Overview
The two major categorizations of LLD are structural and functional. A third more minor category is environmental. In structural LLD there is an actual anatomical difference in the bones of the lower extremities where one side becomes shorter than the other. This type of LLD may be genetic, where the person is born in this way. In other cases it may be due to injury or infection through the growth phases of early childhood or adolescence. Some spinal abnormalities like scoliosis can also cause this condition. Functional LLD is where the bones are not the cause of difference but a muscle or pelvic condition has the effect of weakening the leg on one side. Conditions that can cause this are muscle inflexibility, adduction contractures and pelvic obliquity (amongst others). The third less severe category of environmental LLD is caused by discrepancies in the surface that the feet and legs are resting or walking on. Banked, uneven or curved surfaces can all cause environmental LLD. In LLD the asymmetric nature of the legs in relation to hips and back caused the centre of gravity to shift from its natural position. This then results in the body attempting to compensate by either tilting the pelvic areas towards the shorter side, increased knee flexing on the longer side, flexion of the ankle plantar and foot supination towards the shorter side.
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
Leg length discrepancy may be diagnosed during infancy or later in childhood, depending on the cause. Conditions such as hemihypertrophy or hemiatrophy are often diagnosed following standard newborn or infant examinations by a pediatrician, or anatomical asymmetries may be noticed by a child's parents. For young children with hemihypertophy as the cause of their LLD, it is important that they receive an abdominal ultrasound of the kidneys to insure that Wilm's tumor, which can lead to hypertrophy in the leg on the same side, is not present. In older children, LLD is frequently first suspected due to the emergence of a progressive limp, warranting a referral to a pediatric orthopaedic surgeon. The standard workup for LLD is a thorough physical examination, including a series of measurements of the different portions of the lower extremities with the child in various positions, such as sitting and standing. The orthopaedic surgeon will observe the child while walking and performing other simple movements or tasks, such as stepping onto a block. In addition, a number of x-rays of the legs will be taken, so as to make a definitive diagnosis and to assist with identification of the possible etiology (cause) of LLD. Orthopaedic surgeons will compare x-rays of the two legs to the child's age, so as to assess his/her skeletal age and to obtain a baseline for the possibility of excessive growth rate as a cause. A growth chart, which compares leg length to skeletal age, is a simple but essential tool used over time to track the progress of the condition, both before and after treatment. Occasionally, a CT scan or MRI is required to further investigate suspected causes or to get more sophisticated radiological pictures of bone or soft tissue.
Non Surgical Treatment
Treatment of leg length inequality involves many different approaches, such as orthotics, epiphysiodesis, shortening, and lengthening, which can be used alone or combined in an effort to achieve equalization of leg lengths. Leg length inequality of 2 cm or less is usually not a functional problem. Often, leg length can be equalized with a shoe lift, which usually corrects about two thirds of the leg length inequality. Up to 1 cm can be inserted in the shoe. For larger leg length inequalities, the shoe must be built up. This needs to be done for every shoe worn, thus limiting the type of shoe that the patient can wear. Leg length inequalities beyond 5 cm are difficult to treat with a shoe lift. The shoe looks unsightly, and often the patient complains of instability with such a large lift. A foot-in-foot prosthesis can be used for larger leg length inequalities. This is often done as a temporizing measure for young children with significant leg length inequalities. The prosthesis is bulky, and a fixed equinus contracture may result.
Surgical Treatment
Surgical lengthening of the shorter extremity (upper or lower) is another treatment option. The bone is lengthened by surgically applying an external fixator to the extremity in the operating room. 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 tension is created by the frame when it is "distracted" by the patient or family member who turns an affixed dial several times daily. The lengthening process begins approximately five to ten days after surgery. The bone may lengthen one millimeter per day, or approximately one inch per month. Lengthening may be slower in adults overall and in a bone that has been previously injured or undergone prior surgery. Bones in patients with potential blood vessel abnormalities (i.e., cigarette smokers) may also lengthen more slowly. The external fixator is worn until the bone is strong enough to support the patient safely, approximately three months per inch of lengthening. This may vary, however, due to factors such as age, health, smoking, participation in rehabilitation, etc. Risks of this procedure include infection at the site of wires and pins, stiffness of the adjacent joints and slight over or under correction of the bone?s length. Lengthening requires regular follow up visits to the physician?s office, meticulous hygiene of the pins and wires, diligent adjustment of the frame several times daily and rehabilitation as prescribed by your physician.
The two major categorizations of LLD are structural and functional. A third more minor category is environmental. In structural LLD there is an actual anatomical difference in the bones of the lower extremities where one side becomes shorter than the other. This type of LLD may be genetic, where the person is born in this way. In other cases it may be due to injury or infection through the growth phases of early childhood or adolescence. Some spinal abnormalities like scoliosis can also cause this condition. Functional LLD is where the bones are not the cause of difference but a muscle or pelvic condition has the effect of weakening the leg on one side. Conditions that can cause this are muscle inflexibility, adduction contractures and pelvic obliquity (amongst others). The third less severe category of environmental LLD is caused by discrepancies in the surface that the feet and legs are resting or walking on. Banked, uneven or curved surfaces can all cause environmental LLD. In LLD the asymmetric nature of the legs in relation to hips and back caused the centre of gravity to shift from its natural position. This then results in the body attempting to compensate by either tilting the pelvic areas towards the shorter side, increased knee flexing on the longer side, flexion of the ankle plantar and foot supination towards the shorter side.
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
Leg length discrepancy may be diagnosed during infancy or later in childhood, depending on the cause. Conditions such as hemihypertrophy or hemiatrophy are often diagnosed following standard newborn or infant examinations by a pediatrician, or anatomical asymmetries may be noticed by a child's parents. For young children with hemihypertophy as the cause of their LLD, it is important that they receive an abdominal ultrasound of the kidneys to insure that Wilm's tumor, which can lead to hypertrophy in the leg on the same side, is not present. In older children, LLD is frequently first suspected due to the emergence of a progressive limp, warranting a referral to a pediatric orthopaedic surgeon. The standard workup for LLD is a thorough physical examination, including a series of measurements of the different portions of the lower extremities with the child in various positions, such as sitting and standing. The orthopaedic surgeon will observe the child while walking and performing other simple movements or tasks, such as stepping onto a block. In addition, a number of x-rays of the legs will be taken, so as to make a definitive diagnosis and to assist with identification of the possible etiology (cause) of LLD. Orthopaedic surgeons will compare x-rays of the two legs to the child's age, so as to assess his/her skeletal age and to obtain a baseline for the possibility of excessive growth rate as a cause. A growth chart, which compares leg length to skeletal age, is a simple but essential tool used over time to track the progress of the condition, both before and after treatment. Occasionally, a CT scan or MRI is required to further investigate suspected causes or to get more sophisticated radiological pictures of bone or soft tissue.
Non Surgical Treatment
Treatment of leg length inequality involves many different approaches, such as orthotics, epiphysiodesis, shortening, and lengthening, which can be used alone or combined in an effort to achieve equalization of leg lengths. Leg length inequality of 2 cm or less is usually not a functional problem. Often, leg length can be equalized with a shoe lift, which usually corrects about two thirds of the leg length inequality. Up to 1 cm can be inserted in the shoe. For larger leg length inequalities, the shoe must be built up. This needs to be done for every shoe worn, thus limiting the type of shoe that the patient can wear. Leg length inequalities beyond 5 cm are difficult to treat with a shoe lift. The shoe looks unsightly, and often the patient complains of instability with such a large lift. A foot-in-foot prosthesis can be used for larger leg length inequalities. This is often done as a temporizing measure for young children with significant leg length inequalities. The prosthesis is bulky, and a fixed equinus contracture may result.
Surgical Treatment
Surgical lengthening of the shorter extremity (upper or lower) is another treatment option. The bone is lengthened by surgically applying an external fixator to the extremity in the operating room. 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 tension is created by the frame when it is "distracted" by the patient or family member who turns an affixed dial several times daily. The lengthening process begins approximately five to ten days after surgery. The bone may lengthen one millimeter per day, or approximately one inch per month. Lengthening may be slower in adults overall and in a bone that has been previously injured or undergone prior surgery. Bones in patients with potential blood vessel abnormalities (i.e., cigarette smokers) may also lengthen more slowly. The external fixator is worn until the bone is strong enough to support the patient safely, approximately three months per inch of lengthening. This may vary, however, due to factors such as age, health, smoking, participation in rehabilitation, etc. Risks of this procedure include infection at the site of wires and pins, stiffness of the adjacent joints and slight over or under correction of the bone?s length. Lengthening requires regular follow up visits to the physician?s office, meticulous hygiene of the pins and wires, diligent adjustment of the frame several times daily and rehabilitation as prescribed by your physician.
