Direct Connections

As implant options expand, prosthetists should prepare to see more patients who have undergone osseointegration

By CHRISTINE UMBRELL

Eric Mollaret, a transfemoral amputee and recipient of the OPRA™ Implant System, enjoys the ordinary, simple and everyday freedoms that many take for granted.

PHOTO: Integrum NEED TO KNOW • Approximately 2,000 individuals worldwide, and 500 who live in the United States, have undergone osseointegration (OI) surgery to attach a prosthesis via implant.

• The OI market is expected to expand in the United States: The

OPRA Implant system received FDA approval for individuals with transfemoral amputation in late 2020; the VA began offering the OPRA system for some patients in January 2022; and several other implants are currently in FDA trials and expected to hit the market soon.

• OI is not for everyone, but it can be life-changing for a segment of the limb loss population, including some for whom sockets are problematic.

• Successful OI journeys rely on a multidisciplinary team approach—the surgical team focuses on the implant and stoma, while the prosthetist fits, aligns, and maintains every component from the abutment distally.

• Only 0.03% of the limb loss population currently has implants—so prosthetists will continue to design socket-suspended prostheses for the vast majority of their patients.

MORE THAN 500 individuals with limb loss residing in the United States have undergone osseointegration (OI) surgery to achieve direct skeletal attachment of a prosthesis to their residual limb via implant, according to estimates from the National Association for the Advancement of Orthotics and Prosthetics (NAAOP). This number is expected to increase at a fast pace as more implants receive recognition by the Food and Drug Administration (FDA). As awareness of and demand for OI grows, more prosthetists will need to effectively treat this patient population.

The procedure can be both lifechanging and transformative for a segment of the limb loss population, many of whom cannot comfortably wear sockets. “We are reestablishing a person’s normal gait symmetry, instead of accommodating a person’s loss of a limb,” explains Jason Stoneback, MD, chief of the Orthopedic Trauma and Fracture Surgery Service and director of the University of Colorado Hospital Limb Restoration Osseointegration Team.

Stoneback has performed more than 60 primary OI surgeries and more than 100 OI-related surgeries as part of a multidisciplinary team at the University of Colorado over the past five years, and he has watched most patients return to a more normal gait using a prosthesis without a socket. He explains it this way: “A high-level transfemoral amputee typically gets flexion contractures and abduction contractures” when using a traditional socket, because using a socket “is not a normal way for a person to hold their limb,” Stoneback says. Prosthetists typically make a socket “to fit over the deformity to allow that person to bear weight.”

Stoneback meets with a transfemoral patient after his osseointegration surgery.

With osseointegration, “instead of accommodating a deformity, we underaccommodate it to stretch out contractures and reestablish normal anatomic alignment,” Stoneback explains. “We’re reharnessing their normal skeletal alignment and making them bionic—returning them to a normalized symmetric gait pattern.”

Jason Stoneback, MD

Benefits and Limitations

Two types of implant devices can be used in OI procedures. Screw-fixation implants utilize a threaded cylindrical design and are applied through a two-stage surgery. Press-fit implants are similar to common artificial knee and hip joints and can be performed in a single-stage surgery.

OI made its American debut in late 2013, when a nurse from the Las Vegas area became the first patient to undergo OI surgery in the United States. For the next several years, the procedures were limited due to FDA device restrictions. Many early surgeries were performed as part of clinical trials approved by are expected to hit the market soon. Of course, many U.S. patients continue to undergo OI surgeries via HDE and by traveling overseas.

Stoneback regularly performs surgeries with press-fit implants under the FDA custom device exemption and with the OPRA implant under FDA’s full market approval for transfemoral patients. “I do both so I can offer the best option for each patient, depending on their anatomy,” he says. His team also sees patients suffering from complications from OI surgeries initially performed elsewhere within the U.S. and abroad, including patients with infections or soft tissue issues. “As our team has gained more experience, we have developed the ability to take on extremely complicated cases,” including individuals who need bone-grafting or lengthening procedures before OI.

the FDA through an Investigational Device Exemption to collect safety and effectiveness data. Some other patients received OI surgeries under the Humanitarian Device Exemption (HDE) that allows medical devices that are not otherwise FDA-approved for marketing to be used in limited circumstances without requiring evidence of effectiveness. In addition, more than 200 Americans traveled to Australia or European countries to have the procedure.

But OI is gaining in popularity, and the market is “about to explode in the United States,” according to Jeffrey Cain, MD, a family doctor at the University of Colorado and an Amputee Coalition board member who has OI implants in both legs. In late 2020, the FDA approved the Osseointegrated Prosthesis for the Rehabilitation of Amputees (OPRA™) Implant System, a screw-fit device, for individuals with above-knee amputation. In January 2022, the Veterans Health Administration began offering the OPRA Implant System for use in some patients with transfemoral amputation—for example, those who have experienced amputation due to trauma or cancer and for those who have or are anticipated to have rehabilitation problems with a socket-suspended prosthesis. Currently, several other press-fit implants are in FDA trials and Stoneback and his team at University of Colorado evaluate a transfemoral OI patient.

So why is OI such an important advancement? OI offers several advantages for the individuals who qualify for the procedure, according to Christopher Hoyt, CP, director of osseointegration at Rise Prosthetics and lead prosthetist on the University of Colorado Hospital Limb Restoration Osseointegration Team. Those benefits include “optimal skeletal control, anatomical alignment, repeatability in donning, and zero pistoning—goals we strive for in every socket fitting but cannot always achieve,” Hoyt says. Additional advantages may include no range-of-motion limitation, sitting/ Jeffrey Cain, MD

cycling comfort, more natural heat dissipation, elimination of friction and perspiration issues, ability to wear a shower prosthesis to wash and maintain stoma hygiene, and elimination of follow-up appointments due to limb volume changes, says Hoyt. In addition, most OI patients gain osseoperception—where the prosthesis “feels” more like part of the body, aiding in proprioception and balance.

For above-knee patients, “studies have shown patients with OI wear their prostheses longer, walk further, and use less energy compared to traditional sockets, because OI improves biomechanics and allows use of hip muscles in a more anatomic way,” says Cain.

The Right Candidate

While OI is a viable solution for some limb loss patients, it’s not for everyone. Prosthetists should understand who might be—and who won’t be—a good candidate.

Research Demonstrates Benefits of Osseointegration

While still in its infancy, osseointegration—and its advantages—are starting to be documented:

• Researchers at the Osseointegration Research Center at the

University of Colorado Hospital recently conducted a case series study of four patients with lower-limb amputation who were scheduled to undergo unilateral transfemoral prosthesis osseointegration (OI). Each patient received a press-fit implant that was implanted by the same surgeon,

Jason Stoneback, MD, in two stages. At 12 months post-OI,

Stoneback’s team found that, compared to baseline with socket prostheses, patients with osseointegrated prostheses demonstrated reduced lateral trunk bending, pelvic obliquity, and rotation toward the amputated limb during the standto-sit task. This was accompanied by increased amputated limb hip flexor, abductor, and rotator muscle forces. In other words, improved lumbopelvic movement patterns and stabilizing muscle forces when using an osseointegrated prosthesis indicate that the implanted prosthesis type likely reduces the risk of the development and/or progression of overuse injuries, such as low back pain and osteoarthritis.

The researchers attributed the increased muscle hip muscle forces to the increased load transmission between the osseointegrated prosthesis and residual limb. The study was published in August in Clinical Biomechanics.

• In a study published in June in European Journal of Trauma and Emergency Surgery, researchers conducted a retrospective comprehensive analysis between February 2017 and December 2018 of 36 patients with socket-suspended prostheses and 33 patients treated with transcutaneous osseointegrated prosthetic systems. They concluded that the OI patients showed

“significantly higher scores for mobility and satisfaction.” • An April 2022 study by researchers at the University of Sydney and the Osseointegration Group of Australia (OGA) analyzed outcomes of 93 patients with transfemoral amputation and press-fit osseointegrated prostheses treated in several facilities worldwide. The researchers found that all 93 patients continue to use their OI-attached prosthesis, with outcome measures indicating significant improvements—although several adverse events, including 19 implant revisions, eight periprosthetic fractures, and 43 surgical debridements, were reported. Results were published in Orthopaedic Proceedings from the British Limb Reconstruction Society Annual Meeting.

• In an earlier study, a research team at OGA studied a cohort of 10 patients with diabetes who underwent osseointegration, six of whom relied on a wheelchair before OI. “Any surgery for a diabetic is risky and OI is no different; these patients are not free of complications, but they are all doing very well, living full active, mobile lives,” except for one subject who died for unrelated reasons, says Nikki Grace-Strader, director of North American operations at OGA. “The improved quality of life and mobility may also in turn provide a protective effect against their underlying diabetic conditions.” The study was conducted in 2017 and is available at https://doi. org/10.1016/j.apmr.2017.08.025.

“Patients that stand to benefit most from OI are those with challenging residual limbs, such as short transfemoral limbs, large-volume limbs where skeletal control is poor, and limbs that cannot tolerate a socket interface due to poor skin integrity or particular nerve conditions,” says Hoyt. “If a patient goes to a prosthetist who creates a well-fitting socket, and the patient continues to have problems wearing a prosthesis, then that patient may be a candidate for OI.” But before moving forward with OI, “multiple other health and psychological-related factors should be considered”—which is why patients at University of Colorado work closely with a multidisciplinary team before being approved for surgery.

Amputees with extremely short residual limbs, patients who weigh more than 275 pounds, and patients involved in high-impact activities are not good candidates for OI, according to Hoyt. “We highly recommend that high-impact activities be discouraged” after OI surgery, due to risk of fracture.

“Patients will need to be able to accept some limits if they are going to be good candidates for implant procedures,” adds Cain who says that patients are advised to avoid hightorque, high-impact activities, such as running or skiing.

Candidates also should understand all of the risks associated with the surgery, which may include skin penetration, site/stoma pain, periimplant fractures, infection, breakage, risk of need for removal, and more, says Stoneback. And some people with certain medical conditions simply cannot handle the surgery. “We are still in the stages of figuring out what medical conditions may prevent patients from having an optimal outcome,” Stoneback says.

Cain traveled to Australia nearly six years ago for OI surgery on both legs. Cain's X-rays postosseointegration, and showing alignment

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Prosthetist Participation

Prosthetists need to be educated on OI, says Cain. “Your patients are going to start asking about osseointegration,” he says. “You’ll need to be able to explain the implant surgery, who is a good candidate, and the potential risks and benefits.”

Being fit with the appropriate prosthesis post-OI is extremely important, says Cain, who notes that the prosthetist’s contribution to the care team is often under-recognized. While silicone and gel liners allow a little room for play, “OI alignment is even more critical than with traditional sockets. Even minor misalignment after OI can cause joint problems and pain,” says Cain.

Hoyt agrees that dynamic alignment is key. As the prosthetist on University of Colorado’s multidisciplinary team, he works closely with both OI patients—who travel from all over the country—and their local prosthetists to ensure patients’ prosthetic needs are met. “The surgical team deals with the

Christopher Hoyt, CP

Hoyt uses FaceTime with a prosthetist to explain how to adjust and tighten bone-anchored prostheses. A patient who has undergone osseointegration at the University of Colorado engages in 3D motion capture analysis.

implant and stoma, while the prosthetist fits, aligns, and maintains every component from the abutment distally,” he explains.

Presurgery, Hoyt often discusses current device options with the patient’s local prosthetist and ensures the patient arrives with components that will work well post-OI, such as a microprocessor knee and a foot with a torque absorber. Postsurgery, “the prosthetist’s role can now focus on dynamic alignment, optimal componentry, and maintenance,” rather than socket-fitting hand skills, he says.

After completing the three-week intensive rehab period at University of Colorado postsurgery, patients typically return home using bilateral forearm crutches for another three to four weeks, says Hoyt. As patients become more proficient at walking postsurgery, local prosthetists “become dynamic alignment specialists.” Hoyt frequently uses FaceTime or calls patients’ local prosthetists to ensure an optimal continuum of care, and to discuss the maintenance and adjustability of connectors for OI patients. While some prosthetists are nervous when seeing their first OI patients, treating these patients “is often easier than they expect,” he says.

It’s important that prosthetists understand componentry needs post-OI. One of the downsides of osseoperception is that some patients become hypersensitive, and may not be able to tolerate bumps and vibrations—particularly in the first few weeks postsurgery. Prosthetists should “choose optimal componentry that won’t aggravate those with enhanced osseoperception,” Hoyt says.

As an OI patient, Cain says the direct bone connection now allows him to feel “every rub or tweak or toe-off from my prostheses. Componentry choice matters a lot, and it is important to include torque and shock absorption after OI.”

Similar to patients with socketsuspended prostheses, OI patients view their prosthetist as the go-to person for questions, concerns, and emergency adverse events, says Hoyt. “We are rare, long-term healthcare providers who take the time to listen, problem-solve, and make ourselves available at some of the craziest hours.”

Cain advises prosthetists interested in treating OI patients to do their homework now to prepare for the influx of patients that is coming. “If you are going to include care of patients post-OI,” he says, “you will need to take classes to learn the different methods of alignment and considerations for componentry.”

Patient Perspectives

Osseointegration may not be for everyone, but “it can be transformative for the right patients with lower-limb loss,” says Jeffrey Cain, MD, a family doctor at the University of Colorado who underwent the procedure on both legs nearly six years ago. After losing both lower limbs from an accident 25 years ago, Cain successfully used traditional prostheses with sockets for nearly two decades—but then nerve compression issues led to pain with his prosthetic devices that limited him to only a few minutes of standing or a block of walking. Seeking a solution, Cain spent two years consulting multiple prosthetists, orthopedic surgeons, and rehabilitation physicians without success. He tested dozens of sockets and liners, tried different suspension systems, physical therapy, and nerve injections, and even acupuncture and Chinese herbs—all to no avail. Rather than resign himself to a life in a wheelchair, he discovered osseointegration. After conducting his own review of osseointegration research and a risk/benefit analysis, Cain traveled to Australia to undergo the procedure with the Osseointegration Group of Australia (OGA). He had single-stage surgery with press-fit implants. His surgical recovery included complications—he was among Jeffrey Cain, MD the 30% of patients who experience a skin infection and the 10% who develop a deep tissue infection and required surgical debridement, he says. But he eventually healed and was able to be fit with prostheses.

How did Cain’s life change post-implant surgery? His wheelchair is now gathering dust. He is no longer in constant pain; no longer searches out a place to sit down every time he enters a room; doesn’t have to carry extra sleeves, liners, and lotion everywhere he goes; and with osseoperception can even “feel the snow crunch under my feet.”

Like Cain, Nikki Grace-Strader, the 2022 Breece Fellow at the National Association for the Advancement of Orthotics and Prosthetics (NAAOP) and director of North American operations at OGA, calls her osseointegration journey transformative. Grace-Strader, who also has a spinal cord injury, lost her leg above the knee six years ago. She was hopeful that her first traditional prosthesis would return her to full mobility—but that was not the case. “You need to have movement in the lumbar spine to use socket technology [effectively], and I don’t,” she says. Using a socket, she could manage a maximum of 2,000 steps on her best days—and strategically planned out each step to maximize her movements.

After conducting some research and learning about OI, Grace-Strader traveled to Australia to undergo the procedure at OGA.

“It was lifechanging,” she says. Now, she walks more than 5 miles most days, which “wouldn’t have been possible without OI,” and takes part in other activities she had given up before her surgery. Since her OI procedure, she has spent a great deal of time with her prosthetist, particularly because alignment is so critical with implants. “If I am a millimeter out of alignment, I feel it in my neck and teeth—it is like walking around with a rock in your shoe, or wearing shoes with different heel heights, and you are very sore by the end of the day,” Grace-Strader says. She also notes that, because she is more active, she needs to replace her prosthetic foot much more frequently—about once a year.

“OI is not the right answer for every amputee,” says Grace-Strader, “but it should be an option—and amputees and clinicians should be able to make informed decisions.” Grace-Strader recently took part in NAAOP’s Hill Day, visiting members of Congress to advocate for the Medicare O&P Patient-Centered Care Act, S 2556/HB 1990—and dropping off one-page issue briefs to educate lawmakers about OI. “We just want to get everyone to start thinking about OI,” to set a foundation for the coming years when more consumers choose to undergo the procedure and will want health insurance companies to reimburse for implants.

Nikki Grace-Strader

Christopher Hoyt, CP, works with a patient who has undergone OI. The Future of OI

As OI gains ground in the United States, more people may be able to successfully use their prostheses. However, ensuring coverage by payors is challenging.

“As pioneers in OI fitting, we must also be pioneers in billing/ reimbursement,” says Hoyt. “One would think that if the surgical procedure is covered by the insurer, then the specialized OI connector would be covered as well. Unfortunately, Medicare has approved some; denied others; and partially paid for the rest.” Hoyt also hopes that as more research regarding the safety of the procedure is completed, more insurers will be willing to reimburse.

Hoyt and Stoneback can see a future where there are many more implant choices, and where patients who are not good candidates for sockets may receive an OI surgery as their primary amputation surgery—including individuals with very high transfemoral amputations and those with very large-tissue-volume residual limbs, as well as patients with transhumeral amputations.

In the meantime, creating wellfitting sockets remains a priority for prosthetists. “Osseointegration in the U.S. is in its infancy, limited by the number of implants available as well as third-party payor reimbursement,” explains Hoyt. He estimates there are approximately 2,000 OI patients, in the world, “which is only 0.03% of the amputee population,” he says. “That means 99.97% of patients are still using sockets. That number will increase as we demonstrate that benefits outweigh the risks, but there will still be plenty of socket patients for prosthetists to see.

“Osseointegration is here to stay, but limited in the number of candidates,” Hoyt concludes. He encourages prosthetists to “focus on quality, intelligent design for your socket-suspended clients, and be knowledgeable and prepared to care for the OI patients you encounter.”

Christine Umbrell is a contributing writer to O&P Almanac. Reach her at cumbrell@contentcommunicators.com.

Hear More on OI at the Assembly

Don’t miss the session “Osseointegration in the United States—Prosthetic Implications for Today and Tomorrow,” which will take place Thursday, September 29, at 10:30 a.m. during the 2022 AOPA National Assembly. Jason Stoneback, MD; Christopher Hoyt, CP; and Jeffrey Cain, MD, will share updates on osseointegration and discuss the critically important role of the prosthetist in the success of the patient after osseointegration.