Cambridge, MA--To access the frontal or maxillary sinuses, surgeons navigate through the patient's nostril with various instruments. Depending on the sinus' location, getting in there can be difficult and time consuming for the doctor, and may result in tissue trauma to the patient. These challenges led Thomas Davison, Endius Inc.'s president and CEO and his staff, to develop steerable instruments for use in sinus surgery.

"It's like the sinuses are rooms off of a long hallway. You have to make sure you go through the right doors to get where you want to go," Davison explains. Endius' initial prototype-design had approximately 50 parts, and cost about $2,000 to build. Endius turned to Product Genesis Inc., an engineering design and product development firm with expertise in industrial design and general engineering, to "productize" the prototype.

Using CAD and SLA, Product Genesis reduced the 50-component prototype to less than ten parts, and cut the cost from thousands to only a few dollars per device. The devices' advantages include:

- Faster, easier access to the surgical site

- One multi-functional instrument replaces several

- Reduced trauma to tissue when inserting and removing instruments

- Access to maxillary and frontal sinuses

- Improved tip visibility

- More convenient endoscopic follow-up in the office

According to Chris Zirps, vice president of technical development for Product Genesis, "We had to take a step back from the prototype and ask ourselves if there was an easier way to accomplish the same thing." The main challenge was reducing cost. Going to injection molding and simplifying design made the device as manufacturable as possible. "In the end, we came up with something far simpler than Endius had in mind."

"We eliminated all the adjustment devices inside the handle, and simplified it to a three-piece assembly," Zirps explains. A trigger with integral spring controls the opening and closing of the jaw, and a thumb-controlled capstan with a plastic spring around it, controls the radius of curvature at the tip.

"While the basic structure of the vertebrae was pretty good," recalls Zirps, "each piece probably cost on the order of $100 to make. Injection-molding technology let us reduce total cost to less than 70 cents." The other big challenge was to figure out how to design disposable jaws. These jaws make up most of the total cost. The key to reducing cost was coming up with a scheme to simplify the jaw-hinge joint as much as possible. "We use a piece of nitinol wire, soldered to the pivoting jaw to avoid a clevis and extra hinge pin," explains Zirps.

PTC's Pro-Engineer was used throughout the process. "It helped a great deal in getting to the new pre-production prototype. We relied on SLA models, early in the design, to make sure everything fit together. Then we went to CNC-machined parts that were used in the clinical testing." The machined versions were very close to the real thing. "We took the feedback from the clinicals, and once the design changes were approved by Endius, we went directly to molding. Pro-E is a good tool to transfer the information to the mold maker," Zirps adds.

When choosing an outside design firm, Davison says, he looks at their track record for predicting costs and the length of time the project will take. "Product Genesis' people told us they could do it for a certain cost and in this amount of time. We knew that for us to do the same would take three times as long and three times as much money," Davison explains.

According to Brian Vogel, senior vice president at Product Genesis, "Our role included visits to vendors and the selection of vendors, which we did together with Endius. Later, our engineers made sure the tooling was done properly. We worked together with the other outside resources to make sure that we got the right parts on time, and that they went together properly. We also had an engineer at Endius' facility the day the first production unit was assembled. We have learned that if you manage the schedule, the hours and the dollars will take care of themselves. But if you simply measure the hours and the dollars and don't take care of the schedule, you'll get burned."

Additional details...Contact Thomas Davison, Endius Inc., 23 West Bacon St., Plainville, MA 02762; (978) 695-0983

Other Applications

- Cutting forceps

- Biting forceps

- Endoscopic surgery