You’ve probably seen dogs moving around on three legs, but you may be unaware of the ramifications as they age. They often develop arthritis in their hips and other joints, which can deplete their energy, leave them house-bound and affect their well-being.
“I’ve witnessed animals saved through amputations only to see them struggle to lead normal lives,” says Bill Bickley, a licensed orthotist and prosthetist. “I thought the use of CFRP prosthetic limbs like those of Olympic athletes could advance animal prosthetics.”
In 2013, Bickley founded Pet Artificial Limbs & Supports (PALS) Houston. While others were offering animal prosthetics, there was no equivalent to the CFRP blades Bickley had in mind. “CFRP offered improved strength and flexibility that would provide freedom and put more life and bounce into the steps of our four-legged friends,” says Bickley.
His search for expertise to integrate CFRP into the compound curves of prosthetic blades led him to Hans deBot of deBotech, Inc., whose experience developing CFRP parts for aerospace, marine, motorsports and even Olympic bobsleds impressed Bickley. deBot wholeheartedly agreed to help. “I am a dog lover myself, and my family currently owns three dogs,” he says. “I understand that there is no better friend.”
Bickley and deBot had little information and no data on the load requirements for the initial design of a CFRP animal prosthetic. A few preliminary requirements were clear. The length of the blade needed to make up the distance between the residual limb and the ground. The blade also needed to compensate for the animal walking, then running. In addition, the design required varied stiffness and flexure rates from the top to bottom of the blade, with higher rigidity and strength at the mounting position for robust, weight-bearing performance and increasing flexure rates down the length of the blade to mimic the animal’s joint. The final result needed to be flexible when the animal was walking and provide an immediate input of power and energy absorption when the animal ran.
Bickley and deBot designed a prosthetic with a hollow polypropylene cup equipped with an aluminum mounting plate that slips over the residual limb and is held in place with Velcro® straps. The CFRP blade is then affixed to the mounting plate with screws. The lower end of the blade attaches at the bottom to a plastic “paw” with a rockered bottom covered with a non-slip material such as rubber to form the sole. The paw (which is subject to wear) is replaceable, while the CFRP blade is designed to last the animal’s lifetime.