The Project: To develop a torque-limiting wrench for a new cervical spine system under time and money constraints.
The Solution: Use 3D CAD software and the Internet to communicate design concepts by e-mail and then turn the 3D model into an exact replica of the part in a few hours.
By Lisa Arrigo, Editorial Director
Tara Ziolo's story is not unlike that of most mechanical design engineers working in the medical device market today. Her mission is to solve complex design challenges ever day. What is different, however, is how she handled a recent design project for her company, Electro Biology Inc. in Parsippany, NJ. The following "Case In Point" article examines how a particular type of software played a key role in Ziolo's work on a new cervical spine system.

Gauthier Biomedical's design concept in SolidWorks
Electro Biology Inc. is one of six business units of Biomet, the fifth largest producer of orthopedic products in the world. Specializing in electro and biomechanical medicine, the company designs, develops, and manufactures products used primarily by orthopedic medical specialists in both surgical and non-surgical therapy. About a year ago, Ziolo needed a specific torque-limiting wrench for a new cervical spine system. Because of the nature of the project, she asked Gauthier Biomedical in Grafton, WI, to assist in the design process. Gauthier Biomedical's expertise is designing, prototyping, and manufacturing handheld surgical instruments for medical device OEMs.

"We provided a solid non-torquing handle to Gauthier and asked if they could put a torque mechanism in that handle," explained Ziolo. "We were hoping they could provide a torque mechanism that would be in the range of 5-10 in.-lbs. I was open to changes in the handle's geometry, yet I wanted to give Gauthier an idea of what handle size I was looking for."

Gauthier Biomedical used the Internet and the 3D CAD software program SolidWorks to communicate its design concepts to Ziolo and then, before building a functional prototype, produced detailed 3D models to show her exactly how the mechanism would look. "After working back and forth on design concepts, Gauthier was able to come up with a perfect torque mechanism that would fit in a handle we both agreed upon," recalled Ziolo. "Obviously, the communication channel they created saved us both time and money."

This communication channel also allowed Ziolo to make last minute changes to prototypes and pilot runs. This was significant since Ziolo was facing time and money constraints. Her ability to have direct input into all phases of design streamlined the entire process.

The president of Gauthier Biomedical, Michael Gauthier, summarized the process as follows: "In order to provide an exact replica of what our clients are looking for, we communicate our design concepts using SolidWorks. We then provide a 2D drawing in either a DXF or a PDF file format along with a 3D file in a number of different formats and photographic renderings for the customer to view through e-mail."

Example of the 2D drawings sent in either DXF or PDF file format
(click the image to enlarge)
Sending clients, such as Ziolo, these types of files lets them review the product and make changes. Files can be printed in three dimensions to produce a full-scale rapid prototype of the final instrument, which shows how the part will look and function. In other words, the files represent exactly what Gauthier Biomedical can produce. The CAD files and photos also allow clients to review plans for the prototype with other engineers, designing surgeons, and marketing groups before production begins.

"In my opinion, the 3D modeling was crucial in saving us time," said Ziolo. "On our computer, we were able to see in three dimensions what the finished part was going to look like rather than having to piece together 2D drawings in our minds. I was also able to take Gauthier's solid model and make a rapid prototype — which is a plaster and glue replica — in a matter of a few hours. The rapid prototype allowed me to hold a solid model in my hand and feel what the handle was going to be like before spending the money to build a functional prototype."

For additional information on the products and technologies discussed in this article, see Medical Design Technology online at and the following websites:•••