Having one leg longer than the other is relatively common. The condition is known as leg length discrepancy.
Some research indicates that 40–70% of people have some form of leg length discrepancy (LLD).
The differences in leg length can range from a fraction of an inch to several inches. The greater the difference, the more likely it is that the person will experience issues with gait, posture, and pain.
In this article, we discuss the causes and symptoms of LLD. We also provide information on the diagnosis of LLD and the treatment options available.
There are two types of LLD: functional and structural. These types have different causes.
In functional LLD, the leg bones are equal in length. However, one leg appears longer than the other due to an issue with one of the following body parts:
In children, functional LLD can occur when a child is born with an issue that alters their hip alignment.
In adults, functional LLD can result from chronic pain or arthritis and associated problems in the spine, hip, or knee.
Neuromuscular conditions are another potential cause of functional LLD, as these conditions can affect a person’s alignment and posture.
In some cases, exercise can contribute to functional LLD. If an athlete trains in a way that causes muscle imbalances or weaknesses, they may temporarily experience functional LLD.
Structural LLD occurs when either the thigh bone (femur) or the shin bone (tibia) is shorter in one leg than in the other. The condition typically presents at birth, but it can also happen as a child grows.
Some potential causes of structural LLD include:
- Bone injuries: Bone breaks can slow down bone growth in one leg. This effect is especially likely if the break caused the bone to shatter into many pieces or injured the surrounding muscle tissue. Occasionally, a fracture that is healing may trigger an overgrowth of bone tissue. This overgrowth is most common in young children who have femur fractures.
- Growth plate injuries: Growth plates are areas of cartilage that sit near the end of the long bones. Sometimes, a growth plate can sustain an injury, which may cause the bone to grow faster or slower than the bone on the opposite side of the body.
- Bone diseases: Bone diseases such as osteomyelitis can cause damage to the bone’s growth plate. This damage eventually leads to LLD.
- Bone tumors: Bone tumors and their treatments can affect bone growth and contribute to LLD.
- Juvenile arthritis (JA): JA is a childhood autoimmune disease that causes inflammation of the tissue inside the joints. It can cause discrepancies in bone growth.
The main symptom of LLD is having one leg longer than the other. If the discrepancy is very small, there may not be any other symptoms.
However, a 2017 study notes that a discrepancy as small as 2 centimeters (cm) can cause the pelvis to compensate for imbalances in posture.
Moderate-to-severe cases of LLD can cause additional symptoms, including:
- gait issues, such as a limp
- pain in the back, hip, knee, or ankle
- increased tiredness
The study authors also note that LLD can affect a person’s overall quality of life.
People who suspect that they have one leg longer than the other should see a doctor for a diagnosis.
While waiting for an appointment, a person could try the following home test to see whether there is a possibility of LLD.
To perform a home test, the person should:
- Remove their shoes and socks.
- Lie down on the floor, keeping the legs together.
- Ask a friend or family member to place the palms of their hands on the person’s hip bones, so that they have one hand on each hip.
- Ask the helper to move the person’s hips gently from side to side for approximately 60 seconds. This motion helps loosen up tight muscles.
- Ask the helper to check the alignment of the person’s ankle bones.
Ankles that are not aligned could indicate LLD. It will be necessary to see a doctor to confirm LLD and to determine whether it is a functional or structural issue.
A doctor may use several methods to diagnose LLD. These include:
The type of LLD will determine the treatment that a person receives.
Treating functional LLD
The treatment for functional LLD typically involves physical therapy, massage, and specific exercises to correct areas of imbalance and weakness. It is also important to correct poor posture.
The exact type and number of interventions that a person needs will depend on the underlying cause and severity of the LLD.
Exercising and functional LLD
Exercises may help correct some functional LLDs. However, it is important that people use the correct stretching and strengthening techniques. They should also take care to exercise the side of the body that will help correct the LLD.
To avoid causing further issues, it may be sensible to seek the help of a physical therapist. The therapist can identify areas of imbalance and recommend appropriate exercises.
Treating structural LLD
Correcting structural LLD is less straightforward. Treatment typically depends on the difference in length between the legs.
Some potential treatment options include:
A shoe lift
A person who has mild LLD of less than 1 inch may benefit from wearing a shoe lift inside the shoe on the shorter leg. A shoe lift can alleviate back pain and improve a person’s gait.
Surgery may be necessary to treat more significant LLDs. Several surgical options are available, each of which aims to do one of the following:
- shorten the longer leg
- lengthen the shorter leg
- inhibit the growth of the longer leg
Following surgery, people will require regular follow-up visits to the doctor’s office. They will also need extensive rehabilitation that includes exercise and physical therapy.
Having one leg longer than the other is a relatively common occurrence. A leg length discrepancy may be functional or structural in nature.
Minor discrepancies often cause no symptoms or problems. However, moderate-to-severe asymmetry may cause issues with walking and posture, and it can contribute to hip and back pain.
People should see a doctor if they suspect that they or their child has LLD. A doctor can diagnose the condition and recommend appropriate treatments.