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Metal Detector To Find Troublesome Orthopedic Screws
- By Simon Harris
- Published September 8th, 2008
- Orthopedics
- Unrated
An eight-member team of Johns Hopkins biomedical engineering students have invented a metal detector to find the hidden orthopedic screws in patients' bodies in order to remove them. The device is inspired by the similar device that is used to find the lost coins in the sand. The detector emits a tone that rises in pitch when the surgeon moves closer to the metal screw. It also acts as a surgical tool to guide the removal of the hardware.
Orthopedic screws are used by orthopedic surgeons to hold the broken bone fragments together for proper healing. These are made of stainless steel or titanium alloy and are produced in different lengths. Their screw heads range from 3 to 7 millimeters in diameter. The screws need to be removed sometimes when they change their position from the original one and cause infection as well as pain. Sometimes it becomes very difficult to find those troublesome screws or hardware because of the sin and scar tissue, even with the help of X-ray. The small metal detector is designed in such a way that when it approaches the hardware, it steer the doctor's screwdriver into the right position for removal.
“When
orthopedic screws are difficult to find, removing them can require an expensive operation,” said Malcolm M. Lloyd, a physician and chief executive officer of Surgical Transformations. “Orthopedic surgeons told us it would be great to have a metal detector to locate these small, sometimes isolated screws. These surgeons felt that expensive, time-consuming and more invasive surgical procedures could be avoided if such a metal detection tool was readily available. We presented that challenge to the Johns Hopkins students last summer and gave them a set of requirements for this tool. They nailed every one of those goals. Their solution is very simple, elegant and more advanced than I expected. I thought their prototype was fantastic.”
The device is powered by battery and it features two coils of wire, one in the search probe and the other in a control box. When electric current flows through the two coils, each produces an oscillating magnetic field. Circuitry in the control box then compares the frequency of the oscillations in the two coils and translates the difference in frequencies of these oscillations into an audible sound. It emits a tone that rise when it approaches metal screw.
Orthopedic screws are used by orthopedic surgeons to hold the broken bone fragments together for proper healing. These are made of stainless steel or titanium alloy and are produced in different lengths. Their screw heads range from 3 to 7 millimeters in diameter. The screws need to be removed sometimes when they change their position from the original one and cause infection as well as pain. Sometimes it becomes very difficult to find those troublesome screws or hardware because of the sin and scar tissue, even with the help of X-ray. The small metal detector is designed in such a way that when it approaches the hardware, it steer the doctor's screwdriver into the right position for removal.
“When
The device is powered by battery and it features two coils of wire, one in the search probe and the other in a control box. When electric current flows through the two coils, each produces an oscillating magnetic field. Circuitry in the control box then compares the frequency of the oscillations in the two coils and translates the difference in frequencies of these oscillations into an audible sound. It emits a tone that rise when it approaches metal screw.