Leg Length Discrepancy and Pelvic Tilt: Orthopedic Treatment with Insoles and Correction of Leg Length Discrepancies

Leg length discrepancy (ICD code: Q72.9) is the medical term for a difference in the length of the legs. Diagnosis and treatment fall within the scope of orthopedics. The difference refers to the length of the legs from the hip to the foot. An estimated 10–30% of people have this difference.

An estimated 10–30% of people have this difference.

A normally proportioned skeleton with leg bones of equal length. This allows the pelvis and spine to maintain their physiological alignment and stability. © Alexandr Mitiuc / Fotolia

As long as the discrepancy is only slight, no treatment is necessary. With a difference of just 1 to 2 millimeters, the body can still compensate for the discrepancy on its own.

Treatment is necessary when the leg length discrepancy exceeds a certain threshold. The following applies:

• more than 0.5 cm leg length discrepancy in children
• and in adults, more than 1 cm. 

Leg-length discrepancies in children often continue to change as they grow. Nevertheless, they must be monitored and checked regularly. Many people are affected by a leg-length discrepancy. In mild cases, no symptoms are expected. The body is still able to compensate for the difference in these cases. In more severe cases, it is important to initiate the appropriate treatment promptly to prevent long-term damage.

The skeleton and the musculoskeletal system, including

• bones,
• joints,
• muscles, and
• tendons

are unique to each individual. However, they always follow physiological—that is, naturally healthy—principles. This includes the body’s structure, which is organized around

• the trunk (upper body),
• the axes of the limbs (arms and legs), and
• the head.

Changes in joint positions, axial alignment, and asymmetries have consequences for the entire system.

The effects can be serious, especially on the spine. When the legs are of different lengths, the pelvis shifts toward the shorter side. It tilts out of its horizontal position, and thus a leg-length discrepancy usually also results in pelvic obliquity. The pelvis sits slightly higher on the side of the longer leg.

This also affects the spine. It curves sideways, resulting in mild or severe scoliosis (spinal curvature).

Legs of different lengths can have various causes. There are congenital and acquired forms of leg length discrepancy. These can be divided into two categories:

• The anatomical or structural form: In this case, the bones are actually longer or shorter than those in the other leg.
• Thefunctional form: Here, muscle shortening (contractures) in the hip and knee cause the difference in length. Muscles that are constantly tense can also shift the alignment of the joints. As a result, one leg appears shorter on one side.

If a corresponding underlying condition is already present in a newborn, this is referred to as a congenital leg length discrepancy. Examples include:

• Vascular anomalies
• Clubfoot
• Clubfoot
• Partial gigantism
• Hemiatrophy (unilateral tissue atrophy)
• Malformations and
• skeletal disorders (exostosis).

Joint disorders or limitations in joint mobility can also trigger the condition

An acquired leg-length discrepancy develops over the course of a person’s life. Possible causes include:

• Accidents
• Bone fractures
• Infections
• Paralysis
• Radiation damage
• Tumors
• Long-term immobilization
• Poor posture and
• uneven weight-bearing.

Leg fractures during the growth phase can impair the cartilaginous growth plates of the fractured bones.

Specialized bone cells are responsible for bone growth. Disruptions can cause the bone cells responsible for growth to be more active in one leg than in the other. Excessive longitudinal growth can also result in leg length discrepancy. However, these differences often resolve spontaneously as the child develops. Once growth is complete, the body no longer spontaneously corrects differences in leg length. The habitual compensations or misalignments of the spine and joints then continue to progress.

The musculoskeletal system is subjected to increased strain when there is a significant difference in leg length. The body must compensate for the difference in length. As a result, the hip area and the spine shift. The tilt and rotation of the pelvis are compensated for by an increased forward curvature of the spine (lordosis).

In many cases, this results in a tilted shoulder on the side of the body where the leg is longer. The head also often tilts sideways toward the shorter leg.

Pain often occurs at the junction of the lumbar spine and the sacrum. Other possible symptoms include

• chronic back pain,
• discomfort and pain when standing and walking, as well as
• headaches and jaw pain caused by muscle tension.

On the right, a healthy spine; on the left, a laterally curved spine (scoliosis) due to a leg length discrepancy © Koterka Studio | AdobeStock

A serious consequence of a leg-length discrepancy can be the development of scoliosis (spinal curvature). It develops when the hip bone is displaced due to the leg-length discrepancy. The spine must curve to the left to allow the head to remain upright.

This process can have serious consequences. There are small joints between the bony vertebral processes. These can become misaligned when the vertebrae bend against one another. This is referred to as a facet joint blockage. Possible consequences include

• painful inflammation,
• reduced mobility of the spine, and
• nerve compression in the spinal region.

The sacroiliac joints are located in the pelvic region. These are the two joints where the sacrum is attached to the pelvic ring. They can become misaligned, which severely impairs mobility in the pelvic region. The two pubic bones can also be painfully affected.

Anatomical Structure of the Hip Joint © Henrie / Fotolia

A significant and persistent leg length discrepancy leads to changes in posture. The spine is permanently affected. The vertebrae and intervertebral discs wear out more quickly due to the curvature, increasing the risk of osteoarthritis.

Through a physical examination, the doctor determines whether the pelvis and spine are misaligned. To do this, the doctor palpates the iliac crests and the spine.

In addition, the doctor measures the length of the legs with a measuring tape. They place it on a palpable bony prominence on the thigh bone at hip level. The length is measured down to the outer ankle.

An X-ray or ultrasound (sonography) provides a more detailed picture. A precise analysis can be performed using three-dimensional spinal measurement. This allows the extent of the spinal curvature and pelvic misalignment to be determined. A special video procedure is used for this purpose.

A computer can then calculate the height at which the shoe insert must be made. This shoe insert compensates for the leg length discrepancy.

The diagnostic process must determine whether there is an actual leg length discrepancy or whether it is a functional discrepancy. A functionally based leg length discrepancy is generally treated differently than an anatomical leg length discrepancy.

Depending on the type and cause of the leg length discrepancy, treatment approaches include either

• physical therapy,
• compensation for the leg length discrepancy using orthopedic shoes, or
• surgery.

In cases of functional leg length discrepancy, physical therapy and intensive soft tissue treatment are often initiated. In some cases, surgical intervention on the soft tissues may also be indicated.

In cases of anatomical leg length discrepancy, orthopedic shoe inserts are often sufficient for correction. The earlier the diagnosis is made, the greater the chances of successfully correcting the leg length discrepancy. Insoles raise the shorter leg and help correct pelvic misalignment.

The effect of orthopedic shoes stems from the raised heel, which can compensate for a difference of up to 12 cm. If the difference is very significant, various orthopedic procedures may be used.

For adolescents still growing, for example, a minimally invasive procedure can be used to slow the growth of the longer leg. The growth plate in the leg must still be open for this to work, so this method is no longer possible once growth has stopped.

Once growth has stopped, there is another effective method. Using a special surgical technique, the shorter leg can be gradually lengthened. It extends by about one millimeter per day.

What is a leg length discrepancy?

A leg length discrepancy occurs when one leg is longer or shorter than the other. The difference can be anatomical, resulting from varying leg lengths, or functional, caused by muscular misalignments. Depending on the severity, it can lead to pelvic obliquity or spinal curvature.

What causes a leg length discrepancy?

The most common causes of a leg length discrepancy include congenital abnormalities, growth disorders, contractures, diseases of the joint structures, or changes following total hip replacement (THR). Functional leg length discrepancies and those caused by muscle-related postural misalignment are also common.

What symptoms does a leg length discrepancy cause?

Typical symptoms of a leg length discrepancy include back pain, discomfort in the hip and pelvis, an asymmetrical gait, and changes in posture. A difference in leg length can also affect the body’s biomechanics and, over time, contribute to scoliosis or osteoarthritis.

How is a leg length discrepancy diagnosed?

A leg length discrepancy is initially assessed through a physical examination. This may be supplemented by an X-ray and measurement techniques accurate to the millimeter. Landmarks such as the anterior iliac spine or the anterior superior iliac spine help in assessing leg length and pelvic alignment.

How is a leg length discrepancy treated?

Treatment for a leg length discrepancy depends on the cause and extent of the condition. Minor discrepancies are often corrected with shoe inserts or a raised insole. For larger differences, or if the leg length discrepancy requires treatment, an orthopedic specialist may recommend surgical procedures to correct the discrepancy. The goal is to restore a normal gait and prevent long-term symptoms.