To the Bone: An Advanced Approach to Attaching Prosthetics
In this episode, Joseph B. Webster, MD, discusses advances in care for people who have had amputations, including his groundbreaking work with osseointegration - bonding the connectors for prosthetics directly to a patient's bone rather than using the more traditional socket. Dr. Webster is a physical medicine and rehabilitation physician at the Department of Veterans Affairs, primarily in Richmond, Va. He is also national medical director for VA's Amputation System of Care.
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Welcome to a MossRehab Conversation, part of a continuing series of discussions with today's pioneers in physical medicine and rehabilitation from one of America's top-ranked rehab facilities. In this episode, we chat with Joseph Webster, Physical Medicine and Rehabilitation Physician at the Department of Veterans Affairs, primarily in Richmond, Virginia. He is also Nation Medical Director for VA's Amputation System of Care. First, Dr. Webster is an expert on osseointegration, bonding the connectors for prosthetics directly to a patient's bone rather than using the more traditional socket. Please tell us more about exactly what this procedure is.
Dr. Webster: Osseointegration refers to the creation of a connection between living bone and an implant that's placed inside the bone. This connection between the bone and the implant becomes solid and secure when the bone actually grows into the implant. This growth into the implant should occur without any type of foreign body reaction and should also occur without the formation of fibrous tissue between the bone and the implant.
Why is this an important development? What's its significance?
Dr. Webster: Osseointegration has been used for many years in areas such as total joint replacements. What is unique here is that osseointegration is now being used in conjunction with an implant that has a portion of the implant directly inside the bone, but then it also has another portion that is percutaneous so that part of the implant actually goes through the soft tissues and through the skin, and then it is open to the external environment. For individuals who have had an amputation, this implant can then be used to connect an artificial limb directly to the bone, and then this implant, again, goes through the skin and the soft tissues. Again what's unique and novel about this is that it now eliminates the need for a traditional socket-based suspension system for these individuals with amputations.
I would imagine that's a primary benefit of osseointegration. What are some of the other benefits of the procedure both clinically and for quality of life for the patient?
Dr. Webster: Yeah, now because the artificial limb directly connects with the bone, it avoids problems that have been traditionally associated with use of a socket-based suspension system, and those complications commonly occur with skin irritation and skin breakdown, and there can be also pain associated with use of the socket-based prothesis.
Some of the other benefits include improving a range of motion in the joint, proximal to where the artificial limb sits, and there's also improvement in the transfer of motion from the person to the artificial limb. Many individuals who have amputations have also found that use of this technology allows them to take the artificial limb on and off much easier, and all this translates into improvements in the person's ability to function and their ability to walk and perform their normal activity that they live in, and then also relates to improvements in the quality of life.
Are infections or the possibility of the implant coming loose a concern? What are the risks and potential complications?
Dr. Webster: Infection and implant loosening are still concerns with these implants. There have been a number of improvements or advances that have been made in the surgical techniques and in the implant design that have been made an attempt to mitigate these risk, but these are still risk associated with the implant. There's also a risk of fracture in the part of the bone where the implant is placed. One of the main drawbacks of this technology in the past has been the prolonged period of time it takes to rehabilitate after the implant is placed. Again, that's been mitigated a bit recently with some of the newer implant designs and protocols, but that has been a problem traditionally.
You mentioned the chance that rehabilitation could take some extra time. Is that because of the surgery involved?
Dr. Webster: It involves the surgery. Most of these implants are placed in two separate surgical procedures. The first surgical procedure involves placing the implant directly into the bone, and then the soft tissues and skin are closed, and then, typically, the second stage of the surgery is performed anywhere between six weeks and six months after that first surgery. In between that time of the first and second procedures, there can be a period where the individual can't wear an artificial limb. Then after the procedure, or after the second stage of the procedure, how quickly an individual is able to start wearing an artificial limb and how quickly they're able to start putting weight down on the artificial limb also varies depending on the type of implant that's placed. This can also result in a period of relatively prolonged rehabilitation.
Who are the best candidates, and how do you select patients for the procedure?
Dr. Webster: These implants have been used primarily in individuals with transfemoral level amputations. That's an amputation above the knee, and someone with a lower limb amputation. There have been individuals in the United States who have had this implants placed in their arm amputations as well, and primarily, that's been with amputations that have been performed above the elbow where we'll it a transfemoral level amputation.
The individuals who are the best candidates for this procedures include those individuals who had an amputation primarily as a result of traumatic injuries, and that can be traumatic injury that's combat-related or other types of traumatic injuries that result in the need for an amputation. Currently, these implants have not been used in individuals who have amputations as a result of complications from medical conditions such as diabetes and peripheral vascular disease.
That actually was my next question. How does it affect rehabilitation and functional outcomes? Are there other ways besides what you just discussed?
Dr. Webster: Just in general, as I mentioned earlier, I think the functional outcomes associated with these procedures that are associated with the use of these implants has been very positive. What we've seen is improvements in the individual's ability to walk. That includes improvements in their speed of walking, but also in their balance and with their agility with the use of an artificial limb. We've also seen gel improvements in the amount of time that a person can wear an artificial limb with the use of the implant. As I mentioned, with this implant being directly implanted into the bone, the individual no longer has difficulties wearing a socket with the skin breakdown and pain that may be associated with that, so overall, they're able to be more comfortable wearing their artificial limb, and they're able to wear their artificial limb for longer periods of time.
Well, because of that direct connection, can the patient use any prosthetic device or components or are they limited to specific devices?
Dr. Webster: This also depends to the type of implant that has been used. The implant that I'm, been using working with mostly and the implant that has been developed by the team in Utah can be used with any commercially-available external prosthetic componentry. One of the exceptions to this is the fact that these osseointegrated implants have not really been fully tested with prosthetic componentry that's able to generate forces internally, so there are a few components that are used in artificial limbs that are able to generate power internally, and again, those would be relatively contraindicative with this type of implant.
Dr. Webster, can patients swim, run, and play sports after osseointegration?
Dr. Webster: With most of the implant designs, individuals are allowed to swim or go into the water. For most of the implants, particularly during the first year after the implant is in place, individuals are encouraged to avoid any type of high-impact activity such as running, and also avoid any type of contact sports; however, with that, there are individuals who are utilizing these types of implants to perform relatively high-level activities and be able to basically resume all of their normal activity.
What about the accidental trip and fall? Can that be a problem?
Dr. Webster: That can be a problem, and the primary risk associated with that is the development of a fracture when the bone that actually contains the implant. This may require further surgery if that were to happen. The part of the implant that goes through the soft tissues and through the skin and actually connects to the artificial limb can also bend or potentially break if an individual falls, so this another potential risk associated with falls. Typically, if that happens, that component of the implant that goes through the skin and connects to the external environment can be replaced relatively easily and doesn't require further surgery.
Do you use osseointegration for both legs and arms?
Dr. Webster: The implants have been primarily utilized for individuals with leg amputations, and as I mentioned before, this is primarily for individuals who have amputations above the knee so that the implant is placed directly within the femur bone. These implants have been used for individuals with arm amputations. Those amputations, again, are primarily at the above-elbow level, and that's primarily what's being done currently within the United States.
In other countries outside of the United States, these implants have been utilized for individuals with other levels of amputations, and that also includes individuals who have had finger amputations or partial finger amputations.
You're listening to a MossRehab Conversation with Joseph Webster, Physical Medicine and Rehabilitation Physician at the Department of Veterans Affairs and National Medical Director for VA's Amputation System of Care. Dr. Webster, tell us a bit of the history of osseointegration and how we've reached the point we're at currently.
Dr. Webster: Attempts at using this type of implant system and this technology actually date back to the 1950s and the 1960s, but really, the first use of osseointegrated implants for the direct skeletal attachment of artificial limbs were performed by Dr. Rickard Branemark in Sweden in the 1990s. The types of implants and the use of this surgical procedure has really grown since that time. Another type of implant was developed by Dr. Horst Aschoff in Germany around 1999, and the design of this implant has really evolved over time. As I mentioned, use of these implants has really spread to other parts of the wold since the early 1990s.
More recently, there's been a team of researchers and clinicians both at the Department of Veterans Affairs and the University of Utah that have developed a different type of implant design. The work and research on this type of implant has taken place over the past 10 years, and that includes a human trial, which has been performed over the past couple of years with 10 subjects, and that research study is currently being completed.
The FDA approved osseointegration earlier this year for select military patients. How did that come about, and what effect has it had on your work?
Dr. Webster: Even though the procedure has been performed outside of the United States for many years, the FDA has just recently approved use of these implants within the United States, and only under certain circumstances. There have been several different pathways through the FDA that have bene utilized for introduction of these implants in the United States.
One of the types of pathways is the use of implant under a custom device designation. There is at least one implant that's been introduced in the United States via that pathway. Another implant has been approved under the FDA Humanitarian Device Exemption Protocol or Pathway, so that's another pathway of FDA approval that has occurred. The device that I've worked with most closely and that I mentioned earlier that has been developed as collaborative effort between the Department of Veterans Affairs and the University of Utah has currently undergone an FDA Early Feasibility Study, and with the completion of the Early Feasibility Study, it will allow this implant to be used with a larger number of subjects in the future but still under research protocol.
In your position as National Medical Director for VA's Amputation System of Care, you're basically on the front lines, seeing state-of-the-art care for people with amputations. What are some of the advances that you are most excited about?
Dr. Webster: This utilization of osseointegration for the direct skeletal attachment of artificial limbs, I think, is very exciting. There also continue to be advances in other types of prosthetic componentry. There's been a number of developments and advances in microprocessor technology as well as in the control systems that allow better communication both back and forth between the person and the artificial limb. This really includes ways for a person to get sensory feedback from the prosthesis and also with the way that the person's able to control the prosthesis. One of the big advances and areas of research for the future is how we can utilize the person's own thoughts and utilize brain-computer interfaces to be able to better control an artificial limb. That's one of the other real exciting new advances that I hope we'll see come to fruition in the future.
In other words, we'd be talking neural interface as well as connecting directly into the bone, putting together two current technologies to produce a third technology?
Dr. Webster: That's correct. What we'd like to be able to do in the future is have both the direct bone attachment through osseointegration, but also have some type of neural connection as well that can be done through the peripheral nervous system where you have some type of connection between the peripheral nervous system and the artificial limb, but as I mention, one of the other ways of doing that is actually directly connecting to the brain. What this allows is that if you have the direct bone attachment or the direct bone connection, that really provides a secure and stable suspension of the artificial limb, and then through the neural communications or neural connections, you can actually control the artificial limb much better than what is currently available.
Gaze into your crystal ball for a moment. What else do you see ahead for this procedure, and will it become more common?
Dr. Webster: I do believe that this procedure will become more common in the future as the technology advances and really makes this procedure more effective as well as safer for the future.
Right now, the interface between the skin and the implant really remains one of the major challenges for the future, and I believe that if, in the future, we're able to create a more stable platform between the skin and the implant that is able to remain infection-free for long periods of time, that will really, again, allow this procedure to be much more common in the future. There are a number of regenerative medicine techniques and advances in 3D printing when you're actually able to 3D print biologic tissues that will hopefully, again, provide for some solutions for this particular challenge in the future.
Well, thank you for taking the time to talk with us, Dr. Webster. Joseph Webster is a Physical Medicine and Rehabilitation Physician at the Department of Veterans Affairs. He is also National Medical Director for VA's Amputation System of Care.
Look for more conversations to come on our website at mossrehab.com/conversations. I'm Bill Fantini. Thanks for listening.