How do my patients make the ISKD lengthen?
Patients cause lengthening anytime they create a slight internal/external rotation on their ISKD (about 9 degrees of rotation are required). These motions can occur naturally during daily activities, or can be intentionally produced. Preliminary data suggests that about half of the total distraction is achieved without intentional effort, but individual results vary. The patients must check their progress during the day using their handheld monitor to ensure that they are getting the prescribed amount of lengthening per day.
How much motion does it take to cause lengthening?
In total, about 60 cycles of internal/external rotation will cause 1 mm of distraction. However, these cycles are spread out during the day, and some patients report slight lengthening even while sleeping.
Can my patients get too much lengthening in a day?
Yes. Patients use their handheld monitor to check their progress during the day. This ensures that they are getting the prescribed amount of lengthening. The monitor provides feedback and allows the patients to gage how much activity they can exert. Thus too much or too little lengthening can be avoided.
How does the handheld monitor work with the ISKD?
The ISKD contains a very small but powerful magnet hermetically sealed within the shaft of the threaded rod that drives the distraction motion. The magnet rotates slightly every time the ISKD lengthens even a small amount. Like all magnets, the ISKD magnet has both a north pole and a south pole. The handheld monitor reads the magnetic field created by these poles, and every time the pole changes (e.g. from north to south) this equals .375 mm of lengthening. The patient simply holds their monitor directly over the magnet and presses a single button to take a measurement. The monitor contains software that calculates the amount of distraction achieved and stores in memory all the readings taken by that patient. Each time the patient uses their monitor, they know how much distraction they have achieved on that particular day, and in addition, how much total distraction they have achieved since the ISKD was first implanted.
Do patients weight bear freely with ISKD?
No. Patients must use a walker, crutch or cane to ambulate. Only about 50 pounds of weight may be placed on the leg during both the distraction and consolidation phases of the lengthening.
