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.
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
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.
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.
In gradual lengthening, the surgeon attaches a
After the bone is lengthened, it must heal in the
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
- 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
lengthening. 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
Another new way to gradually lengthen limbs uses a
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.
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
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.
Developed by the
Limb Lengthening and Reconstruction Society