Have you ever noticed that one leg feels longer than the other? Do you experience recurring hip, knee, or back pain that seems to have no obvious cause? A difference in leg length—known as a limb length discrepancy (LLD)—may be contributing to your symptoms.
Although small differences in leg length are common, a more significant discrepancy can affect the way you walk and place stress on the feet, ankles, knees, hips, and lower back. A podiatrist can evaluate how a limb length difference affects your gait and, in many cases, help improve comfort and function with custom orthotics and shoe modifications.
What Is Limb Length Discrepancy?
Limb length discrepancy occurs when one lower extremity is shorter or longer than the other. The difference may be:
- Structural: The bones of one leg are actually shorter than those of the other.
- Functional: The legs may be the same length, but factors such as foot mechanics, joint position, muscle imbalance, or pelvic alignment create the appearance or effect of a leg-length difference.
Some people are born with a limb length discrepancy, while others develop one as a result of trauma, surgery, growth abnormalities, arthritis, or other medical conditions.
How Can a Limb Length Difference Affect the Body?
Even a relatively small discrepancy can alter the way a person walks. The body naturally compensates for differences in leg length, but these compensations may place additional stress on various parts of the lower extremity.
Possible symptoms include:
- Foot or ankle pain
- Knee pain
- Hip discomfort
- Low back pain
- Muscle fatigue
- Uneven shoe wear
- Recurrent injuries on one side of the body
- Changes in walking or running mechanics
A limb length discrepancy may also contribute to abnormal foot mechanics. For example, a person may overpronate or supinate to compensate for the difference, potentially placing increased stress on the feet and ankles.
How Do Podiatrists Evaluate Limb Length Discrepancy?
A podiatrist begins with a detailed history and physical examination. This may include:
- Evaluation of standing posture
- Assessment of the pelvis and lower-extremity alignment
- Examination of the feet and ankles
- Gait analysis
- Evaluation of shoe wear patterns
- Measurement of the lower extremities
- Assessment of leg and foot mechanics
In some cases, imaging studies may be recommended to accurately measure a structural limb length difference. A thorough evaluation is important because not every apparent leg-length discrepancy is caused by a difference in bone length.
How Can Orthotics Help?
Custom orthotics can be an important part of managing certain limb length discrepancies. Depending on the cause and severity of the discrepancy, a podiatrist may recommend a custom shoe lift or heel lift to help compensate for the shorter limb.
The goal is not always to completely correct the difference. Instead, treatment is often individualized to help improve comfort, balance, and function while reducing excessive stress on the body.
Orthotic treatment may include:
Custom Heel or Shoe Lifts
A lift can be incorporated into an orthotic or placed inside the shoe to provide additional height to the shorter side. The amount of correction depends on the individual patient and the size of the discrepancy.
Full-Length Orthotics
A full-length custom orthotic can provide support throughout the foot while incorporating a lift or correction designed to help accommodate the limb length difference.
Custom Shoe Modifications
For larger discrepancies, an external shoe modification may be recommended. This may involve adding material to the sole of the shoe to provide additional height.
Correction of Associated Foot Problems
Sometimes the apparent limb length difference is influenced by foot mechanics. An orthotic may help control excessive pronation, improve arch support, or address other biomechanical issues that contribute to uneven loading.
Why Gradual Correction May Be Important
When a person has lived with a limb length discrepancy for many years, the body may adapt to the difference. Correcting the discrepancy too quickly or too aggressively may create new discomfort in the feet, knees, hips, or back.
For this reason, a podiatrist may recommend a gradual approach, particularly when the discrepancy is significant or longstanding. The treatment plan should be individualized based on the patient’s symptoms, physical examination, activity level, and overall biomechanics.
Do You Need a Custom Orthotic?
Over-the-counter shoe inserts may be helpful for some foot conditions, but they are not designed to address every type of limb length discrepancy. Custom orthotics can be specifically designed to account for the individual’s anatomy and biomechanical needs.
A podiatrist can determine whether a custom orthotic, heel lift, shoe modification, or combination of treatments is appropriate.
When Should You See a Podiatrist?
Consider scheduling an evaluation if you have:
- Persistent pain on one side of your body
- Recurrent foot, knee, hip, or back problems
- Noticeably uneven shoe wear
- A known difference in leg length
- A history of leg or foot surgery
- A prior fracture involving the lower extremity
- Difficulty walking or running comfortably
The Bottom Line
Limb length discrepancy can affect more than just the legs. It may influence the way you walk and place stress on the feet, ankles, knees, hips, and back. A podiatrist can evaluate the underlying cause of the discrepancy and determine whether orthotics, shoe lifts, or other treatments may help.
If you are experiencing pain or difficulty walking because of a suspected limb length discrepancy, a comprehensive evaluation by a podiatrist can be an important first step toward improving your comfort and mobility.
By Dr. Yavor Geshev, DPM, FACPM, DABFAS, DABPM
