Nurse attending to patient recovering from limb lengthening surgery at Texas Scottish Rite Hospital for Children

What Is Limb Lengthening?

Limb lengthening is a surgical procedure used to lengthen bones or replace segments of missing bone in the upper and lower extremities. Limb lengthening can be performed in two different ways, depending on the cause of the limb length difference and any associated deformity of the bone. One approach is to attach an external frame to the affected limb. The frame supports the limb and allows gradual lengthening of the bone through a fracture created during surgery. Another approach is to insert a rod into the bone that will also gradually lengthen the bone after creating a fracture during surgery. Each technique has advantages and disadvantages that your physician will discuss with you. More than one stage of treatment may be required for extensive limb lengthening. 

Limb length discrepancies, also known as limb length differences, can be present at birth or may develop during childhood. Certain congenital anomalies, severe bone infections, traumatic injuries and neurological disorders can result in limb length discrepancies. 

A doctor can determine the severity of a limb length discrepancy by a simple clinical exam or by X-rays of the extremities. This evaluation is often repeated, sometimes every six months, to monitor the limb length difference in growing children. 

The decision to treat a limb length discrepancy depends on the amount of difference there will be when the child stops growing. Not all discrepancies need to be treated. For those that do, treatment type is determined by the amount of difference expected at maturity. For lower extremity differences, the following treatments are generally followed:

  • 0-2 cm (< 1 inch): Treatment might not be necessary, but your doctor may suggest a shoe lift, most commonly placed inside the shoe. 
  • 2-5 cm (1-2 inches): A small surgery may be done close to skeletal maturity to slow the growth of the longer leg. This allows the shorter leg to catch up in length.
  • 5-15 cm (2-6 inches): Surgical options include:
    • Shortening the longer leg: Once the child is finished growing, surgery is done to remove a section of bone from the longer side to make the legs more even.
    • Lengthening the shorter leg: Our Center for Excellence in Limb Lengthening employs two primary approaches to limb lengthening: 
      • The first method is the PRECICE® intramedullary rod. Once the device is surgically implanted inside the bone, patients benefit from its groundbreaking magnetic, noninvasive adjustment capability to lengthen the bone. 
      • The second method involves putting a TRUE/LOK™ External Fixation System on the leg. Scottish Rite for Children researchers developed the TRUE/LOK™ system in 1993 and have recently released the state-of-the-art TRUE/LOK™ HEX six-strut hexapod external fixator. This system allows simultaneous correction of length differences with associated deformity of the bone. 
      • For both methods, the bone is lengthened gradually through a surgically created fracture, allowing new bone to form in the gap. Both methods have proven to be very successful. However, regardless of the method, it takes many months to lengthen the bone and allow it to fully heal, and requires a commitment from the patient and family to complete the treatment.

It depends on the severity of the expected difference when the child becomes skeletally mature. 

For lower extremity differences, the following treatments are generally followed:
  • 0-2 cm (< 1 inch): Treatment might not be necessary, but your doctor may suggest a shoe lift, most commonly placed inside the shoe. 
  • 2-5 cm (1-2 inches): A small surgery may be done close to skeletal maturity to slow the growth of the longer leg. This allows the shorter leg to catch up in length.
  • 5-15 cm (2-6 inches): Lengthening of the short leg, often combined with slowing of the growth of the long leg.
Advancements in the treatment of limb length differences continue to be made through Scottish Rite for Children's Center for Excellence in Limb Lengthening.

There are many factors involved in determining which device is appropriate for you. In general, lengthening the humerus (arm), femur (thigh) or tibia (leg) can be performed with a rod that is inserted into the bone if there is no associated deformity of the bone. After surgically creating a fracture in the bone, the rod can be gradually lengthened magnetically, which will also gradually lengthen the bone. 

If there is deformity of the bone, doctors at Scottish Rite for Children use the TRUE/LOK™ or TRUE/LOK™ HEX External Fixation System, which is made up of two or more rings attached to your limb. After the rings are connected, a fracture is surgically created in the bone. Special rods are then attached to the rings that are designed to be lengthened. After surgery, the doctor will show you how to turn the rods to gradually lengthen the bone. This is repeated until the desired length is reached. Because our bodies are programmed to automatically heal broken bone, the gap in the bone created by the lengthening slowly fills in as you turn the frame to lengthen the limb. The frame is worn until the bone is healed.

Because the bone is lengthened gradually, your muscles, skin, nerves and blood vessels have time to grow along with the bone. However, sometimes the muscles won’t lengthen as much as the bone will, and this will limit the amount of lengthening that can be achieved.

You will be under anesthesia when the doctor implants the rod or attaches the external fixator, so you won’t feel pain during the surgery. You may experience some soreness as the bone lengthens, regardless of the technique used. In addition, wearing the frame when not lengthening the bone can be uncomfortable. Your doctor will give you medicine to help manage the pain, and our psychologists can teach you ways to cope with the discomfort.

Regardless of the technique used to lengthen a bone, the process of lengthening the bone and the healing of the bone can take six to nine months. The exact length of time depends on how much lengthening is needed. Lengthening a bone rarely takes more than a couple of months, and the rest of the time is spent allowing the bone to heal.

The speed at which the bone is lengthened is dependent on multiple factors. In general, you will be asked to activate the internal rod or turn the rods of the external fixator two to four times per day, which lengthens the bone by about one-half to one millimeter per day. Your doctor and nurse will give you more specific instructions on how to lengthen your internal rod or external fixator and when to begin the process.

Yes. Your doctor will tell you when you may return to school. It is important to keep as normal a daily routine as possible.

There is no restriction to what you can wear. If you have an external fixator on your leg, it is recommended to wear shorts, skirts or loose pants that can fit comfortably over the frame.

Working on range of motion and strengthening exercises after surgery is the most important thing you will be asked to do. Scottish Rite for Children's physical therapists will teach you an exercise program that you will be required to perform every day. Some patients need to work with an outside physical therapist as well. Your doctor and our physical therapists will determine this need.

If you will be wearing an external fixator, you are allowed to bear full weight on your extremity and can still participate in some athletic activities. Wearing the frame will restrict your movement, and you may not be comfortable enough to bear full weight for several weeks after placement. Scottish Rite for Children's doctors, physical therapists and therapeutic recreation specialists will help you continue to do as many of your favorite activities as possible. Swimming is a good way to stay fit without putting too much strain on the limb, but remember to swim only in chlorinated or saltwater pools. Do not swim in lakes or ponds.

If you are lengthening the femur (thigh) or tibia (leg) with an intramedullary rod, you will not be allowed to bear full weight on that lower extremity until the lengthening is completed and the bone is almost fully healed. The doctors will tell you when it is safe to walk with full weight on that leg.

Typically, you will need to visit Scottish Rite once every week while you are lengthening the internal rod or the external fixator. After the bone is lengthened, appointments are usually scheduled once per month until the bone is completely healed.

It is removed in the operating room while you are asleep. Some patients need a cast or brace after removal of the external fixator. Your doctor will let you know if you need a brace or cast. 

The manufacturer of the rod recommends removal of the rod. Your doctor will recommend the best time to do this. Generally, it is removed 6-12 months after the bone is completely healed.

Scottish Rite for Children began its limb lengthening research program in 1992. The Center for Excellence in Limb Lengthening employs a unique multidisciplinary team approach including collaboration between our orthopedic surgeons alongside nurses, psychologists, physical and occupational therapists, and researchers of varying backgrounds and expertise. Learn more about our current research studies.

In 1993, by modifying Ilizarov’s original external fixator, Scottish Rite for Children's research team developed and patented a new device called the TRUE/LOK™ External Fixation System (TrueLok). The device was created to treat deformities and extremity trauma and to lengthen limbs with a simpler but more adaptable external fixator.

In 2012, a three-dimensional bone segment adjustment module called TL-HEX enhanced the TrueLok. As with other hexapod-based systems, TL-HEX required complex, three-dimensional software. TL-HEX Software was developed in collaboration with Orthofix International (USA) and New Orthopedic Instruments (Russia).

Learn more about our innovations in treatment methods. 

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