A Limb Length Discrepancy (LLD) is a noticeable difference in the length of your legs.
LLD’s are actually quite common, however, it is usually quite minor and we don’t even notice it.
When assessing the length of your legs, a difference greater than 1.5cm-2cm is reason to further investigate the cause.
What is a limb length discrepancy?
Limb length discrepancies can be caused by either structural or functional abnormalities.
This type of LLD due to a physical difference in the length of the bones between your ankle and your spine. This can occur due to an injury to the growth plates during childhood or genetic bone disorders.
The difference in leg length in this case is due to muscular weakness and/or limited flexibility in the hips, ankle, or feet.
What does a limb length discrepancy feel like?
An LLD may cause pain through both sides of the body at the ankles, knees, hips and back, as it tries to compensate for this abnormality.
It can also cause a noticeable limp when walking. Walking can also become tiresome and difficult for those with a limb length discrepancy, as a greater amount of energy is required to walk.
Common signs of a limb length discrepancy are
- visible difference in leg length (one leg shorter than the other)
- posture issues with tilted shoulders
- limping or toe walking
- hyperextended knee on the shorter side and bent knee on the longer side
- difference in the arch height between the left and right foot
What causes limb length discrepancies?
There are many causes for an LLD and these can be divided into 3 categories:
Shortening of a limb
This is the most common reason for a limb length discrepancy to form. This can occur due to a genetic disorder that affects growth, damage to the growth plate, bone infection, bone fractures and bone tumors.
Lengthening of a limb
This is a less common cause of LLD and can result from tumors in areas such as in the kidney, as well as septic arthritis, and fractures that haven’t healed correctly or from surgeries.
Issues within the spine or hip joint
Spinal misalignment or tilting of the pelvis in children can also cause limb length differences. In cases like this the LLD is considered to be a form of functional LLD.
Some other causes of LLD include:
- Juvenile Idiopathic Arthritis
- Cerebral palsy
- Club foot
Who does LLD affect?
A limb length discrepancy can affect anyone with one or more of the above mentioned causes. It is more commonly diagnosed in children with parents noticing a limp when their child walks.
However, limb length discrepancies can also be picked up in adult years through thorough assessment to help identify the cause of your knee, ankle or foot pain.
How are limb length discrepancies diagnosed?
The diagnosis of an LLD can be done in a number of ways, which include:
Having an x-ray or computed tomography (CT) scan of your legs allows for accurate measurements to be taken of the legs to determine the size of the discrepancy.
Both legs can be measured in a number of ways from the hips to ankles. Each segment is also measured to determine where exactly the discrepancy is located. For example, we can measure from the hip to the knee, or the knee to the ankle to see which segment has the discrepancy. In some cases, to assist with the measurements, wooden blocks are placed under the foot of the shorter side until the hips are even.
Observing the way you walk can assist in identifying a limb length discrepancy, with markers such as limping and the position of the knees, hips and shoulders being assessed. Here at Watsonia Podiatry, we use our Zebris treadmill to record the way you walk and can identify if there is an instability in your hips.
How is an LLD treated?
Treatment of a limb length discrepancy can be either non-surgical or surgical. The treatment type is dependent on a variety of factors including:
- the age of the patient
- the severity of the LLD
- the level of pain
- the cause of the LLD
Non-surgical treatment – Heel raise and custom foot orthotics
Placing a heel raise on the shorter side to ‘even up’ the hips is commonly used in the management of a limb length discrepancy. This treatment is useful for discrepancies that are less than 2.5cm and work really well in conjunction with custom orthotics. The use of custom orthotics can allow the feet and lower limbs to function more efficiently. Custom orthotics can also help address any pain that you may be experiencing.
For more details on custom orthotics here at Watsonia Podiatry, check out our article – “Orthotics 101 – Your Guide to Everything Orthotics“.
Surgical treatment of LLD has 3 outcomes:
Shortening the longer leg – Making the longer leg shorter is only done when the person has fully grown. This type of procedure involves removing a section of bone from either the thigh bone or shin bone. Metal rods are then used to fix the new bones together while healing occurs.
Lengthen the shorter leg – This type of surgery is not performing regularly and is typically reserved for considerable limb length discrepancies. Making a leg longer can be done by external or internal fixation. Both of these options use metal rods that gradually elongate the bone over time, usually taking many months to achieve the required result.
Stop the longer side from growing by epiphysiodesis – Interfering with one or two of the growth plates in the leg is used to stunt or stop the growth of one leg. Using this method aims to have two legs of the same length by the time the child has finished growing, which is generally in the late teens.
If you or your child are experiencing pain or discomfort that may be caused by an LLD, or any other foot or lower limb pain, book an appointment with the team here at Watsonia Podiatry. Our team of superstar podiatrists are here to help relieve you of any pain and have your feet being the best they can be. You can book your appointment by calling us on 03 9432 2689 or book online here.