Osseointegration and a microprocessor-controlled knee

The Netherlands is ahead of the curve when it comes to prosthetics, and the same goes for techniques such as osseointegration. There are many academic medical centres, like Radboudumc and Erasmus MC, in our small country, as well as specialised teams of surgeons, physiotherapists, occupational therapists, psychologists and orthopedic consultants who work closely together. “It’s a truly unique situation”, says Ottobock’s Tom Bernard, who is in charge of Technical Sales Prosthetics. "Because these specialists complement each other so well and because they are willing to keep training and learning, osseointegration technologies have developed enormously. In fact, the Netherlands is one of the top 5 countries for osseointegration.”

Click-on prosthetics

Osseointegration involves attaching a metal pin to the bone in one’s residual limb, after which the artificial limb can be clicked into place through an opening in the skin. That’s why osseointegrated limb replacements are also known as click-on prosthetics. “In the past, artificial limbs would be connected to the body through a socket that fits around the residual limb”, Tom explains. “The socket, in turn, would be attached to the artificial limb itself. In osseointegration, which was first performed in the Netherlands about 10 years ago, the artificial limb is connected directly to a person’s skeleton, eliminating the need for a socket altogether.

This has lots of advantages”, Tom continues. “Prosthetic sockets are often a source of problems for amputees. They can be uncomfortable at times, for example when sitting down, and sweat can often lead to skin problems, which can result in infections. All in all, this means that amputees with sockets may run into mobility issues. With osseointegration, you remove this inconvenience in one fell swoop. Besides, osseointegrated artificial limbs are a whole lot easier to put on.”

Bone stability

Unfortunately, not everyone is eligible for osseointegration. Tom explains: “It really depends on the person. For example, the bone has to be sufficiently stable and must be able to withstand the impact. The length of the bone also matters: the longer the bone, the easier the implantation process will be. In people with through-the-knee amputations, for instance, it is a lot more difficult to implant a pin into the bone. In people who have had a knee disarticulation, on the other hand, the knee can be removed to pave the way for osseointegration. Lifestyle is a key factor in determining whether an amputee is eligible for osseointegration, and there are certain essential criteria that they must meet. For instance, your weight - or BMI - has to be healthy, and smokers are also less likely to be eligible, as blood flow through the limb has to be optimal. That’s also why people with diabetes are less likely to be eligible. Because you’re essentially leaving part of the body open to the outside world, residual limb hygiene has to be optimal. Seeing as candidates have to meet these criteria, we always discuss whether someone is eligible for osseointegration with the entire treatment team.”

Microprocessor-controlled knee

The developments surrounding osseointegration are not the only piece of evidence demonstrating how far ahead of the curve we are in the Netherlands. Microprocessor-controlled knees – a high-tech knee system that responds automatically to certain situations and actions and thus allows for more natural movement – is also becoming increasingly common. “At Ottobock, we strive for safety and comfort, which is why we’re big fans of this system.” Tom is adamant about the benefits of osseointegration when combined with a microprocessor-controlled knee: “They’re an excellent combination. Our goal is always to make artificial limbs that are as safe and as comfortable as possible.” Still, not everyone with an osseointegrated limb will also get a microprocessed-controlled knee right away. Often, amputees have to continue using their existing equipment with the new implant. If they had a socket first, the socket will be modified, rather than being replaced by a microprocessor-controlled knee or C-leg.

“It’s an understandable approach”, Tom admits. "All in all, osseointegration surgery can cost anywhere between 30,000 and 40,000 euros, and the accompanying click-on adapter will set you back another 6,500 euros. A microprocessor-controlled knee will easily cost 18,000 to 20,000 euros. It’s a lot of money and health insurers do not always cover the costs. As a result, amputees getting an osseointegrated limb will often have a click-on prosthetic first. By the time they need a replacement part or a new artificial limb, a request will be put in for a microprocessor-controlled knee. It’s a gradual process.”

Natural gait

It is clear to see that osseointegration has myriad advantages, especially when it’s combined with a microprocessor-controlled knee. “First of all, it enables a very natural gait, because the amputee will move around their weight in exactly the right way. Whereas amputees with an osseointegrated limb will feel vibrations with every step they take, a microprocessor-controlled knee would absorb the shock of their heel striking the floor, making it more comfortable and safer to move around. The whole body benefits from a microprocessor-controlled knee. You could compare it to the effect of installing a door closer on a door. A door without one will slam shut when there’s a draft, whereas the door closer would cause it to close more gradually. Microprocessor-controlled knees do much the same thing.”

Despite the many benefits of osseointegration, Tom stresses that amputees should be well aware of the risks, too. “Young people who want to continue to exercise or play sports at a high level should consider whether osseointegration has real added value for them. If you want to be a sprinter or a long jumper, you might want to think twice. In some sports, having a pin implanted into your leg is not a particularly wise move, and in some cases it might not even be possible. The bone may rupture on impact, and the implant would have to be removed. If you’re a keen cyclist and fall off your bike every now and again, it’s important to remember that falls can be very dangerous if you have an osseointegrated limb. If you don’t have any skin problems and live a very active lifestyle, a traditional socket might simply be the best solution. Whether or not osseointegration is the best choice will differ from one person to the next.”