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Treatment · General Orthopedics

Leg Lengthening with an ISKD Nail | Doctors & Treatment Information

Sabine SchneiderEditor-in-ChiefSabine Schneider

The new method of leg lengthening using the ISKD nail avoids the problems and complications associated with a fixed frame. These include: painful infections at the entry site, prolonged wear, and psychological stress. The advantages of treatment with the ISKD nail include improved joint mobility and faster rehabilitation.

Here you can find more information and specialists.

Methods for Leg Lengthening

Leg length discrepancies can be congenital or result from injury, infection, or other acquired conditions. Leg length discrepancies of more than 2 cm often lead to symptoms: The unequal leg lengths cause the pelvis to tilt. This results in curvature of the spine. This results in pain and premature wear and tear of the hips and lower spine.

While shoe lifts or custom-made shoes are available to compensate for the shortening, they are not a helpful solution for most patients.
 
Callus distraction is a procedure for the artificial lengthening of bones. Doctors perform it in cases of limb shortening or axial misalignment, as well as for long-segment bone defects. Even long-segment lengthening of the upper or lower leg bones is possible.

Leg Lengthening with an External Fixator

The following complications frequently occur with the conventional treatment using an external fixator:
  • Wires can cause painful infections at the entry points, which can also affect bones and joints. Because the wires pierce the skin, muscles, and tendons, joint mobility is significantly restricted.
  • After removal of the external fixator, the newly formed callus tissue may bend, shorten, or even fracture.
  • The external fixator must be worn for a relatively long period, ranging from 6 to 12 months. This delays rehabilitation and a return to work.
  • Experience has shown that the bulky external fixator places a considerable physical and psychological burden on the patient. For this reason, experts have been researching for decades how leg lengthening can be achieved using an internal implant.
Leg Lengthening with an External FixatorThe external fixator is a method for correcting leg length discrepancies @ Olga Alperovich /AdobeStock

Leg Lengthening with the ISKD Nail

The Intramedullary Skeletal Kinetic Distractor (ISKD nail) is a modern lengthening nail that avoids the complications associated with the external fixator. It lengthens mechanically through rotational movements of at least 3° in the area of the severed, lengthening bone.

The ISKD nail consists of a narrow lower section and a wider upper section. These sections can slide into one another and are connected via ratchet mechanisms. When rotational movements of 3° or more occur between the upper and lower sections of the nail, the ratchet mechanism is activated. This causes the nail to lengthen slightly.

The mechanism inside the nail works such that when the patient rotates it slightly, the nail automatically lengthens. The patient must rotate the nail 160 times by 3 degrees to lengthen it by 1 millimeter.
 
This rotation occurs even when the patient places a little weight on or moves the leg after surgery. There is a magnet inside the nail. This magnet changes direction when the patient rotates the nail. A small monitor measures this process. The monitor displays the daily and total lengthening distance.
 
If the lengthening is insufficient, the patient can move the leg more to achieve the desired lengthening distance.
 
This also works the other way around. If the leg is lengthening too much, the patient should temporarily reduce the weight-bearing and movement.
 
Adult patients can achieve upper or lower leg lengthening of between 2 and 8 cm using the ISKD nail.

Examinations Before Leg Lengthening

A thorough clinical and radiological examination is necessary before surgery. Doctors analyze leg length discrepancies and possible misalignments.
 
Using small wooden boards, the doctor simulates a leg lengthening. He or she determines whether the misalignment at the hip joints and the spine can be corrected.
 
In addition, a clinical examination of the range of motion and stability of the joints is performed.
 
Using X-rays of the leg axes, the doctor identifies axial deviations and measures the leg length discrepancy with millimeter precision using computed tomography.
X-ray of a legRegular X-rays are an essential part of the treatment @ H_Ko /AdobeStock

The duration of leg lengthening using an ISKD nail

The surgery takes 2 to 3 hours. The following day, the patient is provided with forearm crutches so that they can begin to bear some weight on the operated leg.
 
The hospital stay lasts approximately 7 days. After being discharged from the hospital, the patient should attend regular follow-up appointments. During these follow-ups, doctors monitor the extent of the lengthening and joint mobility.
 
The leg is lengthened by 1 mm per day. The healing of the separated bone typically takes 2 to 3 days per mm.
 
For a leg lengthening of 4 cm, a bone healing period of about 4 to 5 months can therefore be expected. Full weight-bearing is possible just a few weeks after the lengthening is complete.

Medications During Treatment

Doctors usually perform the procedure under spinal anesthesia. A pain catheter is recommended for the first few days after surgery. At the patient’s request, doctors can also perform the procedure under general anesthesia.
 
During bone lengthening, the surrounding soft tissues (muscles, ligaments, and tendons) are stretched. This tension in the soft tissues can be painful. Therefore, patients are usually given pain medication.
 
The patient begins performing the rotational movements required for lengthening shortly after surgery. If these are insufficient, targeted rotational movements are performed to activate the lengthening mechanism. The patient receives pain medication for this procedure.
 
In addition, the doctor routinely administers antithrombotic injections into the subcutaneous fatty tissue.

Postoperative Care

Shortly after the surgery, the patient receives physical therapy instructions to help them mobilize the leg quickly. A motion splint and forearm supports assist with this. The patient also receives a manual explaining how the nail works.
 
An external monitor tracks the nail’s extension. If the extension is insufficient, the patient can assist the process with targeted rotational movements. If the extension is excessive, the patient should temporarily reduce the load on the leg.
 
After discharge from the hospital, outpatient follow-up visits are initially scheduled every 1 to 2 weeks. Once the desired length of extension has been reached and initial bone formation is visible on X-rays, the patient transitions to full weight-bearing.
 
Through physical therapy exercises, the patient also works on the mobility of the adjacent joints. The timing of a return to work depends on the patient’s occupation. Sedentary activities are possible just a few weeks after the lengthening is complete.

Contraindications for Leg Lengthening Using an ISKD Nail

The nail is not suitable for children and adolescents whose growth plates are still open. The nail would damage the growth plates.
 
In some patients, a bone marrow cavity that is too narrow or deformed makes it difficult to insert a straight lengthening nail.
 
For patients who have had a bone infection in the past, doctors carefully evaluate whether to proceed with treatment using a lengthening nail.

Advantages of leg lengthening using a lengthening nail

Since the nail is located entirely within the bone, the problems and complications associated with an external fixator are avoided.
 
These include:
  • Infections
  • Pain at the entry points of the wires
  • Severe limitations of movement
  • Bone deformities
  • Delayed rehabilitation
  • Low comfort during treatment

Risks of leg lengthening with an ISKD nail

Leg lengthening should only be performed by experienced centers. Compared to an external fixator, complications are significantly lower.

However, the general risks of surgery still apply:
  • Infections
  • Injuries to nerves and blood vessels
  • Formation and displacement of a blood clot (thrombosis/embolism)
The specific surgical risks associated with treatment using the ISKD lengthening nail include:
  • Premature bone healing (requiring re-cutting of the bone)
  • Excessively rapid lengthening (treatment by increasing off-loading; if necessary, temporary application of a unilateral external fixator)
  • Delayed or absent callus formation (treatment by grafting autologous cancellous bone from the iliac crest)
  • Joint contractures (intensive physical therapy, soft tissue surgery if necessary)
  • Axial deformity, leg length discrepancy (surgical correction if necessary)

Questions about leg lengthening using an ISKD lengthening nail

When does the lengthening nail stop growing?

Before implantation, doctors adjust the lengthening nail individually to the desired lengthening distance. Excessive, unintended lengthening is not possible.

Can I play sports again with my lengthened leg?

As soon as the newly formed bone is fully consolidated, you can participate in sports without any concerns.

Is another surgery needed to remove the lengthening nail?

Removal of the nail is not necessary. Normally, only a single surgical procedure is required.

Sabine Schneider

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Sabine Schneider

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