Leg Length Discrepancy: Surgical Options

Leg length discrepancy is more common than you may think. When the discrepancy measures more than 20 mm, most doctors recommend having a complete evaluation, though. After all, length discrepancy can bring about issues with posture and walking, causing hip and back pain.

What Is Leg Length Discrepancy?

Leg length discrepancy, also known as anisomelia, means that one leg is longer than the other, measured from the hip to the heel.

In most cases, the bones affected are the tibia (shinbone) and the femur (thighbone).

What Causes Leg Length Discrepancy?

The femur and tibia growth happens around the so-called growth plates. Growth plates are cartilage areas located between the trumpet-shaped part of the shaft of the bone (the metaphysis) and the rounded end (the epiphysis).

break in a child’s bone right at the growth plate, for example, can cause permanent damage, which may slow or stop the growth in that area altogether. Hence, the other leg may grow faster than its counterpart, and a difference in length will develop over time.

Conditions that may affect the growth plates are congenital diseases (present at birth) or acquired conditions, including trauma, broken bones, degenerative bone disorders, or joint replacement surgery (total hip arthroplasty).

Conversely, a broken bone in a child that does not involve the growth plate could cause it to grow faster for several years after healing. Hence, the affected limb will become longer than the bone on the opposite side of the body.

Also, bone infections such as osteomyelitis, juvenile arthritis, bone tumors, and bone cysts in growing children can cause a significant limb length discrepancy. Moreover, cerebral palsy, polio, and other neuromuscular disorders can cause problems with a child’s hip alignment and overall posture. This is known as functional limb-length discrepancy.

Even though the leg bones are equal in length, it may seem like one leg is longer than the other.

What Are the Signs and Symptoms of Leg Length Discrepancy?

The effects of leg length discrepancy can vary from patient to patient. They depend on the cause and the extent of the difference (measures).

Compared to different arm lengths, leg discrepancies are more likely to affect a child’s day-to-day activities, including their normal posture and walking. If one leg is longer than the other, children can present with passive structural modifications, such as lumbar scoliosis and changes in muscle length to compensate.

Indeed, beyond 20 mm, passive structural changes give way to alterations in the hip, knee, and ankle axis. Hence, your child may present a noticeable limp or display a toe walk on their short side. This can result in joint stiffness or dislocation. Also, it could lead to arthritis as an adult.

Most commonly, patients will present with back/hip pain, sciatica problems, and fatigue from the imbalance in muscle forces near the hip, knee, and spine.

How Is the Diagnosis of Leg Length Discrepancy?

Discrepancies are sometimes detected when a child undergoes a screening at school for the curvature of the spine (scoliosis). During the exam, your doctor will closely observe your child’s gait (the walking pattern).

Young children usually compensate for a lower limb length discrepancy by walking on their toes or flexing one knee.

Commonly, the doctor will measure the discrepancy with your child standing barefoot. The doctor will place a series of measured wooden blocks under the short leg until the hip bones are completely level.

Sometimes, an X-ray is taken with your child standing with the wooden blocks in place to evaluate whether the pelvis is truly level. This can also determine whether any abnormal spinal curvature quickly responds to the discrepancy correction using the wooden blocks.

Palpation and visual assessment of the iliac crest, together with wooden blocks, are best to differentiate an anatomical from a functional leg length discrepancy.

Your doctor may also order a scanogram instead of, or in addition to, a traditional X-ray. A scanogram is a special type of X-ray that focuses on three images (hips, knees, and ankles) and a ruler to assess the length of the bones in the legs. In some complex cases, your doctor may need CT scans to measure the limb length discrepancy, though.

Also, if your child is still growing, your doctor will likely keep a close eye and repeat the examination and imaging studies every 6 to 12 months. It is important to see if the discrepancy increases or remains the same.

What Are the Treatment Options for Leg Length Discrepancy?

The treatment will depend on your child’s age (and how much growth they have to go) and the size of the leg length discrepancy.

Treatment is usually nonsurgical for patients with minor discrepancies (less than 20 mm) and no angular deformities. This also applies to functional leg length discrepancies.

Because the risks of surgery may counterbalance the benefits, surgical treatment to even out small differences in leg length is not usually recommended.

Indeed, patients with underlying neurologic disorders may benefit from their weaker leg being slightly shorter than the stronger one. This allows the child to quickly clear the weaker leg when they swing it during walking.

Also, if your child is still growing, and the discrepancy is less than 20 mm, your doctor may recommend close observation until your child’s growth is complete. During this period, your child will have regular check-ups to determine whether the discrepancy increases or remains the same.

A minor variation in leg length can be tolerated or quickly fixed by wearing a small lift in one shoe.  This lift therapy should be implemented slowly in small increments. After all, shoe lifts are inexpensive and can be easily removed if they are not effective.

What Are the Surgical Options For Leg Length Discrepancy?

Moderate cases (30-60mm) should be treated in a personalized way, considering surgical intervention. Severe cases of leg length discrepancy (>60mm) should always be surgically corrected, though.

The surgical options include induced slowing of growth by blockade of the epiphyseal plates around the knee joint, or leg lengthening with osteotomy procedures.

Sometimes, in patients with full skeletal maturity, limb shortening by bone resection procedures is preferred.


In children who are still growing, epiphysiodesis surgically slows or stops the growth at the growth plates in the longer leg.

Epiphysiodesis is a simple surgical procedure that can be performed in two ways:

  • The orthoapedic surgeon may scrape or drill the growth plate to stop further growth. The leg length discrepancy will gradually lessen as the opposite leg catches up.
  • Your doctor may place metal staples, or a metal plate with screws, at the sides of the growth plate to stop or slow down the growth. These metal implants are later removed once the discrepancy is fixed.

The main goal is to reach equal leg length by the time growth is over— at age 16 for boys and 14 for girls, on average, though this can vary. The downside of epiphysiodesis includes the possibility of a slight over-or under-correction of the leg length discrepancy.

Lower Limb Lengthening

Owing to their complexity, limb lengthening procedures are reserved for patients with considerable discrepancies greater than 40-50mm. The lengthening procedure can be performed either externally or internally.

In external lengthening, the doctor cuts the bone of the shorter leg into two segments. Then, he surgically applies an external fixator to the leg. The external fixator is a scaffold-like metal frame known as Ilizarov apparatus that sits outside the leg. It is connected to the bone with the help of pins, wires, or both.

The lengthening process begins nearly 5 to 10 days after surgery and is performed manually. The patient himself or a family member turns the dial on the fixator several times each day, under doctor’s orders, of course.

Every turn of the dial causes the bones to gradually pull apart so that new bone grows and fills in the space created. Muscles, tendons, and skin will adapt as the leg slowly lengthens.

The bone can lengthen 1 mm per day or approximately 1 inch per month.

Risks and complications of external lengthening include:

  • Infection around pin sites.
  • Stiffness of the joints above and below the bone being lengthened.
  • Over- or under-correction of the bone’s length.
  • Failure of the bone to properly consolidate into strong new bone.

What Is the Fitbone System?

The Fitbone system is a type of internal lengthening. It is a newer, safer, more comfortable, and effective way of lengthening the bones.

In this procedure, the orthopaedic surgeons cut the bone in the shorter leg and surgically implant an expandable metal rod inside the bone. The rod is an adjustable intramedullary nail that lengthens gradually in response to an external electric or magnetic motor.

As the rod lengthens, the end of the bones are gradually pulled apart, and new bone grows in-between. The rod provides both stability and alignment to the bone as it lengthens.

The potential advantages are:

  • Fewer scars.
  • Higher activity level during lengthening consolidation.
  • Faster rehabilitation.
  • Less risk of neurovascular compromise due to wire or screw insertion.

Since no external fixator is used in internal lengthening, there is less risk of infection too!

External and internal lengthening take several months to complete and require regular follow-up visits to the doctor’s office. This includes extensive rehabilitation and physical therapy.

Lower Limb Shortening

In patients who are done growing, the longer limb may be shortened to even out the leg lengths. In this procedure, the doctor removes a section of bone from the middle of the longer limb and inserts metal plates and screws or a rod to hold the bone while it heals.

Major limb shortening may weaken the leg muscles, so it is not recommended for considerable lower limb length discrepancies.

  • A maximum of 2 inches can be shortened in the tibia.
  • In the femur, no more than 3 inches can be shortened.

How Much is Length Discrepancy Correction Surgery?

Leg length discrepancy surgery cost with the Fitbone method depends on several factors.

Our team will carefully analyse your request. If you would like to receive an approximate quote, please complete the contact form.


Bachelor in Medicine and Surgery (1979, University of Barcelona, Spain). Specialist in Orthopedic and Trauma surgery (1982).

Member accredited by the German company Wittenstein for the use of the Fitbone technique.

Head of the bone reconstruction and lengthening unit. Dexeus University Hospital (since 2013).

Director of the Catalan Institute of Traumatology and Sports Medicine (ICATME) since March 2020.

Member of the board of directors of the International Limb Lengthening and Reconstruction Society.

Doctor Ignacio Ginebreda speaks French and English fluently.


– Award of excellence ‘Best scientific publication’ for the article Surgical technique and outcomes for bilateral humeral lengthening for achondroplasia: 26-year experience (2020).

– Award of Excellence at the Congress of the Spanish Society for External Fixation and Reconstruction of the Musculoskeletal System. (Barcelona, 2016)

– Alpe Foundation Award of Excellence for Achondroplasia (2014).

Persistent and Stable Growth Promoting Effects of Vosoritide in Children With Achondroplasia for up to 2 Years: Results From the Ongoing Phase 3 Extension Study. Ginebreda I, May 2021

Articles Once-daily, subcutaneous vosoritide therapy in children with achondroplasia: a randomised, double-blind, phase 3, placebo-controlled, multicentre trial. Ginebreda I, Sep 2020

SAT-LB18 A Randomized Controlled Trial of Vosoritide in Children With Achondroplasia. Ginebreda I, May 2020

Once-daily, subcutaneous vosoritide therapy in children with achondroplasia: a randomised, double-blind, phase 3, placebo-controlled, multicentre trial. Ginebreda I. Lancet. 2020 Sep

Lenghthening of the lower limbs and correction of lumbar hyperlordosis in achondroplasia. Human Achondroplasia. Ed. Plenum Publishing Corporation. Nov. 1988.

Lenghthening of lower limbs and correction of lumbar hyperlordosis in acondroplasia. Clinical orthopaedics. 1990. VOL, 250. 143-149. Vilarrubias Guillamet, J.M.; Ginebreda, Martí, I.; Jimeno Torres, E.

Surgical technique and outcomes for bilateral humeral lengthening for achondroplasia: 26-year experience. Ginebreda I. Musculoskelet Surg. 2019 Dec.


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    ICATME – Hospital Universitario Dexeus

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