Cat gets new paws in world-first operation

Oscar the "bionic" cat has regained a spring in his step following ground-breaking surgery to fit him with a pair of prosthetic paws.

The two-and-a-half-year-old lost eight of his nine lives after his rear paws were amputated by a combine harvester as he basked in the sunshine.

Video: Oscar the bionic cat

Thanks to bioengineering work by Surrey-based neuro-orthopaedic surgeon Noel Fitzpatrick, he has gained new feet in a world-first operation.

The revolutionary design of the feet uses custom-made implants to "peg" the ankle to the foot and mimics the way in which deer antler bone grows through skin.

It has been described as a case of science copying the natural world.

Oscar's road to recovery began after his local vet from St Saviour in Jersey referred his owners, Kate and Mike Nolan, to Fitzpatrick Referrals in Eashing, near Godalming.

Following his accident last October, Oscar's life-threatening injuries had to be treated first and a course of antibiotics administered before surgery could be contemplated.

Mrs Nolan said: "We had to do a lot of soul-searching and our main concern has always been whether this operation would be in Oscar's best interests and would give him a better quality of life."

Mr Nolan said: "Through our background reading, we were aware that this sort of procedure is cutting-edge and also has an impact on human medicine, so knowledge about the way that Oscar's been treated can be carried over to human treatment going forward."

Working with a team from University College London (UCL), Irishman Dr Fitzpatrick pioneered the use of the weight-bearing prosthetic implants, combining engineering mechanics with biology.

In Oscar's case, the procedure was complicated by the fact that his feet were severed at the junction between the ankle bones and the arch of the foot.

In a three-hour operation, the veterinary surgical team inserted the pegs by drilling into one of Oscar's ankle bones in each of the back legs.

The team said it was an extremely delicate feat, which could have fractured the ankle joint before the procedure had even begun and had to be done twice.

The artificial implants, which are attached to the bone at the amputation site, were coated with hydroxyapatite, which encourages bone cells to grow onto the metal.

The skin then grows over a special "umbrella" at the end of the peg to form a seal against bacteria and potentially-fatal infections.

The peg protrudes through the bone and skin, allowing the custom-built artificial paws to then be securely attached.

Following surgery last November, the focus turned to the rehabilitation process and helping Oscar learn to walk again.

For five weeks external scaffolding was anchored to the tibia to protect the new implants until the pegs integrated into the bone and the skin grew onto the peg.

Oscar was trying to stand within a day of the operation. Despite some problems with infection, in less than four months he could stand and bear weight equally on all four limbs.

He has since been fitted with a series of prototype new paws to ensure the best possible long-term fit - and is back to his normal happy self.

Dr Fitzpatrick said: "The real revolution with Oscar is because we have put a piece of metal and flange into which skin grows into an extremely tight bone, with very narrow tolerances in the region of nanometres, rather than millimetres.

"We have then successfully managed to get the bone and skin to grow into the implant and we have developed an exoprosthesis that allows this implant to work as a see-saw on the bottom of an animal's limbs to give him effectively normal gait.

"Oscar can now run and jump about as cats should do."

Dr Fitzpatrick's bioengineering work has earned him plaudits across the world and seen him fit an artificial knee to a cat named Missy who was mown down by a hit-and-run driver.

Missy became the first cat in the world to have a replacement knee fitted after she was left with a hind leg broken in eight places.

The skin and tendons at the back of one foot had died due to crushing of the blood supply and the tissue had fallen off, leaving raw bone exposed.

In order to re-grow the tissue and cover the bone, a collagen mesh made out of pig's bladder was used. The broken bones were then placed in a scaffolding of pins until they mended.

Dr Fitzpatrick then made a knee replacement using hinged stainless steel. In 2008, he opened a £10 million facility at Eashing aiming to transform the face of modern veterinary surgery.

It is said to offer a unique mix of leading edge diagnostics and surgery with rehabilitation including physiotherapy and hydrotherapy techniques.

The work of Dr Fitzpatrick, who was born in Mountmellick in Co. Laois, will feature as part of a six-part BBC One documentary series, The Bionic Vet, starting later this month.