Rice University seniors at the Brown School of Engineering are helping doctors repair fractured, long bones in an arm or leg by incorporating magnets to set things in place.
The researchers call themselves Drill Team Six and chose this topic based on an idea pitched by Dr. Ashvin Dewan, an orthopedic surgeon at Houston Methodist Hospital. Dewan wanted to simplify a procedure in which titanium rods are placed inside broken bones, making them more functional.
With the help of Dr. Dewan, the researchers learned that surgeons often require numerous Xrays to locate pre-drilled 5-millimeter holes in the titanium rods. The holes allow the surgeons to secure the rod to bone fragments that hold them in place.
A typical surgery usually consists of doctors inserting a long rod with a guided wire to the end of the bone and drilling through the marrow to align the fractured fragments. After this, the surgeons depend on Xrays, and a bit of trial and error to drill long surgical screws through one side of the bone to secure it to the other side. Trial and error integrated in a surgery is probably not something many patients enjoy hearing.
The team, which consists of bioengineering majors Babs Ogunbanwo, Takanori Iida, Byung-UK Kang, and Hannah Jackson, and mechanical engineering majors Will Yarinsky and Ian Frankel, set to work at making this process easier.
“We want to reduce the amount of X-rays, the surgeon’s time, the operating room time, the setup time, everything,” Yarinsky said.
When coming up with a solution, the team made the wire adjacent to the holes magnetic, so they could align automatically. Neither the skin nor bone would hinder this magnetic field.
“That way, the magnets hold their position and we can do the location process,” said Frankel. “Once we’ve found them and secured the rod, we remove the wire and the magnets with it.”
The outside mechanism consists of a brace that can be attached to an arm or leg using Velcro. A mounted sensor is then moved along the 3D-printed carbon-fiber rods, or around the limb, until the magnet is located. Once in position, the angle of the sensor can be adjusted. When all three degrees of freedom are in alignment with the target magnets, a virtual LED lights up on a display wired to the sensor. The sensor is then removed and a drill keyed to the mechanism is inserted.
“We do the angular part because the rod is not in the center of the leg, and the hole is not necessarily perpendicular to the surface,” said Yarinsky. “The rod is about 10 to 20 millimeters thick and has a hole on one side and a hole on the other. We don’t want to hit the first hole at an angle where we miss the second and don’t go all the way through.”
So far, the team has tested their device on a mannequin’s wooden leg and implemented a system to check the accuracy of their device.
Before this can be used in hospitals, the team said the device will need FDA approval.
“I’m very impressed with what the team put together,” said Dewan. “Where we ended up is completely different from what we imagined, but kudos to these guys. They went through many different proposals and ideas and ended up running with the one that seemed most promising.”
