THREE GUYS AND A BETTER PEDICLE DRILL (Orthopedics This Week)
Garages and basements are iconic and sacred spaces in the history of technology. Ever since the September day in 1998 when the founders of Google set up workspace in Susan Wojcicki’s garage on Santa Margarita Avenue in Menlo Park, young men have pursued their disruptive technology dreams in just such spaces.
Three such young men are presently living and working in a basement and garage they have converted into a machine shop and laboratory, in Saint Paul, Minnesota. Their goal is to create a new tool for spine surgery, a hand-held device that, containing both X-ray capabilities and a drill, would allow a surgeon to more quickly and more accurately than at present, insert pedicle screws into vertebra. Screw systems for the stabilization of spines have, in recent years, become common in spine surgery.
The concept first occurred to David Chang, M.D., a neurosurgeon. When Chang read an article in the Saint Paul Pioneer Press about MIT graduate and inventor Nicholas Pawley in about 2006, he looked him up. The two teamed up with a third—Simon Mehalck—whom they describe as being “from another planet” to create Chang’s idea.
With a handful of patents securing their intellectual property the three began the process of creating a prototype of their idea. But, before they could begin, Pawley had to create the setting where invention could take place. As he said, “We had the ideas but not until we had the environment built up could we make progress. Our environment consists of living space where we make people comfortable. We work long hours and have the equipment required to manufacture this. Everything is built here. We have a complete machine shop in the garage and the ability to make these electromagnetic components. We create the software to manage the data that is produced.”
There is a steep learning curve associated with the insertion of pedicle screws in a spine. Implantation of the screws requires extensive tissue dissection to expose the entry points. The operative time is necessarily lengthened with the potential for significant blood loss and increased risk of infection.
The surgeon’s target is an area as small as a quarter of an inch that is often obscured by other tissues. Most surgeons are aided in their placement of the screws by external landmarks, made previously on the patient, and by two fluoroscopic views provided by a massive overhead X-ray machine. One fluoroscopic picture is taken from the side and a second from above. Chang says that the surgeon, staring at the computer screen, is guided in his screw insertion by the combination of the two X-ray shots and the landmarks. “That is OK,” he says, “but still not perfect.”
Pawley pointed out that the surgeon,” instead of having an extremely high resolution image of a broad area of the patient’s spine, with the device they were making would have a limited view of the region of interest which is all that is necessary.” Chang likens the process to peering down a tube until the surgeon sees a perfect circle with the dot in the center—which is the screw. The surgeon looks down the shaft, focuses on the circle and drops the screw in the center.
The prototype has yet to be finished. Attached to the body of it is a gyroscope and an accelerometer—both of which send data on the device’s movement to the controller which sends it on to the computer which in turn flashes it back to the device which guides the operator to the right place to insert the screw in the bone.
As Chang explains, their goal is to achieve better accuracy in placing screws than is presently achieved by the present practice of combining the fluoroscopes from two positions and the landmark markings to determine where to insert pedicle screws.” “Also,” he adds, “speed is a main thing.” Pawley can be reached at [email protected].