Limb Length Discrepancy (LLD)
What is limb length discrepancy?
Limb-length discrepancy refers to unequal lengths of arms or legs. Although up to one-third of people may have a difference of 1 cm or less between their right and left legs, these small variations are usually not noticeable and don't require intervention. Meanwhile, differences in arm length are even less obvious and do not impede arm function.
However, substantial limb-length disparities in children can significantly impact their movements, leading to a limp while walking, difficulties with running, back or hip pain, and difficulties with daily activities and playing compared to their peers. These discrepancies may occur at birth or develop over time due to injury, illness, or the need for limb lengthening procedures.
Types of limb-length discrepancies
- Structural limb-length discrepancy
This occurs when one bone in an arm or leg is shorter than its corresponding bone in the other limb.
- Functional limb-length discrepancy
In this case, the bones in both arms or legs are of equal length, but a joint contracture, such as limited mobility in a knee, hip, elbow, or other joints, causes asymmetry.
Symptoms of limb-length discrepancies
Leg-length discrepancies have a more significant impact on children and may require treatment. The symptoms of this condition can vary from child to child and may include the following:
- Uneven lengths of the thigh bone (femur) and shin bone (tibia), with the possibility of the smaller lower leg bone (fibula) being affected as well.
- Difficulty walking, such as limping, waddling, or walking on the toes of the shorter leg.
- Increased fatigue due to the extra effort required to move.
- An increased risk of other related conditions, including low-back pain, osteoarthritis, and scoliosis.
When limb-length discrepancies affect legs, the symptoms are more noticeable, and treatment is often needed.
Causes of limb-length discrepancies
A variety of factors can cause limb-length discrepancies, including:
- Bone diseases or dysplasias include Ollier disease, neurofibromatosis, and multiple hereditary exostoses.
- Bone infections disrupt growth plate development.
- Neurological conditions, such as cerebral palsy, spasticity, and paralytic disorders.
- Inflammatory joint conditions, such as juvenile idiopathic arthritis.
- Trauma or injury to a bone that leads to healing in a shortened position or faster growth on one side, particularly in the case of compound fractures near or in the growth plates.
- Congenital conditions, such as clubfoot, developmental dysplasia of the hip, hemihyperplasia, and proximal femoral focal deficiency, impact growth on one side of the body or in a specific bone.
- Tumors or tumor removal surgery can temporarily or permanently affect nearby growth.
In many cases, these causes are present at birth, but the limb-length discrepancy may not be noticeable until later in childhood. In some cases, the cause remains unknown.
How is a limb-length discrepancy diagnosed?
The first step in diagnosing a limb-length discrepancy is to undergo a complete medical history evaluation and a physical examination by an orthopedic surgeon. During the exam, the doctor will measure the limbs to determine the extent of the difference in length.
If a leg length discrepancy is present, the doctor may observe walking patterns and compensate for the difference by having the individual stand with a block under their shorter leg to realign their hips and body.
The doctor may also request an x-ray or imaging test to measure the discrepancy accurately.
How are limb-length discrepancies treated?
The treatment for limb-length discrepancies varies depending on the extent and cause of the discrepancy. In some cases, no treatment services may be necessary, especially if the difference is small and does not cause any symptoms or functional problems. However, if the discrepancy is significant and affects the individual's mobility, the following treatments may be recommended:
- Shoe lifts: Correct minor limb-length discrepancies by wearing a shoe lift in the shorter limb's shoe.
- Orthotics: For larger discrepancies, custom orthotics, such as ankle-foot orthotics (AFOs) or knee-ankle-foot orthotics (KAFOs), can help distribute weight and support the limb.
- Physical therapy: Physical therapy can help improve strength, flexibility, and balance and reduce pain and discomfort caused by the discrepancy.
- Surgery: Recommend surgery to correct the discrepancy in severe cases. This may involve lengthening or shortening bones, fusing joints, or realigning bones.
The type of treatment will depend on the individual's age, health, and the extent of the discrepancy. A doctor or an orthopedic specialist can advise on the best course of treatment based on a thorough evaluation of the individual's specific case.
How we can help:
If LLD is caused by differences in bone length, strategies like heel lifts and shoe modifications can be added.
