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What is Leg Length Discrepancy and How is it Measured?

What is Leg Length Discrepancy (LLD)?

LLD means Leg Length Discrepancy, which means unequal leg length. It is also referred to as leg length inequality (LLI). It is a situation whereby the two legs of a person are not equal. One is longer than the other.

What is Leg Length Discrepancy and How is it Measured?

Studies have revealed that most of the people in the world have unequal leg length of one leg being 2 cm shorter than the other. This is not often noticeable as the difference is quite insignificant. However, there are some very rare situations whereby this difference can be more than 2 cms with some people. If the difference is more than normal, the person develops a deficiency, requiring a medical attention.

Leg length discrepancy (LLD) of more than 2 cms usually begins with a limp. Patient’s gait becomes abnormal, leading to constant stress to exert so much energy on the shorter leg so it can perform like the other. The person will be constantly tired out from his/her efforts.

Leg length discrepancy (LLD) can be treated, whether it is a natural condition or caused by an injury. Treatment is usually directed to the pelvis, hips and lower back. A person who discovers he has leg length discrepancy (LLD) should consult an orthopedic surgeon to provide guidance on how to go about the treatment.

If leg length discrepancy (LLD) is not treated on time, it can lead to other malfunctions in the body like scoliosis, lower back pain, arthritis, etc… Therefore treatment should be adequately given. With on time treatment, children with leg length discrepancy (LLD) will do better without any cosmetic defects or lingering defects.

Is it Normal to Have One Leg Longer than the Other?

Leg length discrepancy (LLD) is a consequence caused by imperfect alignment of pelvis or sometimes one leg grows longer than the other one. Studies have indicated that many people in the world have leg length discrepancy (LLD) of 2 cms or lower. As the difference is not very significant it usually goes unnoticed.

What is it Called When You have One Leg Shorter than the Other?

When one of the legs is shorter than the other one it is scientifically called as leg length discrepancy (LLD) or Leg Length Inequality (LLI). If the leg length discrepancy (LLD) is more than 2 cms then medical attention is required for the child as it can affect the child’s wellbeing and his/ her life quality.

How is Leg Length Discrepancy Measured?

To measure leg length discrepancy (LLD), the following methods should be adopted:

  • Observation and palpation method for leg length discrepancy (LLD) is a simple method that has often yielded good results. The doctor generally observes the way you walk and feels your body structure to determine if the person has leg length discrepancy (LLD) or not. With this method, you can actually tell if a person has leg length discrepancy (LLD), but cannot determine the extent. So, other alternative methods are needed to support your findings.
  • Medical history checkup. The surgeon obtains information from the patient or guardian about the child’s/ patients’ medical background. Such as whether the person has had any injury or not.
  • Leg measurement to determine leg length discrepancy. The patient’s legs can as well be measured to determine the extent of the difference. This is done using a tape measure.
  • X-Rays. The surgeon can alternatively carry out an X-ray of the lower extremities, hips, and backbones. The radiographs produced will tell if the patient has leg length discrepancy (LLD) or not.
  • CT or CAT Scan for leg length discrepancy (LLD) is another method of measuring leg length discrepancy (LLD) is through the use of Computerized Tomography Scan (CT Scan). This will scan the bone structure and other soft tissues so that the doctor can detect if leg length discrepancy (LLD) is present. This method is often regarded as giving more reliable results than X-rays.
  • In the gait analysis for leg length discrepancy (LLD) the patient’s gait can also be analyzed/ measured by overall study of the movements, mechanics and muscles of the body using infrared cameras and other instruments in a laboratory to observe the gait. This analysis is able to show the presence of leg length discrepancy (LLD) but cannot tell the extent.

Types of Leg Length Discrepancy (LLD)

Leg length discrepancy (LLD) has been classified into three parts. Namely: Structural leg length discrepancy (LLD), Functional leg length discrepancy (LLD), and Environmental leg length discrepancy (LLD).

  1. Structural Leg Length Discrepancy (LLD): Structural leg length discrepancy (LLD) is hereditary in nature. A person with structural leg length discrepancy can be detected if the person has symmetrical pelvis, and the sacroiliac joints and the discrepancy is because of one leg is longer than the other one. Anterior and posterior X-ray of the pelvis is the best way to know if a person has structural discrepancy. Tape measure of the leg, starting from the hip, can also tell this.
  2. Functional Leg Length Discrepancy (LLD): When a person has sacroiliac joint dysfunction, it is usually referred to as functional leg length discrepancy (LLD). In functional leg length discrepancy (LLD), one leg seems longer than the other. The dysfunction of the sacroiliac must be treated and returned to its normal condition, then further determine if there is presence of structural leg length discrepancy (LLD) by measuring the length of the leg. If the pelvis is symmetrical, then structural leg length discrepancy (LLD) is present, and if not, the leg discrepancy is functional.
  3. Environmental Leg Length Discrepancy (LLD): This is a situation whereby a person can develop Leg length discrepancy (LLD) by running or walking on uneven surfaces such as walking or running on the beach, rocky ground, desert, etc… Also, constant wearing of shoes which are worn out can cause a person to develop environmental related leg length discrepancy (LLD). It may also be attributed by the existence of functional or structural leg length discrepancy (LLD).


  1. Cleveland Clinic. (2021). Leg Length Discrepancy (LLD) https://my.clevelandclinic.org/health/diseases/17771-leg-length-discrepancy-lld
  2. OrthoInfo. (2021). Limb Length Discrepancy https://orthoinfo.aaos.org/en/diseases–conditions/limb-length-discrepancy
  3. National Center for Biotechnology Information (NCBI). (2021). Limb Length Discrepancy https://www.ncbi.nlm.nih.gov/books/NBK542264/

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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 28, 2023

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