New technology is helping amputees increase their physical activity. But it's not just people who are benefiting. Advances in surgical techniques and new designs are also getting animals that have lost limbs back on their feet.
A major problem for lower limb amputees is chafing from the socket surrounding their residual limb. This limits the amount of walking an amputee can do. Some amputees, particularly those with short residual limbs, can barely walk at all.
A new approach
An alternative method is being trialled in Australia and overseas that attaches prosthetic limbs directly to bone. It's giving amputees with short or sensitive residual limbs a chance to walk again. The technique relies on what's called osseointegration, which is the fusion of living tissue with an artificial implant.
Recipients of the treatment first have an implant screwed into the end of their bone. The implant is made of titanium as it's the only metal that bone can grow around. The bond between the implant and bone takes six months to reach full strength. A prosthetic limb is then attached to the implant.
Those who have undergone osseointegration say their prosthesis feels much more like a real limb. An amputee with a prosthetic attached to bone can feel the texture of their walking surface. They have full range of natural movement over the limb and also have better control of their prosthesis.
But the procedure has a serious risk. An incision that allows the implant to pass through the skin needs to be left open. It greatly increases the risk of infection. Concerns over infection are the main reason osseointegration is not widely used.
A cat leads the way
In the UK, Oscar the cat became a trailblazer for a new variation of the technology when a harvester severed his back legs. Veterinarian Noel Fitzpatrick heard of his case and thought Oscar was an ideal candidate for the procedure. In a three-hour operation Oscar had intraosseous transcutaneous amputation prostheses (ITAPs) inserted into what remained of his legs.
ITAPs have a special texture that allow skin to grow onto them. This allows the wound around the implant to completely heal so there is no chance of infection. The success of ITAPs in animals may pave the way for widespread use of osseointegration in people.
Meanwhile Oscar has made a great recovery from his surgery. He can do most things a normal cat can. Oscar doesn't even seem to notice his legs are unusual.
Veterinarians predict use of the technology will become common for animals missing limbs. A large number of animals reject conventional prostheses due to irritation from the socket. For some of them osseointegration is the only alternative to euthanasia.
Proceeding with caution
Uptake of the technology may be slower for humans. The long-term results of osseointegration are still largely unknown. Concerns the bone around the implant may weaken with age mean osseointegration is reserved for those who can't use normal prostheses. Doctors are hopeful that any disadvantages associated with the technology can be overcome.
Osseointegration of artificial limbs is still considered experimental by some. Those who undergo the procedure might encounter problems in the future. But they may be pioneers of a technology that provides amputees with prostheses that feel and act more like a natural part of the human body.