Leg Length Discrepancy
About a third of the population has a 1cm (½ inch) or less discrepancy between their right and left legs.
If you have a slight discrepancy in the length of your legs, you are not alone. While it may seem like a rare condition or even something that could interfere with your quality of life, that is simply not the case. Leg length discrepancies are extremely common, caused by a number of factors, and often are not noticeable and require no treatment.
Leg length discrepancies that impact your mobility will require treatment. In milder cases, an orthotic will do the trick however in more severe cases extensive shoe modifications or even surgery could be needed.
What is limb-length discrepancy?
In short, a limb-length discrepancy occurs when there is a difference in the length of your right and left leg.
Nearly 1 in 3 people have a slight discrepancy in the length of their legs and often experience no symptoms.
There are instances where leg length discrepancies are more pronounced, and this can have an impact, especially in children. Some children may have a noticeable limp or trouble participating in activities such as running or jumping.
Causes of limb-length discrepancy
When children are born with a limb-length discrepancy, it does not usually manifest itself until the child is crawling or walking.
The causes are numerous, common causes are:
- Bone disease
- Infections that disturb bone growth
- Neurological conditions
- Joint inflammation or juvenile arthritis
- Trauma/injury which interrupts bone growth
- A tumor
In most cases the conditions are present at birth, and in some instances the cause could be completely unknown.
Signs/symptoms for limb-length discrepancy
The effects of a leg-length discrepancy can vary, often depending on the severity of the discrepancy. Common signs/symptoms include:
- Uneven sizes of the thigh bone, and shin bone.
- Difficulty walking, sometimes displayed in a limp or waddle.
- Easily fatigued
Limb length discrepancies can also elevate the risk for other conditions such as low back pain, hip pain, and scoliosis.
Treatment for limb-length discrepancy
Treatment for limb-length discrepancy ultimately depends on how severe the discrepancy is among other factors such as:
- Cause of the discrepancy
- Any underlying or neurological issues
There are various treatment options available depending on the severity.
Non-surgical treatment for limb-length discrepancy
For patients with a minor discrepancy in their limbs, and no angular deformity, non-surgical treatment is available as an option. This is because the risks of surgery outweigh the benefits.
For children who have not yet reached maturity, simply watching and waiting until growth is complete is an option. It’s possible that the discrepancy will continue to be minor or resolve itself as the child grows. For minor cases, doctors may recommend this as an option out of caution.
Your doctor may recommend an orthotic to see if it helps improve your child’s ability to walk/run. Insole may provide additional benefits here such as extra support, reducing back/joint pain caused by the discrepancy, as well as preventing a host of other conditions. A heel lift may be placed beneath the orthotic to help equal out the length discrepancy.
For a discrepancy that is a bit more severe, a doctor may prescribe a build up to the outside sole of a shoe to help even out the discrepancy. Measurements should be taken by a doctor and shoe modifications should be made to approved shoes by a certified Pedorthist.
When is surgery needed?
Surgical treatment for limb-length discrepancies are designed to:
- Slow the growth of the longer limb
- Lengthen the shorter limb
- Shorten the longer limb
Let’s examine these in detail.
Guided growth (epiphysiodesis)
Epiphysiodesis (guided growth) is a way to temporarily (or permanently) halt the growth of the longer limb. During this procedure the surgeon will make a small incision in the femur and upper shin to access the growth plate. Either by drilling the growth plate or placing small metal plates around the growth plate, this will halt growth of the limb. Once the plates are in, it’s best to check in every few months to ensure things are looking good and plan on a time to remove the plates.
Lengthening the shorter limb is often the preferred method here, in this scenario the surgeon will cut the bone of the shorter leg and then apply either an external fixator or internal device to lengthen the bone and correct the discrepancy.
External fixation is the traditional model of treatment, and has been used successfully for many years. After surgery to cut the bone, a scaffold-like frame is connected to the bones with pins. Lengthening begins about a week after surgery and is performed manually by either the patient or a family member turning a dial on the external fixator several times a day. The dial increases the space between the cut bones, allowing new bone to slowly form, while nearby muscles, soft tissue and skin adapts. The bone may be lengthened about 1 mm a day and about 1 inch per month.
While this has a history of success, it can be challenging and uncomfortable for some patients.
The above methods work for children who are still growing, for those who have reached maturity and are no longer growing, shortening the longer limb is an option.
In this scenario, doctors will remove a section of bone from the middle of the longer limb, while inserting a rod and screws to provide support to the bone as it heals. This can result in effects to the surrounding leg muscles and should not be used for significant discrepancies.
Insoles for limb-length discrepancy
For minor cases (less than ½” in difference) orthotics may be recommended to provide stability, help with balance, and prevent other conditions. Custom orthotics help by raising the lower leg to eliminate the discrepancy, this can make it easier for your child to walk, run, or do any other activity they would like. In some cases it is optimal to use an over-the-counter insole in combination with a heel lift. Insoles and orthotics also add support and stability which can keep your child comfortable as they grow.