Leg Length Discrepancy Following Hip Replacement Surgery
Overview
While many people have slight differences in the length of one leg compared to the other, a significant difference between the two legs can cause problems. Leg length discrepancies can disturb the way a person walks, how his or her spine lines up and strain hip joints.
Causes
Leg discrepancy can develop from a medical issue in any portion of the femur or tibia. One leg may lengthen, but leg shortening is much more common. Factors that can cause leg length discrepancy include inherited growth deficiencies. Infections. A bone infection can cause delayed growth in the affected limb. Injury. If your child breaks a leg, it may be shorter once it heals. This is most likely to happen if the fracture or break was complicated, an open fracture, or an injury that affected the growth plate near the end of the bone. Alternatively, a break can cause bones to grow faster after healing, making a leg longer. Tumors. Legg-Calve-Perthes disease. This is a condition that affects the ball (femoral head) of the hip joint. The femoral head may be friable and damage easily, sometimes leading to shortening of the thigh bone. Hemihypertrophy. In children with this condition, one side of the body grows more quickly than the other. Vascular malformations. These are abnormal clusters of veins and arteries that can form close to the bone and stimulate growth. Juvenile arthritis. Inflammation from arthritis can stimulate growth in the affected leg and cause discrepancy.
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
There are several orthopedic tests that are used, but they are rudimentary and have some degree of error. Even using a tape measure with specific anatomic landmarks has its errors. Most leg length differences can be seen with a well trained eye, but I always recommend what is called a scanagram, or a x-ray bone length study (see picture above). This test will give a precise measurement in millimeters of the length difference.
Non Surgical Treatment
You may be prescribed a heel lift, which will equal out your leg length and decrease stress on your low back and legs. If it?s your pelvis causing the leg length discrepancy, then your physical therapist could use your muscles to realign your pelvis and then strengthen your core/abdominal region to minimize the risk of such malalignment happening again. If you think that one leg may be longer than the other and it is causing you to have pain or you are just curious, then make an appointment with a physical therapist.
Surgical Treatment
Surgical treatments vary in complexity. Sometimes the goal of surgery is to stop the growth of the longer limb. Other times, surgeons work to lengthen the shorter limb. Orthopedic surgeons may treat children who have limb-length conditions with one or a combination of these surgical techniques. Bone resection. An operation to remove a section of bone, evening out the limbs in teens or adults who are no longer growing. Epiphyseal stapling. An operation to slow the rate of growth of the longer limb by inserting staples into the growth plate, then removing them when the desired result is achieved. Epiphysiodesis. An operation to slow the rate of growth of the longer limb by creating a permanent bony ridge near the growth plate. Limb lengthening. A procedure (also called distraction osteogenesis or the Ilizarov procedure) that involves attaching an internal or external fixator to a limb and gradually pulling apart bone segments to grow new bone between them. There are several ways your doctor can predict the final LLD, and thus the timing of the surgery. The easiest way is the so-called Australian method, popularised by Dr. Malcolm Menelaus, an Australian orthopedic surgeon. According to this method, growth in girls is estimated to stop at age 14, and in boys at age 16 years. The femur grows at the rate of 10 mm. a year, and the upper tibia at the rate of 6 mm. a year. Using simple arithmetic, one can get a fairly good prediction of future growth. This of course, is an average, and the patient may be an average. To cut down the risk of this, the doctor usually measures leg length using special X-ray technique (called a Scanogram) on three occasions over at least one year duration to estimate growth per year. He may also do an X-ray of the left hand to estimate the bone age (which in some cases may differ from chronological age) by comparing it with an atlas of bone age. In most cases, however, the bone age and chronological age are quite close. Another method of predicting final LLD is by using Anderson and Green?s remaining growth charts. This is a very cumbersome method, but was till the 1970?s, the only method of predicting remaining growth. More recently, however, a much more convenient method of predicting LLD was discovered by Dr. Colin Moseley from Montreal. His technique of using straight line graphs to plot growth of leg lengths is now the most widely used method of predicting leg length discrepancy. Whatever method your doctor uses, over a period of one or two years, once he has a good idea of the final LLD, he can then formulate a plan to equalize leg lengths. Epiphyseodesis is usually done in the last 2 to 3 years of growth, giving a maximum correction of about 5 cm. Leg lengthening can be done at any age, and can give corrections of 5 to10 cm., or more.
While many people have slight differences in the length of one leg compared to the other, a significant difference between the two legs can cause problems. Leg length discrepancies can disturb the way a person walks, how his or her spine lines up and strain hip joints.
Causes
Leg discrepancy can develop from a medical issue in any portion of the femur or tibia. One leg may lengthen, but leg shortening is much more common. Factors that can cause leg length discrepancy include inherited growth deficiencies. Infections. A bone infection can cause delayed growth in the affected limb. Injury. If your child breaks a leg, it may be shorter once it heals. This is most likely to happen if the fracture or break was complicated, an open fracture, or an injury that affected the growth plate near the end of the bone. Alternatively, a break can cause bones to grow faster after healing, making a leg longer. Tumors. Legg-Calve-Perthes disease. This is a condition that affects the ball (femoral head) of the hip joint. The femoral head may be friable and damage easily, sometimes leading to shortening of the thigh bone. Hemihypertrophy. In children with this condition, one side of the body grows more quickly than the other. Vascular malformations. These are abnormal clusters of veins and arteries that can form close to the bone and stimulate growth. Juvenile arthritis. Inflammation from arthritis can stimulate growth in the affected leg and cause discrepancy.
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
There are several orthopedic tests that are used, but they are rudimentary and have some degree of error. Even using a tape measure with specific anatomic landmarks has its errors. Most leg length differences can be seen with a well trained eye, but I always recommend what is called a scanagram, or a x-ray bone length study (see picture above). This test will give a precise measurement in millimeters of the length difference.
Non Surgical Treatment
You may be prescribed a heel lift, which will equal out your leg length and decrease stress on your low back and legs. If it?s your pelvis causing the leg length discrepancy, then your physical therapist could use your muscles to realign your pelvis and then strengthen your core/abdominal region to minimize the risk of such malalignment happening again. If you think that one leg may be longer than the other and it is causing you to have pain or you are just curious, then make an appointment with a physical therapist.
Surgical Treatment
Surgical treatments vary in complexity. Sometimes the goal of surgery is to stop the growth of the longer limb. Other times, surgeons work to lengthen the shorter limb. Orthopedic surgeons may treat children who have limb-length conditions with one or a combination of these surgical techniques. Bone resection. An operation to remove a section of bone, evening out the limbs in teens or adults who are no longer growing. Epiphyseal stapling. An operation to slow the rate of growth of the longer limb by inserting staples into the growth plate, then removing them when the desired result is achieved. Epiphysiodesis. An operation to slow the rate of growth of the longer limb by creating a permanent bony ridge near the growth plate. Limb lengthening. A procedure (also called distraction osteogenesis or the Ilizarov procedure) that involves attaching an internal or external fixator to a limb and gradually pulling apart bone segments to grow new bone between them. There are several ways your doctor can predict the final LLD, and thus the timing of the surgery. The easiest way is the so-called Australian method, popularised by Dr. Malcolm Menelaus, an Australian orthopedic surgeon. According to this method, growth in girls is estimated to stop at age 14, and in boys at age 16 years. The femur grows at the rate of 10 mm. a year, and the upper tibia at the rate of 6 mm. a year. Using simple arithmetic, one can get a fairly good prediction of future growth. This of course, is an average, and the patient may be an average. To cut down the risk of this, the doctor usually measures leg length using special X-ray technique (called a Scanogram) on three occasions over at least one year duration to estimate growth per year. He may also do an X-ray of the left hand to estimate the bone age (which in some cases may differ from chronological age) by comparing it with an atlas of bone age. In most cases, however, the bone age and chronological age are quite close. Another method of predicting final LLD is by using Anderson and Green?s remaining growth charts. This is a very cumbersome method, but was till the 1970?s, the only method of predicting remaining growth. More recently, however, a much more convenient method of predicting LLD was discovered by Dr. Colin Moseley from Montreal. His technique of using straight line graphs to plot growth of leg lengths is now the most widely used method of predicting leg length discrepancy. Whatever method your doctor uses, over a period of one or two years, once he has a good idea of the final LLD, he can then formulate a plan to equalize leg lengths. Epiphyseodesis is usually done in the last 2 to 3 years of growth, giving a maximum correction of about 5 cm. Leg lengthening can be done at any age, and can give corrections of 5 to10 cm., or more.
