Leg Length Discrepancy
Leg length discrepancy is a type of deformity that occurs when the growth of one leg has been stunted. This can occur after a trauma to the femur or tibia bone such as a break, tumor, or infection. The damaged bone may grow more slowly than the bone in the healthy leg, causing different lengths to occur. This deformity is usually noticed by parents as a child begins to crawl or walk. A child may be born with different leg lengths, or the condition may be caused by an illness or injury that develops over time. A slight difference in the length of the legs may not cause any symptoms. However, a significant limb length discrepancy may cause a limp and make it difficult to perform normal activities. A serious difference in the length of the legs can also be harmful to the hips and other bone structures as the person ages. Cosmetic limb lengthening surgery can help restore mobility and function for those with limb deformities or limb length discrepancy.
At least 90 percent of the population has some form of anatomic leg length inequality. Most have only a small difference, often around 5 mm, that never causes symptoms or requires treatment. Others have a larger discrepancy that affects walking, posture, or joint health and may benefit from medical evaluation.
What is Leg Length Discrepancy?
Also known as anisomelia, leg length discrepancy (LLD) is one where one of the lower limbs is longer or shorter than the other. This unequal length in the limbs can change an individual’s posture, gait, and movements completely. However, the difference in length varies widely from one person to the next, depending on the condition’s cause. The variation can range from a mere portion of an inch to numerous inches.
Additionally, there are two types of LLD. One is structural LLD, where there is a physical difference between the same bone in the limbs. The other is functional difference, where the bones may be of equal length, but the symmetry between the limbs is unequal. This is usually related to muscle tightness.
How Much Leg Length Discrepancy is Normal?
Not all discrepancy is unusual or a cause for worry. It may simply be a slight dissimilarity between the two sides of your body. This may not affect your wellbeing, health, or the quality of life you lead. For instance, a recent study showed that at least 32 percent of recruits to the military have a 0.5 to 1.5 cm discrepancy. This is quite normal.
Leg Length Discrepancy in Children
Leg length discrepancy is a condition that mostly appears when someone is still a child. In most instances, a child is born with this condition, and only a few acquire it when they get older. Your child may get LLD from injuries while playing or from various health conditions, including bone tumors, cerebral palsy, and diseases of the bone.
Because children are still growing, a discrepancy may not become obvious until changes in posture, gait, or activity level begin to appear. If your child has this condition, they may complain of the following symptoms:
- Back, knee, hip, and ankle pain
- Poor posture like extreme shoulder tilts
- Issues with walking
- Toe walking
- Limping
Leg Length Discrepancy in Adults
In adults, leg length discrepancy is often easier to recognize because the difference becomes more noticeable over time or begins causing symptoms, such as limping, back pain, or joint discomfort. Although most adults have this condition from birth or childhood, others can get it later on.
Adults may also develop functional leg length discrepancy as a result of neuromuscular conditions, arthritis, and chronic pain in hips, knees, ankles, or back, and sometimes even exercises. The most common type of LLD in adults is functional LLD, affecting your posture and alignment. However, for those born with this condition, structural LLD is often the most common type.
Causes of Leg Length Discrepancy
Leg length discrepancy can develop for several reasons, which generally fall into two categories.
- Congenital (Present at Birth)
- You were born with the condition that made one leg grow slower than the other or altered the alignment of the hips
- You were born with legs of unequal length, or the shinbones were bowed
- Acquired (Trauma or Injury)
- Something happened in your childhood that either affected the length of the bone in one leg
- Something happened in your childhood affecting the growth center of your bone
Some common causes include a fracture or an injury where the healing process caused an overgrowth of the bone or caused a slowed growth of the bone in one leg. Additionally, if you suffered from any bone diseases that damaged the growth plate, you may acquire this condition. Some treatments can also cause discrepancy by affecting the natural growth of the bones.
While congenital conditions and childhood injuries account for many cases, orthopedic specialists also evaluate several other medical and developmental factors that may contribute to leg length discrepancy.
Within these two circumstances, specific causes include:
- Congenital conditions, such as fibular hemimelia or hemihypertrophy, where one limb does not grow at the same rate as the other.
- Post-traumatic growth plate injury, where a fracture near a growth plate can cause the bone to stop growing early or grow at an abnormal angle.
- Prior orthopedic surgery, such as a hip or knee replacement, which can occasionally leave a minor leg length inequality.
- Bone infections such as osteomyelitis, or certain tumors, which can interfere with healthy bone growth during childhood.
The effects of leg length discrepancy extend beyond one leg being shorter or longer than the other. Over time, the body adapts to the imbalance, and those compensations can place additional stress on the joints and spine.
Symptoms and Long-Term Impact
When the legs are unequal in length, the body attempts to compensate, and that compensation can create secondary orthopedic issues, including:
- Pelvic tilt: one side of the hip sits lower than the other, which can contribute to lower back pain.
- Functional scoliosis: the spine may curve to balance an uneven hip foundation.
- Knee and ankle pain: the shorter leg often bears weight differently, which can lead to premature wear of the joints.
- A noticeable limp: a tip-toe gait on the shorter side, or a dipping motion when walking.
Left untreated, a significant discrepancy can contribute to early-onset arthritis and lasting structural changes in the spine.
Diagnosing Leg Length Discrepancy
Diagnosing leg length discrepancy involves confirming whether a true difference in bone length exists, identifying the underlying cause, and measuring the exact amount of discrepancy before treatment recommendations are made. Your orthopedic surgeon may use several methods to evaluate the discrepancy, including:
Imaging
You may need to take an x-ray, radiography, or any imaging your doctor deems necessary in most instances. These can give the exact measurement of your discrepancy and any fractures you may have due to stress on that part of the leg. Additionally, radiography can help differentiate the type of discrepancy you may have; functional LLD or anatomical LLD.
Direct Measuring
Your doctor can also use a measuring tape to differentiate limb length between two defined points. For instance, the orthopedic surgeon can measure between your lateral malleolus and inferior iliac spine. Two or more measurements are usually standard to ensure precision.
Measuring Blocks
This method is often common when diagnosing children. In this case, your doctor will put their hands on a bilateral anatomical structure of their choice and use visual assessment to tell the difference in the leg length.
If the leg length is unequal, the doctor will keep placing blocks of various heights until the leg length is equal. This can help tell how much more height you need to be added to reach the desired equal length.
Clinical Signs
There are symptoms and side effects of leg length discrepancy that a doctor can use for diagnosis. For instance, your doctor may instruct you to walk around the examination room. This can help tell if you are making up for the discrepancy in any way.
Additionally, pain in the back, knees, hips, and spine can also confirm your discrepancy. The imbalance in muscle forces in these areas is usually the culprit responsible for the pain. Another sign is fatigue due to the need to keep flexing your knee while moving to maintain a more leveled pelvis.
Treatment For Leg Length Discrepancy
Treatment depends on the size of the discrepancy, its underlying cause, your age, and whether the condition is affecting your mobility or quality of life. The most common treatment type is limb length discrepancy, or limb lengthening, surgery. This treatment is the best option for those with larger differences in the length of the limbs, usually above 1.5 centimeters.
Smaller discrepancies can often be managed without surgery. Your orthopedic surgeon will recommend the most appropriate treatment based on the degree of discrepancy, your symptoms, and your overall goals. Larger discrepancies may require surgical correction to restore alignment and balance.
Non-surgical management is often used for smaller discrepancies and may include:
- Shoe lifts: an internal or external lift on the shorter leg’s shoe can help level the hips.
- Physical therapy: targeted exercises to strengthen compensatory muscles and improve flexibility.
When a discrepancy is significant or causing pain, surgical correction focuses on the affected limb rather than both legs. Options include:
- Limb lengthening of the shorter leg using an internal lengthening nail such as the PRECICE nail system, which gradually grows new bone to restore symmetry. This is often preferred for adults because it restores balance without reducing overall height.
- Epiphysiodesis for growing children, which slows the growth plate of the longer leg so the shorter leg can catch up naturally over time.
- Bone shortening, in which a small section of bone is removed from the longer leg. It is effective but less common because it reduces the patient’s overall height.
The Correction Process with an Internal Lengthening Nail
For adult patients, the internal lengthening nail is a widely used modern approach. It avoids bulky external metal frames and supports a more comfortable recovery.
- Precision planning: using long-leg X-ray films, Dr. Mahboubian calculates the exact discrepancy. The femur and tibia proportions are analyzed so the knees and ankles align after surgery.
- The procedure: through minimally invasive incisions, the bone is cut (an osteotomy) and a telescopic motorized nail is inserted, then secured with screws for stability.
- The distraction phase: about a week after surgery, an external remote controller uses magnets to expand the internal nail by roughly one millimeter per day. As the gap opens, the body fills it with new bone tissue, a process known as distraction osteogenesis.
- Consolidation and recovery: once the legs are equal in length, lengthening stops and the new bone hardens. Intensive physical therapy during this phase helps maintain joint range of motion and muscle strength.
Why Choose The Height Lengthening Institute For Leg Length Discrepancy Surgery
At Height Lengthening Institute, every treatment plan begins with a comprehensive evaluation of your anatomy, symptoms, imaging, and goals. Dr. Shahab Mahboubian specializes in advanced limb reconstruction techniques and develops individualized treatment plans designed to restore balance, improve function, and support long-term mobility.
Patients choosing internal nail correction here can expect:
- Minimized scarring, since internal nail techniques use only small incisions.
- A focus on quality of life. Patients often report reduced back and hip pain once their gait is balanced.
- Comprehensive care, from the initial consultation through the final physical therapy session, tailored to your specific anatomy.
Every patient’s anatomy and treatment plan are different. These answers address some of the most common questions patients ask when considering treatment for leg length discrepancy.
Frequently Asked Questions
How long does the whole process take?
The lengthening phase depends on the size of the discrepancy. For a 3 cm difference, the distraction phase takes about 30 days. Full bone hardening, or consolidation, typically takes another three to six months.
Can I walk during the recovery?
Many patients are able to bear some weight and move with the help of crutches or a walker during recovery, though this depends on which bone is being lengthened and your surgeon’s guidance. Your care team will give you a specific weight-bearing plan and adjust it as new bone forms. Physical therapy throughout recovery helps you stay mobile and protect your joints.
Will my back pain go away?
Many patients find that back and hip pain eases once the legs are balanced and the gait is more even, because the body no longer has to compensate for the difference. Results vary from person to person, and some causes of back pain are unrelated to leg length. Your surgeon can help you understand what improvement is realistic for your situation.
Is this covered by insurance?
Coverage depends on your specific plan and whether the procedure is considered medically necessary. Correction for a documented discrepancy that causes pain or functional problems may be treated differently from purely cosmetic lengthening. Our team can help you review your options and the documentation your insurer may require.
Can you correct bow legs at the same time?
In some cases, an angular deformity such as bow legs can be addressed alongside a leg length discrepancy, since both relate to overall limb alignment. Whether this is appropriate depends on your anatomy and imaging. Dr. Mahboubian can evaluate this during your consultation and explain what a combined plan would involve.
What is the success rate?
Limb lengthening with an internal nail is a well-established procedure, and outcomes are generally favorable when patients follow their surgical and physical therapy plans. Individual results depend on factors such as the size of the discrepancy, bone health, and adherence to the recovery protocol. Your surgeon can discuss what to expect based on your specific case.
Is the internal nail permanent?
The nail stays in place while the new bone forms and hardens, which usually takes several months. Once the bone has fully consolidated, the nail has done its job and can often be removed in a minor follow-up procedure, though some patients choose to keep it in place. Your surgeon will recommend the right approach for you.
Is there an age limit for LLD surgery?
There is no single cutoff age, and treatment is tailored to the patient. For growing children, options like epiphysiodesis work with natural growth, while adults are usually candidates for internal nail lengthening once their bones have matured. Overall health and bone quality often matter more than age alone.
How do I know if my discrepancy is severe enough for surgery?
Surgery is generally considered when the difference is large enough to affect your gait, cause pain, or contribute to joint and back problems, often above roughly 1.5 cm. Smaller differences are usually managed without surgery. A consultation with imaging is the most reliable way to know what treatment fits your situation.
How do I start?
The first step is a consultation, where your medical history is reviewed and imaging is taken to measure the exact discrepancy. From there, Dr. Mahboubian creates a plan tailored to your anatomy and goals. You can contact Height Lengthening Institute to schedule your consultation.