O&P Innovation Links Humans With Animals

From four legs to two legs, all creatures benefit from the same orthotic and prosthetic care.

Dogs, horses, birds and elephants are not the typical patient list for an O&P practitioner. It even might be difficult for some to find similarities in the anatomies of these animals and typical O&P patients.

Some O&P practitioners have excelled in their work with animals, however, and have found that it enhances their ability to care for human patients. The opportunity provides them with the ability to think critically and solve a problem in a different way.

O&P Business News explored the benefits to humans of caring for animal patients.

Animal work

Kevin Carroll, MS, CP, FAAOP, vice president of prosthetics for Hanger Prosthetics & Orthotics, has worked with quite a few types of animals over the years. He is one of a team of professionals at Hanger — including Dan Elseroad, Robert Greco, CO, Doug Hackert, CP, Kirby Shelton, CO, Kyle Sherk, CP, LPO, and Daniel Strzempka, LPO, CPO — who come together to treat animals in need of O&P care.

From birds — including an ostrich — to horses, from dogs to a dolphin, the Hanger team has worked to repair and replace limb function, with much success.

“They are not doing this for money. They are doing it purely for the love of the animal,” Carroll said.

One of the patients, Winter the bottlenose dolphin, became somewhat of a celebrity, and people around the country learned a little bit about the O&P world through her story. Those who might otherwise not come into contact with amputees shared Winter’s triumphs in replacing the missing piece of her tail.

According to USA Today, Winter lost her tail in 2005 after being caught in a crab trap. Carroll, who operates out of Orlando, Fla., offered to create a suitable replacement.

Dolphin with silicone tail
Images reprinted with permission of Hanger Prosthetics and Orthotics Inc.

Carroll’s and Strzempka’s efforts gave Hanger the opportunity to develop a new prosthetic device, a silicone tail, which the team combined with a special gel liner to create the necessary waterproof seal. Winter now thrives with her new tail.

It was not long before Carroll was able to put his experience with Winter to practical, human use. The same year Winter lost her tail, Carroll began working with Senior Airman Brian Kolfage, who became a left hip disarticulation, right transfemoral and right transradial amputee when he was injured in Iraq in 2004. Carroll’s new challenge was to help Kolfage walk again.

Because of severe heterotopic ossification on both sides of his body, Kolfage was in pain when using any type of prosthetic devices. Carroll tested Winter’s gel liner, which drastically improved Kolfage’s prosthetic fit. In the absence of pain, Kolfage was able to learn to walk again and become more independent than anyone thought would be possible.

(For more information about Kolfage’s recovery, see “Powered by Mere Inches,” in the Jan. 15 issue of O&P Business News.)

In the spotlight

It was a chance phone call that brought Dwayne Mara, CP, BOCP, into the world of animal prosthetics. After Hurricane Katrina hit the Gulf Coast, Kaye Harris rescued a pony named Molly and a number of other animals. One day, Harris returned to her farm to find that Molly had been attacked by a rescued pit bull, and was severely injured.

Molly’s veterinarian, Allison Barca, DVM, repaired the injuries she could, and prepared the pony for surgery to amputate her right front leg. Barca phoned Mara, owner of Bayou Orthotic and Prosthetic Center in Metairie, La., to see what he could do to help once Molly became an amputee.

“My reaction was, ‘A what?’” Mara said. “I had never dealt with any type of animal prosthetics. But if Molly had the surgery, I would give it a shot.”

After completing her amputation, doctors placed Molly in a temporary prosthetic leg.

Mara approached his new patient’s case as if he were dealing with a human patient, keeping in mind her weight. Because Molly’s weight distribution for each of her four legs resembled that of human weight distribution, he was able to place her in human componentry.

First he tried what would be most comfortable for a human patient: a silicone locking liner. He found that the liner prevented some of Molly’s other wounds from healing because of her skin and hair, and because of her outdoor environment. Mara immediately changed the plan, and decided to go back to basics.

“I used plastics instead of lamination or carbon fiber. We used a cushion liner between the horse and the prosthesis,” he said. “I had to completely change my format. I actually went back to conventional technique.”

Dolphin with silicone tail Dolphin with silicone tail

Surgical options

Another increasingly viable option for these animal amputees is osseointegrated implants. Denis Marcellin-Little, DEDV, and Ola Harrysson, PhD, both from North Carolina State University in Raleigh, have been collaborating on these procedures in both cats and dogs since 2002.

One of their recent patients was Cassidy, a mixed breed dog who came to his owners with a transtibial amputation of his right hind leg. The owners, who live in New York, found information about the work being done at N.C. State on the Internet and reached out to see if Cassidy was a candidate for osseointegration.

“Walking on three legs for a big dog can be fairly demanding and he had limitations in his ability to walk around,” Marcellin-Little said.

Because of the dog’s condition and his owner’s dedication to his care, the team at N.C. State decided to take on the case.

Before beginning invasive surgery, the team always evaluates its patients for other options. Marcellin-Little, associate professor of orthopedic surgery in the College of Veterinary Medicine, and his team conducted orthopedic and physical exams, and did radiographs and a computed tomography (CT) scan of Cassidy’s residual limb, as well as of the opposite pelvic limb for a reference. From this information, Harrysson, associate professor in the Fitts Department of Industrial and Systems Engineering, and his team, including PhD candidates Tim Horn and Jessica Springer, developed an external prosthesis with a custom silicone liner.

Harrysson and the engineering team took Cassidy’s CT scan and made 3-D computer models of the bone and of the soft tissue. They used rapid prototyping machines to build the bones and a mold of the soft tissue, and casted that replica with ballistic gel, which they then used to design the custom liner.

Unfortunately, Marcellin-Little told O&P Business News, Cassidy was unsuccessful ambulating with the external prosthesis. In many cases, this happens when working with only the proximal portion of the tibia, as in Cassidy’s case.

The team reclassified Cassidy as a surgical patient and designed an osseointegrated implant. Once the osseointegration was completed, Cassidy’s owner and the N.C. State team worked together to train the dog to walk on his new legs, over a period of weeks.

Cost considerations

Dolphin with silicone tail

Marcellin-Little expects that, at some point in the future, those involved with this type of work will create a cost-benefit ratio showing that a customized osseointegrated implant leads to fewer complications and might last a lifetime. Until then, he said dog owners will pay a few thousand dollars for osseointegrated implants; even now those cost less than total hip replacements, which are performed routinely in dogs.

“It is not so complex and expensive that it should be discarded as an idea before it is fully explored,” he said.

Harrysson agrees, and imagines the cost will be comparable once consistently implemented in humans.

“I think that, if you start to implement this in humans, the cost would be similar to what a total knee [replacement] or a total hip [replacement] would cost,” he said.

In addition, the more often they perform these procedures and design these devices, the less time they will take — and therefore, less money they will cost. Harrysson’s goal for any custom implant is a 2-day turnaround time, where they receive a CT scan and have an implant ready to be sterilized in 2 days.

More important to this discussion, Marcellin-Little said, is the point that osseointegration will not eliminate external prosthetic devices, in animals or in humans. Instead, he wants patients to have this option.

“It is an exploration of an alternative, promising, I think, because of early success,” he said.

New challenges

The benefits to animal patients are clear: they receive a device that enables them to walk, swim or otherwise move as nature intended. Orthotists and prosthetists offer the technology, the knowledge of orthotic and prosthetic systems, and the experience to properly fit comfortable custom O&P devices.

There also are multiple benefits both to the O&P practitioner working with the animal and to human patients in general.

First, practitioners are able to solve new and difficult problems. Although practitioners like Mara and Carroll have years of experience fitting patients, they did not have experience dealing with patients with four legs up until this point. And as important as waterproof prosthetic components are to swimmers and to other patients who spend time in the water, those components are even more integral to an animal living in the water. If an O&P device can be waterproof for a dolphin, then it probably can withstand the water pressure from a patient’s scuba diving hobby.

Practitioners who work with animals also see old challenges with fresh eyes. Because the situation is completely unlike anything they have seen before, practitioners are unable to use the same solutions over and over. They are forced to approach the task — fit the patient with a prosthesis — differently than ever before — because the patient has four legs, fins or wings — and this encourages brainstorming and thinking unconventionally.

As in the example of Winter the dolphin’s prosthetic liner being used to help Kolfage learn to walk, practitioners can find more than one use for components. The discovery of new materials to solve particularly challenging animal cases also will benefit human patients in time. The initial innovation is the hurdle; once cleared, it paves the way for any number of applications.

Stronger materials

A multidisciplinary approach to treating these patients ensures they benefit from the same level of care in each discipline: state-of-the-art surgical procedures and prosthetic fit.
Image reprinted with permission of Hanger Prosthetics and Orthotics Inc.

Specifically referring to larger animal patients, stronger materials also can be used with human patients.

“When we try new things on a human, it sometimes happens that we have to put our heads together and come up with stronger materials,” Carroll said. “But if we are doing the same research on an animal to come up with a strong material — if the animal isn’t breaking it, it is pretty likely that our human [patient] is not going to break it.”

As such, the prosthesis or orthosis that is strong enough to hold up a horse certainly will contain materials to hold up to both strenuous athletic activity and bariatric patients exceeding the weight limit of conventional prosthetic devices.

“We learn from that application how to have a relatively durable and stronger-built orthotic or prosthetic device,” Carroll told O&P Business News. “As we all know, the bariatric population here in the United States is growing. That is a group of important individuals who often need to be cared for.”

He also has been working with his son, Michael, to design systems for the care of elephants. With from 10,000 to 20,000 pounds of weight resting on their legs, elephants often damage their feet. Carroll is working on devices that will serve as protectors for elephant feet.

In addition to the weight issues addressed in this international project, Carroll wants to protect the animals’ skin, which would serve to solve skin irritation issues in human patients as well.

Multidisciplinary approach

The discovery of new materials to solve particularly challenging animal cases will benefit human patients in time.
Image reprinted with permission of North Carolina State University College of Veterinary Medicine.

O&P practitioners involved with the orthotic or prosthetic care of an animal must realize that this animal will need follow-up care for the rest of its life, just as a human patient would require. In addition, practitioners should be prepared to work alongside various animal care professionals, including the animal’s owner, veterinarians, technicians and any animal husbandry groups.

This approach gives new meaning to the term multidisciplinary.

“We find ourselves working with a unique and passionate group of individuals. These are people who have dedicated their lives to the well-being of animals,” Carroll said. “It is almost like working with a parent. When we work with a parent, they have that same passion for their child.”

A multidisciplinary approach to treating these patients ensures they benefit from the same level of care in each discipline: state-of-the-art surgical procedures, sound manufacturing, and proper orthotic and prosthetic fit.

At N.C. State, each member of the team provides input into all levels of the procedure.

“The surgeons are part of the design process, constantly giving feedback. Then, once we come to the surgery, the engineers are in the operating room, taking notes, to constantly try to improve the design,” Harrysson said. “I think that is one of the reasons we are progressing fairly rapidly.”

Those involved in orthopedic surgery, O&P manufacturing, and orthotic and prosthetic care might find significant benefits for patients if they collaborated in this way, instead of maintaining their loose professional affiliation.

“It is collaborating together for the same goal. It is a luxury,” Marcellin-Little said. “That is one of the advantages of being a veterinarian in some ways … you do not feel constrained by conventional approaches to things.”

Benefits to O&P

Because Molly’s weight distribution for each of her four legs resembled that of human weight distribution, he was able to place her in human componentry.
Image reprinted with permission of Dwayne Mara.

The N.C. State team recently added a new team member who might benefit from this work more than anyone else. Jeffrey Huber, a sophomore engineering student, was born a transtibial amputee and has lifelong, firsthand experience with prosthetic devices. Huber plans to enter the O&P profession when he graduates, but also jumped on the opportunity to see the field through the eyes of animal patients.

“He is interested in how we can use modern manufacturing, like the rapid prototyping technologies, to design and make external prostheses faster and to get a better fit,” Harrysson said.

Huber also wants to explore osseointegration, because he sees its practical application in other patients. When he graduates, he might have the opportunity to again work with this procedure — in humans.

Marcellin-Little would encourage this effort because osseointegration is here to stay, he said. It will become a more routine procedure as orthotic, prosthetic and orthopedic engineering and manufacturing become more sophisticated.

“I would not say this is going to take many years. It might happen in a few years,” he said.

In the meantime, Carroll and Strempka have found another application for the work they have done with Winter the dolphin, and are now using the lessons of her rotational stability on human patients. Without this project, they may not have reached this point for 5 or 10 years. The veterinary team has ideas that might not have made its way to the O&P world without this interaction.

“I want to let people see the positive aspect of working with animals,” Carroll said. “We just learn so much. What other job could you get up every day and have something thrown at you that’s totally different?”

And, he asked, “Where would the world be without animals?”

Stephanie Z. Pavlou, ELS, is a staff writer for O&P Business News.

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