Lengthening Using an Motorized Nail

Motorized nails provide a great advancement of technology for limb lengthening surgery. Previously, the only way to gradually lengthen bones was with an external fixator.  A motorized nail is implanted within a bone, and the bone is carefully ‘cut’ at a certain point. The nail extends, and slowly moves the two bits of bone apart, slowly enough that new bone grows in the middle, so that the bone eventually heals and is longer than when it started.

The nail itself is ‘telescopic’, with a small motor inside that extends it. Think of an old-fashioned extendible car aerial, or extendable legs on a camera tripod, or even a telescope itself!

Because bone has to be lengthened very gradually (around 1 mm per day), the nail is only extended in very small increments at a time. This is achieved by placing an external ‘transceiver’ on the leg. This transceiver them transmits either a magnetic pulse or radio-frequency signal to the motor inside the nail (inside the leg).  This technology works very well, but it is very important that the transceiver is placed on the leg correctly, and used in accordance with the plan that is provided.

The advantage of using a motorized nail compared to a frame, is that there are no wires or pins protruding through the skin, which can reduce discomfort and scarring.

Does lengthening with a motorized nail hurt ?

There will be pain following surgery like many operations. After this, there will likely be some aching as the muscles, nerves, and bones are slowly lengthened. We have found that most children do not need any pain medications after a few weeks.

Do I need to wear a cast or a splint?

Muscles and tendons are also being stretched as a limb is lengthened. This means that joints like the ankle, or the knee, can become ‘stiff’ or not straighten fully. For this reason, depending on your situation, the LR team may also prescribe a brace or splint or cast to be worn. Instructions will be provided regarding how this is to be worn, and whether it can be taken off for movement of physiotherapy. 

Can I walk with the motorized nail?

Initially, most patients are only permitted to bear 10 kg of weight through the limb, and hence will need to use crutches or a frame to walk. Once the lengthening is complete and the bone is becoming ‘stronger’, the amount of weight allowed is increased. Some walking (within the permitted weight limit) is important, as it actually stimulates the bone to grow.

Moving your joints and completing physiotherapy is important while your limb is being lengthened, and your physiotherapist will instruct you in exercises that are within your weight bearing limit.

Can I shower or take a bath ?

Yes, once the initial surgical wounds are healed, usually after 10 – 14 days. However, the LR team will have drawn an arrow, or cross, on your leg, with a marking pen. This shows where the external transceiver needs to be placed, to activate the nail. As this ‘washes off’, it is important to keep re-drawing it in the same position, and you will be provided with a special pen for this purpose.

If the arrow on your leg washes off, please contact the LR team. Placing the transceiver even a few centimetres away from the marked location, may mean that the lengthening is ineffective.

Can I go back to school?

Yes! The Limb Reconstruction Team advocates for our patients to get back to school as soon as appropriate. A gradual return is commenced after discussion with the family and the school.

How do use the transceiver to activate the nail?

Prior to discharge from hospital, you will be provided with the transceiver, which is in a large box. You will be taught by one of the LR team, how to use the transceiver correctly.  A “plan” will be provided for you, telling you when to perform the lengthenings.

The transceiver has some inbuilt settings which are set by the LR team, to prevent you accidentally doing too much lengthening. If the transceiver malfunctions, or shows an unexpected message on the screen, please contact the LR team.

How many X-rays will be needed ?

X-rays are taken during the operation. After this, appointments will be made at one or two week intervals, and an x-ray is required each time. Each of these X-rays allows us to se  

Once the correction is complete, the interval between x-rays will be extended to between 4 and 6 weeks.

What can go wrong?

Lengthening a limb using a motorized nail is an advanced technique. It requires careful attention to following the prescribed plan, as well as regular review by the LR team. Sometimes, the lengthening goal may not be fully reached.

Lengthening relies on your body’s ability to heal the bone. If new bone is not growing on the x-rays, lengthening must be slowed down, or stopped all together. Conversely, if the bone grows too quickly or lengthening sessions are missed (including if the transceiver is used incorrectly), the bone may heal solidly and prevent further lengthening.

When lengthening a bone, the muscles and tendons must also stretch. This means that regular exercises and stretches will be prescribed. If muscles start to become tight, or joints start to become stiff, lengthening may need to be slowed down or stopped entirely.

When should I contact the LR team ?

• If there is an increase in pain of the affected limb.
• If there is any redness, swelling or discharge around the surgical incisions.
• If there is a fever that can't be explained by a cold, ear infection or other illness.
• If the transceiver device displays an unusual message or error message.

When can the motorized nail be removed?

The bone must be fully healed. Once the bone is sufficiently healed, usually 4-6 weeks after the lengthening has been completed, you will be allowed to bear weight on the limb. The motorized nail is usually removed a year or so after initial surgery.