A New Approach to Trimming CAD/CAM Prosthetic Sockets

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By Vardan Gazarian, CPO

With computer-aided design (CAD) becoming commonplace in O&P, it behooves us to examine whether our existing processes are still the most efficient when it comes to the manual tasks of fabricating a prosthesis.

For example, one of the manual tasks we perform is trimming prosthetic sockets off the positive foam carvings.
Traditionally we have trimmed prosthetic sockets using an electric or a pneumatic oscillating saw. There are downsides to both: Electric oscillating saws are typically not robust enough for repeated heavy-duty lab use, but using a pneumatic oscillating saw often requires waiting for the air tank to re-pressurize for full sawing power and speed, thus interrupting the process. 

I found using a band saw with a tilting table to trim plastic and laminated socket off CAD foam carvings to be less time and labor intensive when compared to using an oscillating saw. The method can be applied to the laminated and plastic transtibial and transfemoral sockets that are fabricated on foam carvings.

The method cannot be used with plaster positive molds. The advent of CAD foam carving presents a unique opportunity to utilize a band saw to trim the sockets, which makes the task a lot more efficient. I don't have a carver in my clinic at the time of writing this article, and I use a central fabrication facility to carve positive molds and vacuum form test sockets. Because most of the fabrication takes place remotely, I found it to be more effective for me to receive the socket on the carving and trim it in my clinic. 

The tools needed for this trimming method are a band saw and arbor grinder, such as a Troutman, with your preferred sanding and buffing arbors.

The step-by-step instructions are as follows:

Vardan Gazarian, CPO, is a clinical operations director for Stellar Prosthetics and Orthotics in Pasadena, California. He can be contacted at vgazarian@stellarpo.com.