Improving Fit + Function for the Hip Disarticulation Patient
Mike Corcoran, CPO, cofounder of Medical Center Orthotics and Prosthetics, headquartered in Silver Spring, Maryland, says he still remembers feeling overwhelmed when he treated his first patient who had a hip disarticulation.
"When the patient walks through the door and you've never seen [this type of presentation] before, you don't even know where to start," says Corcoran, whose company contracts to treat patients at Walter Reed National Military Medical Center, Bethesda, Maryland.
Just 1 to 2 percent of all prosthetic patients have this type of amputation,1 which involves either leaving a very small portion of the femur or separating the ball from the socket of the hip joint. The presentation is so rare that many prosthetists never have a case in their entire careers. For those who do, traditional treatments historically don't offer great outcomes. Much of the recent literature on the subject cites a 1983 study that found that just 25 percent2 of all hip disarticulation patients use a prosthesis, and of those, many end up abandoning it after finding it too uncomfortable and difficult to use.
It's no wonder that hip disarticulation prostheses have not been well received by patients in the past, Corcoran says. The traditional prosthetic solution he was taught included strapping a bulky bucket-like socket to the patient, which made walking twice as hard. Also, if the patient sat down, it felt akin to sitting atop a fence post, he says. "The textbook solution is not a solution."
Without books to guide him in fitting his first patient with a hip disarticulation, he sought the advice of faculty from his alma mater, the Northwestern University Prosthetic-Orthotic Center (NUPOC), Chicago, Illinois, and the clinical staff at Ottobock, Minneapolis, Minnesota. "I went to Northwestern University and you didn't see any patients like that, you just read about them," he says. "They teach you as much as they can through lectures and texts, but when it came time for me to fit the patient, it felt like I was reading a manual about flying a plane while I was in a cockpit up in the air."
Even with all of the advice and recommendations, the patient still wasn't as comfortable or as mobile with the prosthesis that Corcoran made as he would have liked. "The challenge was that the patient wasn't going anywhere," he says. "I had to remake [the socket], and remake it, and eventually got it right."
His journey to find a solution outlines the twofold problem for prosthetists treating patients with hip disarticulations: the rarity of the amputation, and the nature of the amputation that makes finding a comfortable, workable solution for a patient much more difficult than prosthetic interventions for other types of amputations. So the average prosthetist treating a patient in this population has to do one of the most complicated fittings possible and, in general, has little to no firsthand experience.
Despite the challenges, experts in treating these patients say new advances in socket design and technology now enable many patients to walk independently. Some have even better outcomes. Zach Harvey, CPO, managing prosthetist at the Denver, Colorado, branch of Bulow Orthotic and Prosthetic Solutions (Bulow OPS), has a photo of one of his hip disarticulation patients bungee jumping, and Bobby Latham, CP, BOCO, of Bulow OPS' West Columbia, South Carolina, patient care facility, has a patient who is planning to run races.
"When I talk to these patients, 90 percent of them say their doctor told them they would have to use crutches or a wheelchair," says Stan Patterson, CP, founder of Prosthetic & Orthotic Associates of Central Florida (POA), Orlando. "That's what the doctors were taught in school, and many are not aware of the newer prosthetic socket designs and component options available today."
Harvey says that prosthetists who have had successes with this patient population need to share their knowledge for the benefit of other prosthetists and their patients. "A lot of people are still doing the old style, unfortunately," he says. "There's definitely a need for more education and knowledge throughout our field to share these successes," Harvey adds.
Working Toward a New Solution
Unfortunately, one of the reasons that there were not a lot advances in the treatment of these patients in the past was because the manufacturers didn't have a monetary reason to invest, Patterson says.
Since patients with hip disarticulations make up such a small percentage of the prosthetic population, there's not enough demand for products specific to their unique needs. "The prosthetics industry is not going to put too much money into this because the numbers are too minute," Patterson says.
Scott Sabolich, CP, LP, owner of Scott Sabolich Prosthetics & Research, Oklahoma City, Oklahoma agrees. "It's kind of a no-brainer; they're not going to be throwing tons of money because there's just not a lot of these patients and even less who wear a prosthesis," he says.
However, there has been a renewed focus on treatment since the wars in Iraq and Afghanistan, says Corcoran. Medical advances mean soldiers who may have died from their injuries in the past, including those with hip disarticulations, are returning home, and their prosthetists are looking for workable solutions. "I guess the silver lining in these two conflicts in Iraq and Afghanistan is that it has propelled the prosthetists at Walter Reed to come up with a solution," Corcoran says.
All of the experts interviewed had slightly different methods for treating their patients, but they all agreed that the best results require a comfortable socket fit and high-tech prosthetic componentry to help the patient minimize his or her energy expenditure. Both are necessary, Corcoran says, "If you have the best-fitting prosthesis and the work to ambulate it is so consuming, then it doesn't matter. Conversely, if you have the best technology but the socket isn't right, it will render the prosthesis useless too.
A Comfortable Socket
Getting a comfortable socket fit is one of the most difficult and most important parts of the process, the experts say. The difficulty is that the requirements of the perfect socket fit seem to contradict each other Harvey says. "It has to be tight and secure so [it is] not slipping around, but it also has to be comfortable when the [user is] sitting." Getting the right fit is compounded by the diverse amputation techniques used by surgeons. Hip disarticulations often stem from a traumatic injury, when the surgeon is more focused on saving the patient's life than planning for his or her ability to wear a prosthesis in the future, Corcoran says. That means that every patient will have a different build and different bony prominences, and could have sensitive nerve endings, which the surgeons may have buried in various places under the muscle and skin near the amputation area. "The one thing I can tell you about working with this patient population is that there is no...one definitive system that fits everyone," Corcoran says. In essence, prosthetists have the challenge of fitting a diverse patient group and finding a comfortable socket design that will work for most of this patient population.
In older, traditional designs, heavy sockets were constructed of rigid materials that had to be tightened so much that some patients suffered cracked ribs, Patterson says. Trey Martin, CP, LP, with Scott Sabolich Prosthetics & Research, says it was almost impossible for patients to be comfortable wearing them. "It would be similar to spending your day wearing a corset with weights attached," he says. These days, many prosthetists opt to make the prosthesis as light and moveable as possible while still maintaining stability.
"This is a patient population where every little bit counts," Harvey says. "Everything we can do to...lighten [the socket] up or use new materials goes a long way."
One of the most comfortable fits Harvey says he has found for this patient population is when the prosthetist cuts out the nonessential parts and uses flexible plastics as an interface. He stays away from the traditional flat socket, which puts pressure on the ischial tuberosity, which is not meant to bear weight, and also is more likely to allow the bone to slide off the socket.
Harvey says he prefers using a socket design he learned from Marlo Ortiz, CP(M), who designed the Marlo Anatomical Socket (MAS) for patients with transfemoral amputations. Ortiz later modified his design to encapsulate the ramus in four dimensions to help patients with hip disarticulations.
"This makes a pocket for the bone to sit into, and it's containing it from both sides and it's pushing up on the soft tissue on the outside," Harvey says. "The result is a much more comfortable and secure design."
However, prosthetists have to compress the soft tissue to ensure an intimate socket fit and also focus on the coronal and sagittal planes during casting. "Traditional designs focused on just the sagittal planes during casting and were fit by using 45 degree wedges in front and back to get a tight dimension," he says. "That's still really important; you need a tight fit. [The MAS adaptation] looks at things more in the coronal plane and gives you medial/lateral stability and comfort."
Latham also uses the MAS design and says that to do the fitting, he first wraps his patients in plastic wrap then uses elastic webbing horizontally to compress over the top of the iliac crest, and then adds another layer of elastic webbing from the groin over the shoulder to show the medial aspect of the ischium. He also does a two-stage cast where he first wraps fiberglass around the iliac crest and then, when dried, wraps around the amputated limb area.
"Even with all of this, when I did my first test socket it was very loose," Latham adds.
That looseness is normal until the prosthetist really gets a feel for it, Harvey says. He recommends that prosthetists who are still learning use some of the more durable check socket materials available and if possible, keep the patient in a check socket for a prolonged period of time. "That will help dial in the fit and alignment better before we proceed with definitive materials," he says. "It's a good idea because you might not know what problems to look out for initially, but they might come up throughout a week or two."
Corcoran says that to help with alignment, the attachment plate to the hip joint will often need to be modified depending on the patient's shape. The current shape of the plate is often too big, and it can position the hip joint too far distally, which will cause the patient to lose some mechanical advantage, he says. "We hack a bunch of stuff off of it," he says of the attachment plate. He then reinforces the socket with carbon fiber.
When everything is completed, the new socket designs are a big improvement, Harvey says. In previous socket designs, he says his patients could wear their sockets for two to four hours per day before they became so uncomfortable they had to doff them. In contrast, Harvey points out that "with this new socket design, they can wear it throughout the day. I don't know what other people are doing, but I can say that this has worked for me, and it works dramatically better than what I was taught in school."
Another socket design for this population was created by Jay Martin, CP, FAAOP, president and founder of Martin Bionics Innovations, Oklahoma City, Oklahoma. His design, dubbed the "bikini" of hip sockets, also takes the lightweight approach and is less than half the size and weight of the traditional bucket-style socket, he says.
Martin says that his design can more effectively capture the pelvic rotation of the user, providing greater control. The design uses a compliant iliac crest stabilizer that contours to the patient's body, instead of more commonly used rigid or semi-flexible materials, making for a more comfortable fit. The benefit of this design is that it can accommodate the user's weight fluctuations.
"One of the problems with conventional [hip disarticulation] sockets is that despite a well-crafted socket shape, that shape is largely static," Martin says. "The human body is dynamic and is constantly changing shape through its range of motion and weight loss or gain.
"We've taken a radically different approach to how these sockets are fit. Because much of the socket is now made from soft, compliant, fabric-based material, I have an easier time fitting a hip disarticulation patient than I do a transtibial patient," he says. "This socket makes the complex world of fitting hip disarticulation- and hemipelvectomy-level patients ultrasimple."
Along with a comfortable socket, new prosthetic technology to help the patient save energy when ambulating is critical to a successful fitting, Corcoran says. "The amount of energy an amputee will use at the hip level is more than twice what you and I use to walk," he says. Patients will continue to use wheelchairs or rely on crutches unless technology can help ease that burden, he adds.
"There are a lot of people with forearm crutches, but anyone who knows anything about prosthetics knows that we aren't meant to walk on our shoulders," Corcoran says. "If you use the crutches for too long, it leads to a total breakdown of the shoulders." Thankfully, he says, there is new technology that helps the patient move better and, hopefully, he or she will eventually opt solely for a prosthetic solution.
As far as the hip joint, the majority of the prosthetists we interviewed independently recommend Ottobock's Helix 3D prosthetic hip and have been encouraged after seeing it in action. The Helix 3D hip has a hydraulic stance-and-swing and mimics the human hip joint by rotating in three dimensions.
"[Ottobock] really made a huge advance over the conventional hip joint," Corcoran says. Unfortunately, he adds, the hip joint might not be available to everyone who might need it. Medicare reimbursement for it is so low that it currently would cost a prosthetist more money to fit one than the reimbursement would allow.
As far as knee joints, the prosthetists differ a bit on what has worked best for the patients they've fitted. Latham, Corcoran, and Harvey recommend the Össur POWER KNEE™. It helps reduce energy expenditure by allowing the patient to walk with a powered gait, which automates much of the knee flexion and extension and reduces the pelvic flexion and extension that would otherwise be needed to control the sagittal plane motion.
Corcoran says the POWER KNEE can come with engineering customization specifically for hip disarticulation patients and to allow adjustments for their different activity levels. "We use the POWER KNEE because of the powered flexion and extension," he says. "It reduces...huge trunk motion to get the leg to move."
With both the Helix 3D hip joint and the POWER KNEE, one of the Latham's patients, Jay Fain Jr., has walked one million steps in a year and, with a sportsspecific prosthesis, he has taken up running.
Both Harvey and Patterson have also found success fitting Ottobock's Genium and X3 knees on hip disarticulation patients. Patterson says that each has a built-in gyroscope that actually tells the knee where it is in space, which allows for a smoother and more natural gait. "It's made our job easier and, most importantly, is so much more energy efficient for the patient," he says.
Harvey agrees with this assessment. "I work with two guys from Walter Reed who are both hip disarticulation bilaterals, and with the X3 they can walk as community ambulators," he says. "That was something that was pretty much unheard of prior to [the Iraq and Afghanistan Wars]."
Getting Started with Treatment
Since patients with hip disarticulations are so rare, it can lead to problems if a patient chooses a prosthetist who is inexperienced with this type of presentation. "Most prosthetists have never done one and don't even know where to start," Sabolich says. "They're excited to try, but they don't know what they are doing, and that's where things get problematic.
Corcoran says he doesn't think a prosthetist with no experience with hip disarticulation cases should try to help the patient by him or herself. "If you try to wing it on your own by reading books, you are going to fail unless you are an extremely, extremely talented prosthetist," he says. "By and large I think you would be doing that patient a disservice by going at it without having any experience."
He recommends that inexperienced prosthetists send patients to a practitioner who does have experience with fitting hip disarticulation patients. For those who want to learn, he suggests that they subcontract an experienced prosthetist and learn from that person while the patient is being treated. The experience is necessary, Corcoran says, because even after more than 100 fittings, he's still learning what works best. "From my first hip disarticulation patient to what I do today," he says, "it has radically evolved, and how it evolves is by listening to your patient and their needs and complaints."
Looking Toward the Future
None of the prosthetists we interviewed were sure about the future technology for these patients. "Since there are so few hip disarticulate amputees as compared to other levels of amputation," Patterson says, "the demand is just not there. Unfortunately, it's not a big enough number until it's you."
Still, Patterson says he is excited about the possibilities. Recently he has begun working with Lockheed Martin Missiles and Fire Control, Orlando, Florida, to see whether exoskeletons, which have been in military use for a few years, might be a viable option for these types of patients. The exoskeleton would stand by itself, use perpetual motion, and provide the power that the patient may not have, he says. But the device must be worn on the outside of clothing, which may deter some users.
"It's not for everyone, we know that," he says. "But because hip disarticulates are limited due to the tremendous amount of energy they must use to simply walk, it may be a good solution." He hopes that new technologies and solutions come forward to help this patient population.
"The bar right now is set so low," says Jay Martin. "Conventional socket approaches for those patients are greatly missing the mark, and I'm excited to see that there are newer and better options to help those patients who have been so greatly underserved for so many years."
Maria St. Louis-Sanchez can be reached at
- Dillingham, T. R., L. E. Pezzin, and E. J. Mackenzie. 2002. Limb amputation and limb deficiency: Epidemiology and recent trends in the United States. Southern Medical Journal 95 (8):875-83.
- Shurr, D. G., T. M. Cook, J. A. Buckwalter, and R. R. Cooper. 1983. Hip disarticulation: A prosthetic follow-up. Orthotics and Prosthetics 37 (3):50-7.