Alberta Inventors and Inventions - Laser Digitizer System for Producing Prosthetic Devices

People who are without one or more limbs encounter a host of challenges in their day-to-day lives. Prosthetics serve to make these obstacles a little easier to overcome by substituting a leg or an arm. Most artificial limbs require a socket that fits onto the body of a patient; these are custom-made to fit the individual shape and special needs of an amputee. Considered to be the most difficult step in creation of a prosthetic, a socket’s construction requires talented technicians with skill and experience. Traditionally, sockets for a prosthetic are built by taking a mould of the body part to form a positive replica. The shape of the positive is altered to accommodate sensitive areas and increase the load for other areas such as bony protrusions that are able to take more pressure. A socket is then built from the positive and attached to a prosthetic.

George Clynch, president of Clynch Technologies Inc. in Calgary, was unsatisfied with this method and set out to develop a way of making better sockets. With help from several institutions including the University of Calgary and the Alberta Research Council and funding from the Alberta Heritage Foundation for Medical Research and the Workers Compensation Board, Clynch began work on a digital imaging process in 1974 that would replace the cast and mould system.

Initial tests weren’t as positive as he had hoped. Clynch tried various methods including ultra sound and MRI, ultimately teaming up with a California company to develop a non-contact laser scanner and software specifically for his idea. The end product includes a state-of-the-art laser camera and is used in practices around the world.

George Clynch scans a patients leg using his patented laser scanning process

To begin the process, the patient pulls a cover, in many cases a white nylon stocking, over the amputated limb. This provides a reflective surface that will relay measurements and other information into the laser scanner. Non-reflective markings are placed over the surface of the stump, on soft spots and bony protrusions that require a modification to the socket. The limb is scanned and data is presented digitally so that technicians can alter measurements by increasing or decreasing the pressure that would be placed on an individual marker. A code is produced and entered into a cutting machine that creates the mould for the socket.

George Clynch and computer programmer Curt Perry using the lazer digitizing system.

Though this method allows technicians to take the digital images, the socket is usually not produced on-site. The image is sent electronically to a central fabrication centre where a specialized milling machine will produce the apparatus. The socket can be manufactured and shipped out the same day, arriving back at the original clinic for fitting the next morning. This central production centre cuts costs and guarantees quality control.

The laser scanning system has proved to be very successful in the field of prosthetics, but could potentially be applied to many other medical specialties such as oncology, plastic surgery and helmet manufacturing.