The Intramedullary Skeletal Kinetic Distractor ISKD operates very similar to the fitbone method. Both are internal devices placed inside the bone being lengthened. The difference between the ISKD and the fitbone is how the lengthening of the device is done.
The ISKD involves the patient manually rotating the rod inside their leg to increase the distraction. This is done by turning the limb, whether at the knee or at the ankle, by a twisting motion until one hears the “click”. The rotation is monitored by a magnetic sensor that tracks the amount of rotation every day. While the possible issue of over extending the bone is removed, the other issue of bone refusing too quickly can occur.
The Fitbone method instead of letting the patient turn allows for the remote control increase of the rod. The receiver is in the leg while the patient controls is a radio frequency device transmitter.
From the Wikipedia article on Distraction Osteogenesis HERE…
Intramedullary skeletal kinetic distractor
In 2001, the “Intramedullary skeletal kinetic distractor” (ISKD) was introduced, allowing lengthening to take place internally, thereby drastically reducing the risk of infections and scarring. The ISKD device was designed by Dr. J. Dean Cole, MD of Orlando, Florida.
With ISKD, a telescopic rod that can be gradually extended by knee or ankle rotations is implanted into the bone. Lengthening is monitored by a hand-held external magnetic sensor that tracks the rotation of an internal magnet on a daily basis.
ISKD requires a physical leg movement to “click” the device into lengthening. In this method, there is no risk of accidentally over-stretching the bone due to the lengthener being preset to the desired fully extended length. However, there is a risk of growing the bone too quickly. Bone growth is monitored by measuring changes in the magnetic field of an embedded magnet in the system. The poles of the magnet change as the device grows. However, if the motion of the leg makes the device grow too quickly, and the magnet switches poles twice between measurements, then that growth is not recorded. This leads to overly rapid growth which can cause a number of issues such as nerve damage or causing breaks in the bone.
While there is some pain associated with the immediate post-op lengthening, the initial lengthening procedure is not to begin until one week after surgery. Furthermore, there is no noticeable “click” to the patient as there is less than nine degrees of rotation of the two bone segments in relation to one another.
Regularly used at a handful of medical centers mostly in the United States, only several dozens of ISKD devices are implanted each year. An improved version is currently being developed by its manufacturer (Orthofix).
From the Betz Institute website HERE
ISKD (Intramedullary Skeletal Kinetic Distractor) is an internal distraction device activated by polar movements through a small rotation of the bone segment being lengthened.
The ISKD measures the rate of distraction by a hand held monitor that is placed on the distraction area to record polar movements. The rate of distraction can be difficult to control due to the small degree of rotation required for lengthening.
The ISKD does not allow full weight bearing so patients are required to use a wheelchair during the entire lengthening phase.
The ISKD is used in special medical situations at the Betz Institute and allows for 8cm. (3 inch) gain in one bone segment.
From the Rubin Institute Of Advanced Orthopedics Website HERE…
The ISKD (Intramedullary Skeletal Kinetic Distractor) is an internal rod that is inserted inside the bone (bone marrow) for lengthening. You can find information on the ISKD, including pictures, brochures, and video clips, at the manufacturer’s website: http://www.orthofix.com
The device has two telescoping pieces that “unwind” to lengthen. This process is controlled by the patient’s leg movement. The rotational movement of the two pieces of the bone against each other causes the lengthening to occur. Inside the rod is a small magnet that rotates as the device lengthens. Other than x-ray, the only way to tell that lengthening has occurred is by using a monitoring device to track the magnet.
Things you should know about getting an ISKD at the International Center for Limb Lengthening:
- You must have a preoperative visit at our office a week or two before your surgery so that you can learn how the ISKD works and how to use the monitor. You will need to begin the monitoring process the day after surgery. Even if the patient is a child, they must participate in the learning process.
- You must have another person available to assist you with some of the lengthening exercises.
- You must return to our office approximately 1 week after surgery so that we can check your wound and you can learn how to begin the lengthening process. At that time, you will be shown some exercises that cause the rod to lengthen. Your helper must accompany you on this visit.
- You need to be prepared to stay overnight after that first follow-up visit in case there are any problems getting the lengthening to occur. Some people require an epidural anesthetic during the first few days of lengthening. If this is necessary, you will have to stay in the Baltimore area (not in the hospital) so that you can return every day for the next few days until you and your helper can demonstrate that you are able to lengthen the ISKD on your own. If you do not have a problem lengthening, you may leave after the visit.
- You will need to return to our office every 2 weeks during the lengthening process. You may need to return more frequently if you are having a problem controlling or monitoring the rate of lengthening.
- You will need to use the monitor frequently during the day. You may need to measure as often as every hour. You will need to keep the monitor with you at all times, including work or school.
- If the ISKD lengthens too quickly, it may be necessary for you to wear an external brace to help control any unintentional movements that you might make. You may be required to have the brace measured and manufactured prior to your surgery. Lengthening too quickly might cause nerve pain and poor bone formation.
- If the device lengthens too slowly, you risk having the bone heal prematurely. It might be necessary for your helper to manipulate your leg more vigorously in order to accomplish the movements needed to move the bone pieces enough to cause lengthening. This may be a painful process.
- You will be allowed to bear a maximum of 50 pounds of weight on the leg with the ISKD. This means that if you are having an ISKD inserted into both legs, you must use a wheelchair.
- You may not be allowed to drive for at least the first few weeks after surgery. You will need to get approval to drive from your surgeon. You should also check with your insurance company and department of motor vehicles to make sure you would be covered in the event of an accident.
- You will need to go to physical therapy; this is usually every day Monday through Friday.
- You may need to relocate to Baltimore during the lengthening phase; please discuss this with your surgeon.
- It is not as easy to control the lengthening process with the ISKD as it is with an external device. People who value control or who do not deal well with unpredictability may not be comfortable with the ISKD.