Monty Moshier first became interested in prosthetics at age 11, when his father lost his leg below the knee in a lumber milling accident. While Moshier was earning his Ph.D. in mechanical engineering from Purdue University, his father’s prosthetist asked for help with a new prosthetic foot he was developing, and Moshier’s path was set. He began consulting on prosthetic design and manufacturing and in 2006, he launched his own company, Makstride. (In addition to running Makstride, Moshier teaches aeronautical engineering and serves as chief technologist for a company that develops inspection systems to identify metal fatigue cracks.)
At first, Makstride designed and manufactured feet for distribution by another company, but in March of this year, Moshier formed a sister company, Makstride Prosthetics, to assume sales and marketing functions for its own products.
Makstride makes the BioStride series of prosthetic feet, a carbon fiber design that uses a reverse J shape for the shank, according to senior engineer Dallin Leach. “When you load the heel, it actually propels you forward instead of down or even backwards, as in other devices.”
“The Biostride foot doesn’t have an independent heel mechanism,” explains the company’s prosthetic technician Byron Claudino, a 25-year veteran of the industry and co-designer of Makstride feet. “It derives all plantar flexion at initial heel contact from the calf shank itself, simulating more normal human biomechanical ankle movement.”
The prostheses are made of carbon fiber with titanium fasteners and adaptors, all ISO tested to current standards, says Leach. “Tests show the shank on two models, the NaturalStride and ComfortStride, can accommodate up to 500 lbs., and there are not many of those on the market,” he said noting also that the prosthesis is lightweight, so it doesn’t place undue pressure on the socket and amputees residual limb.
Jennifer McCarthy, CP, is a clinical consultant at Makstride, where she assists with product testing on patients and offers clinical feedback to improve prosthetic design. “I also provide clinical support to customers and product training to our sales staff and to customers,” she says.
Facing the pylon toward the back, in contrast to traditional shanked feet, she says, “allows patients to feel less resistance when loading the pylon, which makes their gait more efficient and requires less effort to walk.”
Makstride introduced the next generation of its prosthetic foot – the Trekk and Trekk LP — at the AOPA National Assembly in October. The Trekk offers improved vertical shock absorption, says Claudino. “Its anterior-facing calf shank with multiplicity of elongated struts upon initial heel contact has plantarflexion and eversion movement. This movement is crucial to replicating more normal physiological shock absorption,” he explains.
“With the addition of the new keel and independent heel, at mid stance, the Trekk has little resistance to movement, so the ankle can move freely. This allows the plantar weight-bearing surface of the foot to stay compliant with the ground, creating more stability. Also, the overall increase in movement with less resistance greatly reduces inner socket shear forces. This means more socket comfort for the amputee.
“As the toe continues to load in late-stance phase, the anterior facing shank gets longer and helps keep amputee’s center of gravity at a more even level. It takes out the vertical movement, so you spend less time going up and down like a pogo stick and more time moving forward.”
From Scott Faulkenburg, a user of the Trekk, ‘The new foot is great – just used the foot on Kilimanjaro and it performed really well all the way to 19,340 feet! The foot was stiff enough to handle pack weights up to 60 lbs., yet was comfortable on the downhills. The new heel felt like a shock absorber coming down the mountain, which was a welcome change from the usual pounding heel strike that I have become accustom to with other feet.
And Moshier’s father? In spite of owning a bionic prosthesis, he wears the foot his son designed nearly every day.