should consider adding to the outsole of the shoe. In this way, the shoe fit remains good. Although some patients may worry about the cosmetics of the shoe, it does ensure better overall function. Nowadays with the development of synthetic foams and crepes, such lifts do not have to be as heavy as the cork buildups of the past. External buildups are not transferable and they will wear down over time, so the patient will need to be vigilant in having them repaired. On ladies' high-heel shoes, it may be possible to lower one heel and thereby correct the imbalance.
Surgical Treatment
Surgeries to lengthen a leg are generally only performed when there is a difference in leg length of greater than four centimeters. These types of surgeries can be more difficult and have more complications, such as infections, delayed healing, dislocations, and high blood pressure. In a several step process, bone lengthening surgeries involve cutting a bone in two in order to allow new bone growth to occur. After the bone is cut, a special apparatus is worn with pins that will pull the bone apart at approximately one millimeter per day. This causes osteogenesis, or new bone growth, in between the cut bone segments. A cast or brace may be required for several months after surgery to allow the new bone growth to harden and provide extra support.