Living with the sensation that one leg is shorter than the other isn't just uncomfortable—it can cause a domino effect of pain throughout your entire body. Whether you've recently noticed an uneven stride or have been dealing with any of the symptoms listed below, such as chronic lower back pain, you might be dealing with Leg Length Discrepancy (LLD).
But what exactly is LLD, how do you know which type you have?
What is Leg Length Discrepancy (LLD)?
Simply put, a Leg Length Discrepancy (LLD) is a condition where one leg is shorter than the other. While it sounds straightforward, the root cause of the imbalance can vary significantly. To effectively treat it, we must first understand the two primary categories: Structural LLD and Functional LLD.
Structural vs. Functional Leg Length Discrepancy
| Feature | Structural LLD | Functional LLD |
| The Root Cause | An actual physical difference in the length of the leg bones (femur or tibia). | The leg bones are equal in length, but alignment issues make one appear shorter. |
| Common Triggers | Genetics, childhood fractures, joint replacements, or bone infections. | Tight muscles, joint stiffness, pelvic tilts, or poor posture. |
| Typical Treatment | Heel raises, Insole foot raises like the Mesa HexLift), orthotics, or in severe cases, surgery. | Targeted stretching, physiotherapy, manual therapy, and posture correction. |
Note: In most cases of structural LLD, your body's soft tissues will attempt to compensate for the unevenness. This means a structural issue can go entirely unnoticed for years before suddenly triggering pain or functional issues. Structural LLD is often mistaken for a Functional LLD if not properly investigated and treated as such, with less improvement in symptoms.
What Causes Structural Leg Length Discrepancy?
We will focus on Structural LLD because that is the type that typically responds less to physiotherapy and therapies such as targeted stretching and more to the implementation of aids such as MESA HexLift.
Structural LLD can be present from birth (congenital) or develop later in life (acquired). The most common causes include:
-
Congenital Conditions: Some individuals are simply born with unequal leg bone lengths with no identifiable underlying cause.
-
Bone Fractures: Breaking a leg bone during childhood can disrupt the growth plate, causing that limb to grow shorter. Conversely, the healing process can sometimes overstimulate growth, making it longer.
-
Joint Replacement Surgery: Undergoing a hip or knee replacement can alter the effective length of the leg, particularly if the prosthetic positioning shifts the joint's natural center of rotation.
-
Bone Diseases or Infections: Conditions affecting bone density or growth, such as Perthes disease or osteomyelitis, can result in unequal limb lengths over time.
Identifying the Symptoms of a Short Leg
The symptoms of a Leg Length Discrepancy can vary widely depending on the size of the gap, your activity levels, and your individual biomechanics.
While differences under 10mm are incredibly common, discrepancies between 5mm and 20mm are actually the most frequently underdiagnosed. Unlike larger discrepancies (above 20mm) which produce highly noticeable changes right away, smaller structural imbalances tend to fly under the radar. However, even a minor discrepancy can cause persistent, low-grade strain that steadily worsens over time if left unaddressed.
No matter how large or small the difference, a short leg can induce a variety of compensatory symptoms throughout the body, including:
-
An Altered Gait: A visible limp, uneven stride, or a subtle "hip hitch" when walking.
-
Chronic Joint Pain: Persistent discomfort in the lower back, hips, knees, or ankles as they try to absorb uneven impact.
-
Structural Realignment: A noticeable pelvic tilt or the development of functional scoliosis (a sideways curve of the spine) as the body tries to keep your head level.
-
Muscle Fatigue and Spasms: Increased exhaustion, tight muscles, or painful spasms in the legs and lower back during prolonged standing or walking.
-
Recurring Soft Tissue Injuries: Stubborn, repetitive conditions like IT band syndrome, plantar fasciitis, or Achilles tendonitis caused by uneven loading.
The Bottom Line: Don't ignore minor discomfort. Discrepancies under 10mm may present subtly at first, but their repetitive toll on your joints and muscles means symptoms often intensify the longer they are left untreated.
If you suspect a structural LLD may be the cause of your symptoms, MESA recommends visiting the Get Calibrated˚ page for more information and to start your journey to getting answers.
0 comments