Overview
There are generally two kinds of leg length discrepancies. Structural discrepancy occurs when either the thigh (femur) or shin (tibia) bone in one leg is actually shorter than the corresponding bone in the other leg. Functional discrepancy occurs when the leg lengths are equal, but symmetry is altered somewhere above the leg, which in turn disrupts the symmetry of the legs. For example, developmental dislocation of the hip (DDH) can cause a functional discrepancy. In DDH, the top of the leg bone (femur) that is not properly positioned in the hip socket may hang lower than the femur on the other side, giving the appearance and symptoms of a leg length discrepancy.
Causes
LLDs are very common. Sometimes the cause isn?t known. But the known causes of LLD in children include, injury or infection that slows growth of one leg bone. Injury to the growth plate (a soft part of a long bone that allows the bone to grow). Growth plate injury can slow bone growth in that leg. Fracture to a leg bone that causes overgrowth of the bone as it heals. A congenital (present at birth) problem (one whole side of the child?s body may be larger than the other side). Conditions that affect muscles and nerves, such as polio.
Symptoms
The effects vary from patient to patient, depending on the cause of the discrepancy and the magnitude of the difference. Differences of 3 1/2 to 4 percent of the total length of the lower extremity (4 cm or 1 2/3 inches in an average adult), including the thigh, lower leg and foot, may cause noticeable abnormalities while walking and require more effort to walk. Differences between the lengths of the upper extremities cause few problems unless the difference is so great that it becomes difficult to hold objects or perform chores with both hands. You and your physician can decide what is right for you after discussing the causes, treatment options and risks and benefits of limb lengthening, including no treatment at all. Although an LLD may be detected on a screening examination for curvature of the spine (scoliosis), LLD does not cause scoliosis. There is controversy about the effect of LLD on the spine. Some studies indicate that people with an LLD have a greater incidence of low back pain and an increased susceptibility to injuries, but other studies refute this relationship.
Diagnosis
A doctor will generally take a detailed medical history of both the patient and family, including asking about recent injuries or illnesses. He or she will carefully examine the patient, observing how he or she moves and stands. If necessary, an orthopedic surgeon will order X-ray, bone age determinations and computed tomography (CT) scans or magnetic resonance imaging (MRI).
Non Surgical Treatment
Treatment is based on an estimate of how great the difference in leg length will be when the child grows up, Small differences (a half inch or less) do not need treatment. Differences of a half to one inch may require a lift inside the shoe.
Surgical Treatment
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.
There are generally two kinds of leg length discrepancies. Structural discrepancy occurs when either the thigh (femur) or shin (tibia) bone in one leg is actually shorter than the corresponding bone in the other leg. Functional discrepancy occurs when the leg lengths are equal, but symmetry is altered somewhere above the leg, which in turn disrupts the symmetry of the legs. For example, developmental dislocation of the hip (DDH) can cause a functional discrepancy. In DDH, the top of the leg bone (femur) that is not properly positioned in the hip socket may hang lower than the femur on the other side, giving the appearance and symptoms of a leg length discrepancy.
Causes
LLDs are very common. Sometimes the cause isn?t known. But the known causes of LLD in children include, injury or infection that slows growth of one leg bone. Injury to the growth plate (a soft part of a long bone that allows the bone to grow). Growth plate injury can slow bone growth in that leg. Fracture to a leg bone that causes overgrowth of the bone as it heals. A congenital (present at birth) problem (one whole side of the child?s body may be larger than the other side). Conditions that affect muscles and nerves, such as polio.
Symptoms
The effects vary from patient to patient, depending on the cause of the discrepancy and the magnitude of the difference. Differences of 3 1/2 to 4 percent of the total length of the lower extremity (4 cm or 1 2/3 inches in an average adult), including the thigh, lower leg and foot, may cause noticeable abnormalities while walking and require more effort to walk. Differences between the lengths of the upper extremities cause few problems unless the difference is so great that it becomes difficult to hold objects or perform chores with both hands. You and your physician can decide what is right for you after discussing the causes, treatment options and risks and benefits of limb lengthening, including no treatment at all. Although an LLD may be detected on a screening examination for curvature of the spine (scoliosis), LLD does not cause scoliosis. There is controversy about the effect of LLD on the spine. Some studies indicate that people with an LLD have a greater incidence of low back pain and an increased susceptibility to injuries, but other studies refute this relationship.
Diagnosis
A doctor will generally take a detailed medical history of both the patient and family, including asking about recent injuries or illnesses. He or she will carefully examine the patient, observing how he or she moves and stands. If necessary, an orthopedic surgeon will order X-ray, bone age determinations and computed tomography (CT) scans or magnetic resonance imaging (MRI).
Non Surgical Treatment
Treatment is based on an estimate of how great the difference in leg length will be when the child grows up, Small differences (a half inch or less) do not need treatment. Differences of a half to one inch may require a lift inside the shoe.
Surgical Treatment
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.