Lost screws found

Johns Hopkins undergraduates have invented a small handheld metal detector to help doctors locate hidden orthopaedic screws that need to be removed from patients’ bodies.

The device emits a tone that rises in pitch as the surgeon moves closer to the metal screw. It also serves as a surgical tool to guide the removal of the hardware.

Orthopaedic screws, usually made of a stainless steel or titanium alloy, are produced in varying lengths and can have screwheads that range from roughly 3 to 7 millimetres in diameter. Orthopaedic surgeons often use these screws and related hardware to hold broken bone fragments together for proper healing.

These doctors often need to remove orthopaedic screws that shift position, trigger an infection or cause pain, but skin and scar tissue can make it difficult to find the troublesome hardware, even with the aid of real-time X-ray technology. The small handheld detector is designed to zero in on the hardware and steer the doctor’s screwdriver into position for prompt removal.