The drill guide.
The drill guide.

Engineers at Wright Medical Technology wanted to increase the value of their PRO-DENSE bone-grafting paste by offering surgeons a set of disposable, pre-sterilised surgical tools for performing specific ankle procedures. They turned to RTP Company for help with designing one of the instruments – a retrograde drill guide for the ankle.

A drill guide had never been made in a disposable plastic form before. Because the device needed to be very stiff and dimensionally accurate to facilitate the delicate surgery, Wright Medical engineers doubted it was possible, much less at a disposable price.

"We were prepared to manufacture metal drill guides, even though we realised that providing an incomplete disposable kit that needed a separate reusable piece was a less than elegant solution," explains Ryan Belaney, Wright Medical's Product Development Engineer. "We had worked with RTP Company before
and knew they were effective problem-solvers, so we figured, 'let's see what happens.' "

RTP Company recommended two candidate materials that met Wright Medical's stringent stiffness requirements. Both were RTP 300 Series glass fibre reinforced polycarbonate (PC) compounds providing ISO 10993 compliance to meet biocompatibility requirements.

"We tried them out in a cadaver lab, and all the surgeons agreed that the guides worked very well and performed in the same manner as a metal guide," reports Belaney.

Wright Medical decided to go with the higher glass loaded version in order to give an extra measure of stiffness.

The material's cost was also positive.

"We found that we would be able to manufacture plastic drill guides for less than half the cost of a metal version, handily meeting our desired price point for disposables," Belaney says.

An added bonus was that precoloring the compound gave Wright Medical the ability to brand the device in its custom teal colour.

Wright Medical Technology, based in Arlington, Tennessee, USA, is a global orthopaedic medical device company specialising in the design, manufacture, and marketing of reconstructive joint devices and biologics.

RTP Company, headquartered in Winona, Minnesota, USA, is a global compounder of custom engineered thermoplastics.