Limb Lengthening


Limb lengthening is a surgical procedure used to treat a
limb-length discrepancy (LLD) of the arm or leg. The goal is to
achieve equal length with the corresponding opposite limb. LLD is
the difference between the lengths of the upper arms and/or lower
arms, or a difference between the lengths of the thighs and/or lower
legs. In the past, surgeons rarely lengthened bones. That’s because
complications were common, the additional length gained was small,
and the newly formed bone was weak. Today, advanced surgical
techniques have reduced complications significantly. Patients are
able to return to their daily activities soon after surgery.

LLD may be due to normal variation that occurs between the two
sides of the body. Or it may be due to other causes. Some
differences are so common that they are considered normal and need
no treatment. For example, a study of 600 military recruits found
that 32 percent had a 5 mm to 15 mm (approximately one fifth inch to
three fifths inch) difference between the lengths of their two lower
extremities; this is a normal variation. Greater differences may
need treatment if the discrepancy affects a patient’s well being and
quality of life.

A physician can measure LLD during a physical examination. He or
she may measure the difference between the:

  • Levels of the soles of the feet

  • Levels of each side of the pelvis when standing

  • Lengths from the hips to the ankles

If a more precise measurement is needed, the doctor may request
an X-ray to measure the length of the bones. In growing children, a
physician may repeat the physical examination and X-ray every six
months to one year. This can determine if the LLD has increased or
stayed the same.

Risk Factors/Prevention

There are many possible causes of LLD:

  • Previous injury: A previously broken bone may cause LLD
    if it healed in a shortened position. This can happen if the bone
    was broken in many pieces (comminuted) or if the skin and muscle
    tissue around the bone were severely injured and the bone was
    exposed (open fracture). In children, broken bones may grow faster
    for several years after healing. This causes the injured bone to
    become longer. A break in a child’s bone through the growth center
    (located near the ends of the bone) can cause slower growth. This
    results in a shorter extremity.

  • Bone infection: Bone infections in growing children,
    especially infants, may cause significant LLD.

  • Bone diseases (dysplasias): These include
    neurofibromatosis, multiple hereditary exostoses and Ollier

  • Inflammation: Juvenile rheumatoid arthritis is one
    example of inflammation of joints during growth that can cause
    unequal extremity length. Joint degeneration in adults
    (osteoarthritis) rarely causes significant LLD.

  • Neurological conditions: Neurological conditions during
    childhood, such as cerebral palsy, polio and obstetrical brachial
    plexus palsy, may affect the growth of an arm or leg and result in

Sometimes conditions are present at birth, but the LLD may not be
detectable. As the child grows, the LLD increases and becomes more
noticeable. Examples include:

  • Hemimelia: Underdevelopment of the inner or outer side
    of the leg is called hemimelia. One of the two bones between the
    knee and ankle (tibia or fibula) is abnormally short. There may
    also be foot and knee abnormalities.

  • Hemihypertrophy: Stimulation of growth of one side of
    the body from an unknown cause is called hemihypertrophy. It is a
    rare condition. Hemihypertrophy causes over-growth of both the arm
    and leg on the same side of the body. There also may be
    differences between the two sides of the face.

Sometimes no cause for an unequal extremity can be determined
using current diagnostic methods. This is called idiopathic.


The effects of LLD vary from patient to patient. Symptoms depend
upon the cause of the discrepancy and the size of the difference.

  • Differences of 3.5 percent to 4 percent of the total length of
    the lower extremity (4 cm or 1 2/3 inch in an average adult),
    including the thigh, lower leg and foot, may cause noticeable
    abnormalities while walking. The patient may need considerably
    more effort to walk.

  • Differences between the lengths of the upper extremities may
    cause few problems, unless the difference is so great that it
    becomes difficult to hold objects or perform chores with both

A LLD may be detected on a screening examination for curvature of
the spine (scoliosis). However, LLD does not cause scoliosis. There
is controversy about the effect of LLD on the spine. Some studies
show people with LLD have a greater incidence of low back pain and
are at increased risk for injury; other studies refute this

Treatment Options

The patient and physician should discuss whether treatment is
necessary. An adult with no other deformity may not need treatment
for a minor LLD. Because the risks may outweigh the benefits,
surgical treatment to equalize leg lengths is usually not
recommended if the discrepancy is less than one inch. For small
differences, the physician may recommend a shoe lift. This is fitted
to the shoe. It can often improve walking and running. It can also
relieve back pain caused by LLD. Shoe lifts are inexpensive. They
can be removed if they are not effective. They add weight and
stiffness to the shoe.

Treatment Options: Surgical


In some cases, the longer extremity can be shortened with
surgery. However, a major shortening may cause weakening of the
muscles of the extremity. In growing children, lower extremities can
also be equalized by a surgical procedure that stops growth at one
or two sites of the longer extremity. It leaves the remaining growth
undisturbed. Using charts or formulas, a physician calculates how
much equalization can be reached by surgically stopping one or more
growth centers. This procedure is performed under X-ray control. The
surgeon uses a very small incision in the knee area.

The procedure will not cause immediate correction in length.
Instead, the LLD gradually decreases as the opposite extremity
continues to grow and “catch up.” The timing of the procedure is
critical; the goal is to reach equal lengths of the extremity at
skeletal maturity. This usually happens by the mid- or late teens.
Disadvantages include the possibility of slight over-correction or
slight under-correction of the LLD. The patient’s adult height will
be somewhat less than if the shorter extremity had been lengthened.
Correction of a significant LLD by this method may make a patient’s
body look disproportionate because of the shorter legs.

Surgical lengthening of the shorter arm or leg is another
treatment option. The process may be immediate or gradual.

Immediate lengthening

In immediate lengthening, the desired increase in the bone’s
length is attained while the patient is under an anesthetic in the
operating room. When performing acute lengthening, the orthopaedic
surgeon makes a cut in the bone, slides it and maintains the length
and position with an internal device (i.e., screws or metal plates).
Or the surgeon may cut the bone, spread the two sections apart, and
insert a graft and internal metal devices to maintain the length.
Surrounding muscles, nerves and blood vessels do not tolerate a lot
of stretching. So acute lengthening can only achieve limited
increases. For example, forearm bones (radius or ulna) and foot
bones (metatarsals) are lengthened by this method when only a small
gain in length is needed.

Gradual lengthening

In gradual lengthening, the surgeon attaches a
scaffold-like frame (external fixator) to the bone with metal
pins, wires, or both (Figure 1). The bone is cracked through a
small incision; the bone then “rests” for a few days. The
patient wears the frame until the correction is achieved. The
frame creates tension when it is “distracted” by the patient
or family member who turns an affixed dial several times
daily. The surgeon determines the rate of turning by taking
X-rays every 10 to 14 days during office visits. Although this
lengthening process is often called “stretching,” the bone is
not stretched. Instead, the very small amount of tension that
the frame exerts on the bone stimulates the bone to grow. This
fills the gradually enlarging gap with new bone. The
surrounding muscles, nerves, skin and blood vessels also grow.
The maximum rate of lengthening in children is usually 1 mm
per day, or 1 inch per month. Lengthening may be slower in
adults. It may also be slower in a bone that was previously
injured or had surgery.

After the bone is lengthened, it must heal in the
lengthened position (consolidation phase). Then the frame is
removed. Under ideal conditions, the time “in the frame” is
approximately 2 1/2 months to 3 months per inch. This time
varies depending upon your age, general health, whether you
smoke, your participation in rehabilitation, etc. Some
activities may be more difficult when wearing a frame (i.e.,
getting in and out of a car). Most patients can easily return
to work, school or daily routines. When the surgeon determines
that bone strength is nearly normal again, the frame, pins,
and wires are removed. Gradual lengthening can achieve
significant gains in length if the process is repeated several
years later, or if it is performed at opposite ends of the
same bone at the same time. This “double level lengthening”
achieves lengthening rates greater than 1 mm per day.
Deformities, such as malunion following a broken bone, can
also be corrected while the bone is being lengthened.


Many patients ask about the amount of pain associated with limb
lengthening. There is some discomfort with any surgery. Pain
medicine is given as needed while the patient is in the hospital
(usually two days to three days). The surgeon will prescribe pain
medicine as needed when you leave the hospital. Little pain is
experienced once the patient is home and the lengthening process is
underway. If there is a sudden increase in pain, contact your
surgeon immediately. Pain may be a warning sign of a possible
complication and must be addressed quickly.

As with any surgical procedure, there are risks. See your surgeon
after the operation for scheduled office visits to minimize

  • The bone may heal too rapidly (premature consolidation)
    and need to be cracked again to continue the lengthening process.

  • The bone may heal too slowly (delayed union). This can
    require that you wear the fixator for extra time, use an external
    bone stimulator or undergo more surgery, such as insertion of a
    bone graft.

  • The pins or wire sites can become infected. If
    untreated, infection can spread to the bone. To minimize this
    risk, the surgeon will tell the patient how to very carefully
    clean the pins and wires.

  • Joint stiffness (contractures) may occur during
    . This is especially true for significant
    lengthenings. If joint stiffness happens, the lengthening may need
    to be stopped or further surgery may be needed. Participation in
    prescribed physical therapy and home exercises will minimize the
    chances of joint problems.

  • Fractures of the new bone may occur when the external
    fixator is removed. Initially, the new bone is not as strong as
    the original bone. If the bone breaks, the surgeon may apply a
    cast, reapply the fixator or restrict the patient’s physical

Research on the Horizon/What’s New?

A new way to lengthen the bones of the lower extremities
combines use of an external fixator and a metal rod inserted
into the canal of the bone (intramedullary nail). This
procedure is very similar to lengthening performed with an
external fixator; however, it decreases the risk of newly
lengthened bone bending or breaking following removal of the
external fixator. The patient spends less time “in the frame”
when the combined procedure is used. The main disadvantages
are prolonged use of crutches or a walker and the possible
risk of a severe bone infection.

Another new way to gradually lengthen limbs uses a
telescoping nail. In this surgery, an expanding metal rod is
inserted into the internal canal of the thighbone (femur) or
shin bone (tibia) (Figure 2). Then the surgeon makes a small
crack in the bone. During the next few weeks and months, the
length of the nail increases. This causes lengthening of the
surrounding bone. Movement of the leg activates the
lengthening components of the nail. An advantage of this
technique is that there is nothing worn outside the extremity.


A telescoping plate for gradual lengthening of the femur
(thighbone) is currently under development. The plate is attached to
the surface of the bone and a small crack is made in the bone.
Beginning several days after surgery, the bone is gradually
lengthened by frequent adjustments made with a small wrench through
a tiny hole in the skin.

Cosmetic lengthening

Some patients inquire about lengthening both legs to achieve
greater height. This process is called cosmetic lengthening. Because
of the possible complications, patient commitment and expense,
cosmetic lengthening is rare. Patients who are considering cosmetic
lengthening must consult an orthopaedic surgeon skilled in
performing these procedures. Carefully weigh the risks and benefits
of surgery.

If you have a limb length discrepancy, an orthopaedic surgeon
experienced in bone lengthening techniques can explain the treatment
options and their risks and benefits in more detail. You and your
surgeon can then decide what treatment, if any, is best for you.

December 2004

Developed by the
Limb Lengthening and Reconstruction Society

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Reviewed by members
of POSNA (Pediatric Orthopaedic Society of North America)