Oncology
 Expandable Prosthetics  

Bone cancers, including osteosarcoma, were once the frequent cause of amputations in children. Surgery to remove the affected bone is usually necessary to treat bone cancers and in the past, many patients would end up without part of an arm or a leg. However, new technologies have made limb salvage surgery the preferred choice for doctors and patients.

One problem in the past is that children´s bones are constantly growing. Artificial devices that were installed after surgery would later lead to limb-length discrepancy. Patients would then be subject to multiple surgeries to lengthen the existing device.

Custom, modular endoprostheses were developed by surgeons and engineers to allow for limb lengthening with minimal revision surgery. These devices have been around since the late 1970s with varying degrees of success. Recently, new developments have been more promising and even allow for lengthening without any type of surgical procedure. One of the latest in adjustable prosthesis development is the noninvasive, expandable oncology endoprosthesis. It was developed by a French engineer and was first used in the United States at the Institute for Limb Preservation in Denver in the late 1990s.

This endoprosthesis is made of titanium and plastic, and consists of two tubes with a spring mechanism, which is compressed by a locking device. It weighs about the same as the patient´s bone and ranges in size depending on the patient. When it comes time for the implant to grow with the patient, a magnetic field is delivered outside of the body, allowing the device to expand.

Once the electromagnetic field is removed the expansion of the device is halted. These growth spurts can continue for as long as they are needed and last about 20 seconds.

Throughout a child's normal growth cycle, a conventional modular prosthetic implant may require 5-6 surgeries to accommodate the child´s growth. The new technology of the expandable prosthesis can greatly reduce this number of surgeries.

While this technology is still new, it is making living with an artificial device much easier. It is not known how long these implants will last but researchers say that they aren´t designed to last a lifetime. As with all implants there is still a risk of infection with this device.

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