Osseointegration Improves Outcomes for Amputees
Despite major upgrades in the design of prosthetic limbs, including ultra-light materials that have dramatically improved mobility and comfort for wearers, a major drawback of these devices remains: their reliance on a prosthetic socket that serves as the resting place for both the residual limb and the device. Pressure and friction in and around the socket can lead to significant pain and discomfort for amputees, and over time almost invariably induce the need for additional surgeries to ease the strain. At HSS, surgeons have been using a recently developed technology to care for limb amputees who are struggling with their prostheses—and this experience is resulting in important quality-of-life data.
The procedure, called osseointegration, avoids the need for traditional sockets against which residual limbs rest. The technique involves surgically installing a titanium rod into a patient’s remaining bone—such as the tibia or femur in the leg—which in turn attaches to a prosthesis that allows ambulation.
Although osseointegration prostheses are available to patients in the United States, HSS is one of the few medical centers to offer this particular device to patients.
“This is a disruptive technology that improves the life quality of amputees,” says S. Robert Rozbruch, MD, Chief of the Limb Lengthening and Complex Reconstruction Service and Director of the Limb Salvage and Amputation Reconstruction Center (LSARC) at HSS. “With a direct skeletal connection of the prosthetic limb, amputees report big improvements in function, comfort, balance and proprioception.”
The approach has its roots in Sweden, where the son of a dental scientist realized that his father’s use of oral implants might be translatable to limbs. “When titanium is used against the bone interface in teeth, the result is the integration of the bone into the titanium, which provides a very stable bond,” says Taylor J. Reif, MD, an orthopaedic surgeon and a member of the Limb Lengthening and Complex Reconstruction Service.
We’re seeing a tremendous improvement in functionality, in patient satisfaction, even in their connectedness with their new limb, both physically and emotionally
Patients who receive the implants enjoy several advantages over those with conventional prostheses. The devices cause less discomfort and irritation and do not require frequent refitting—a particular problem with traditional prosthetic limbs. And because the custom-fitted implants attach directly to the skeleton, patients have better balance and mobility and more control over their new limb. They report feeling more confident as a result. “We’re seeing a tremendous improvement in functionality, in patient satisfaction, even in their connectedness with their new limb, both physically and emotionally,” Dr. Rozbruch adds.
In one recent study published in JBJS Open Access in September 2021, HSS researchers reviewed the medical records of 31 men and women who underwent osseointegration procedures at HSS starting in October 2017 under compassionate use exceptions. Of those, 18 had implants in the femur and 13 had implants in the tibia.
The study, the largest to date involving patients in the United States, found that those who received the implants reported greater satisfaction with the devices than those who received conventional prostheses. These patients also experienced significant gains in scores of quality of life, as measured by physical function, mobility, pain, mood and self-image. The devices were also associated with a reduced risk for serious infections, fractures at the site of the implant and other complications.
Dr. Reif says the benefits of the implants extend well beyond the raw numbers. “The scores going up is great, but that doesn’t necessarily capture what we’re seeing in the clinic, which is smiles on people’s faces and the expressions of gratitude for how much their lives have changed. It’s totally life-altering.”
The bond between the titanium implant and the bone is strong enough that patients can rapidly resume physical activity. In some cases, they can return to vigorous, weight-bearing exercise such as running within six months to one year after the procedure.
At the end of the day, numbers and charts are nice, but as an orthopaedic surgeon, what really talks to me is when someone is able to resume the activities that used to give their life meaning
“One of the things people have talked to me about is getting back to the things they love,” Dr. Rozbruch says. He cites osseointegration patients who have returned to cycling, hiking, dancing and even motorcycling cross-country. “At the end of the day, numbers and charts are nice, but as an orthopaedic surgeon, what really talks to me is when someone is able to resume the activities that used to give their life meaning.”
For many people with conventional lower-limb prostheses, one of the first things they do at the end of the day is to take off the limb and rid themselves of the burden of the device. “Almost everybody in a socket can’t wait to get home and take off their leg. It’s exhausting, it’s heavy, it’s inefficient,” Dr. Rozbruch says. But for patients who have undergone osseointegration, the ritual is quite different. “I’ve had patients tell me they no longer take their leg off first—they take their shoe off first. I think that’s a pretty heavy statement.”
Dr. Rozbruch began performing osseointegration procedures in the early 2000s. Since 2017, he has completed more than 70 in patients ranging from teenagers to people in their 70s.
Osseointegration has been particularly appealing to younger patients, most of whom have endured catastrophic injuries to their legs in vehicular accidents or other traumatic events.
But as this technology expands and more surgeons start to employ it, I think the age that these are implanted also will expand in both directions
“The older population of patients have become accustomed to their sockets or using a wheelchair,” explains Dr. Reif. “But as this technology expands and more surgeons start to employ it, I think the age that these are implanted also will expand in both directions.”
Although some patients do experience early complications, nearly all can be managed without removing the implant. Encouragingly, while some patients develop minor infections at the stoma where the titanium post exits the skin, most of these resolve with the use of oral antibiotics.
“No implant has a perfect track record, but when you combine the functional gains that these patients are experiencing with improvements in their quality of life, a small risk of infection or fracture is acceptable to them, as well as to the orthopaedic community,” Dr. Reif says.
Among the most frustrating problems for amputees is nerve pain, which generally involves two causes: the constant pressure and squeezing triggered by the socket, which can lead to overexcited nerves in the residual limb; and so-called “phantom limb pain,” or the sensation of pain in the missing limb or extremity.
By eliminating the need for a socket, osseointegration all but eradicates residual limb pain. Yet some patients who undergo osseointegration have continued to experience phantom limb pain, prompting HSS surgeons to look for solutions. Dr. Rozbruch and his colleagues recently have been addressing the issue by pairing osseointegration with another leading-edge surgical technique called targeted muscle reinnervation, or TMR.
Although the causes of phantom limb pain aren’t entirely understood, the phenomenon appears to result from severed nerves in and around the site of the amputation that are trying, and failing, to communicate with the now-missing muscles and tissues, Dr. Rozbruch explains. Frustrated with the lack of response, the damaged nerves generate pain signals.
The combination of osseointegration and TMR has led to tremendous improvements in nerve pain
Using TMR, HSS surgeons tidy up the severed nerves (which often gather in grape-like bundles called neuromas) and reattach the stray fibers to nerve endings in the surrounding muscle. “The combination of osseointegration and TMR has led to tremendous improvements in nerve pain,” Dr. Rozbruch says. “Now those damaged nerves have a purpose and can keep themselves busy in a productive way.”
For Dr. Rozbruch, the opportunity to advance what has long been viewed as a last-ditch procedure in orthopaedic surgery has been particularly gratifying. “Amputation surgery has always had a horrible reputation as being a sort of failure,” he says. “If you couldn’t save someone’s leg, you amputated. But we are now in a new era of reinvigoration of amputation surgery here at HSS. It’s a very exciting time for surgeons and patients alike.”