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Leg lengthening and shortening

Definition

Leg lengthening and shortening are types of surgery to treat some children who have legs of unequal lengths.

These procedures may:

• Lengthen an abnormally short leg
• Shorten an abnormally long leg
• Limit growth of a normal leg to allow a short leg to grow to a matching length

Alternative Names

Epiphysiodesis; Epiphyseal arrest; Correction of unequal bone length; Bone lengthening; Bone shortening; Femoral lengthening; Femoral shortening

Description

BONE LENGTHENING

This series of treatments involves several surgical procedures, a long recovery period, and a number of risks -- but it can add up to 6 inches of length to a leg.

While the child is under general anesthesia:

• The bone to be lengthened is cut.
• Metal pins or screws are inserted through the skin and into the bone. Pins are placed above and below the cut in the bone, and the surgical cut in the skin is stitched closed.
• A metal device (usually some sort of external frame) is attached to the pins in the bone. It will be used later to very slowly (over months) pull the cut bone apart. This creates a space between the ends of the cut bone that will fill in with new bone.

Later, when the leg has reached the desired length and has healed (usually after several months), another surgical procedure will be done to remove the pins.

BONE RESECTION OR REMOVAL

This is a complicated surgery that can produce a very precise degree of correction.

While the child is under general anesthesia:

• The bone to be shortened is cut and a section of bone is removed.
• The ends of the cut bone will be joined and a metal plate with screws or a nail down the center of the bone is placed across the bone incision to hold it in place during healing.

BONE GROWTH RESTRICTION

Bone growth takes place at the growth plates (physes) at each end of long bones.

While the child is under general anesthesia, the surgeons make a surgical cut over the growth plate at the end of the bone in the longer leg.

• The growth plate may be destroyed by scraping or drilling it (epiphysiodesis or physeal arrest) to stop further growth at that growth plate.
• Another method is to insert staples on each side of the bony growth plate. These can be removed when both legs are close to the same length.

REMOVAL OF IMPLANTED METAL DEVICES

Metal pins, screws, staples, or plates may be used to stabilize bone during healing. Most orthopedic surgeons prefer to wait several months to a year before removing any large metal implants. Removal of implanted devices requires another surgical procedure using general anesthesia.

Why the Procedure Is Performed

Leg lengthening is considered for large differences in leg length (more than 5 cm or 2 inches). Leg lengthening is more likely to be recommended:

• For children whose bones are still growing
• For patients who were short to begin with

Leg shortening or restricting is considered for smaller differences (less than 5 cm or 2 inches). Shortening a longer leg may be recommended for children whose bones are no longer growing.

Bone growth restriction is recommended for children whose bones are still growing. It is used to restrict the growth of a longer bone, while the shorter bone continues to grow to match its length. Proper timing of this treatment is important to ensure good results.

Medical illnesses that lead to severely unequal leg lengths include the following:

• Poliomyelitis and cerebral palsy
• Small, weak (atrophied) muscles or short, tight (spastic) muscles, which may cause deformities and prevent normal leg growth
• Hip diseases such as Legg-Perthes disease
• Previous injuries or bone fractures that may stimulate excessive bone growth
• Birth defects (congenital deformities) of bones, joints, muscles, tendons, or ligaments

Risks

Risks for any anesthesia include:

• Reactions to medications
• Problems breathing

Risks for any surgery include:

• Bleeding
• Infection

Additional risks include:

• Bone growth restriction (epiphysiodesis), which may cause short height
• Bone infection (osteomyelitis)
• Injury to blood vessels
• Poor bone healing
• Nerve damage

After the Procedure

After bone growth restriction:

• It is common for children to spend up to a week in the hospital. Sometimes a cast is placed on the leg for 3 to 4 weeks.
• Healing is complete in 8 to 12 weeks, at which time the child can restart full activities.

After bone shortening:

• It is common for children to spend 2 to 3 weeks in the hospital. Sometimes a cast is placed on the leg for 3 to 4 weeks.
• Muscle weakness is common, and muscle strengthening exercises are started soon after surgery.
• Crutches are used for 6 to 8 weeks.
• Some children take 6 to 12 weeks to regain normal knee control and function.
• A metal rod placed inside the bone is removed at 1 year.

After bone lengthening:

• The child will spend a week or longer in the hospital.
• Frequent visits to the doctor are needed to adjust the lengthening device. How long the lengthening devidce is used depends on the amount of lengthening needed. Physical therapy is needed to maintain normal range of motion.
• Special care of the pins or screws holding the device is needed to prevent infection.
• How long it takes the bone to heal depends on the amount of lengthening. Each centimeter of lengthening takes 36 days of healing.

Because the blood vessels, muscles, and skin are involved, careful and frequent checking of the skin color, temperature, and sensation of the foot and toes is important. This will help identify any damage to blood vessels, muscles, or nerves as early as possible.

Outlook (Prognosis)

Bone growth restriction (epiphysiodesis) is usually successful when it is performed at the correct time in the growth period. However, it may cause short stature.

Bone shortening may achieve more exact correction than bone restriction, but it requires a much longer recovery period.

Bone lengthening is completely successful only 40% of the time, and has a much higher rate of complications.

References

Beaty H. Congenital anomalies of the lower extremity. In: Canale ST, Beaty JH, eds. Campbell's Operative Orthopaedics. 11th ed. Philadelphia, Pa: Mosby Elsevier;2007:chap 26.

Hosalkar HS, Gholve PA, Spiegel DA. Leg-length discrepancy. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 675.