June 17, 2024

Kangaroo tendons could rebuild the human knee better, stronger

Reconstructing a knee with kangaroo tissue is one step, or leap, and human trials will begin in 2024.

“I’ve always said that kangaroos are nature’s best athletes,” says orthopedic surgeon Dr Nick Hartnell, one of the study’s authors. “They really are the most impressive animals – they can jump distances of up to 12 meters (39 feet), clear a three-meter (10-m) fence and hop at 70 km/h (43 mph).

“Watching them in action, I began to wonder how much of this athletic ability had to do with the way their tendons were formed, and whether they could be used to replace torn human ligaments,” he said.

After years of research, Hartnell and his team are moving toward a human xenograft trial to repair injuries such as a torn anterior cruciate ligament (ACL).

A xenograft, in which another organ or tissue is transplanted from another species, is already a feature of surgeries such as replacing heart valves with those from donor pigs. However, biological compatibility is a huge hurdle. The team believe they have also cracked the code on how to ensure the human recipient would not reject the ‘foreign’ kangaroo tissue.

“Xenografts – using tendons from other species – have the potential to be a better option, but so far both treatments have struggled to find a suitable donor species with strong, durable tendons will not be denied,” said Dr Hartnell.

While the Australian marsupial can’t provide a human with the leaping ability of a superhuman, it does offer a promising alternative to current treatment.

In the United States, approximately 200,000 ACL tears occur each year, and up to a quarter of those require additional surgeries. The nature of the injury means that additional tissue needs to be grafted to the site of the injury. Bits taken from other parts of the patient’s body often increase pain and recovery time, while those from deceased donors and synthetic sources present other problems for surgeons.

“There is a very limited supply of these cadaveric tendons available, and unfortunately the strength is not as good as we would like, which leaves the patient with a weaker knee,” said Dr Hartnell.

“Furthermore, up to a quarter of all ACL reconstructions fail,” he said. “If that happens, or if the person has damaged two ligaments at the same time, or is injured a second time, the person is running out of options.”

Not only does the kangaroo tendon have the potential to be the best choice, but it could be sourced from other places (slaughter, food production), where this part of the animal is used for pet food, if anything.

All the research has been done on kangaroo tendons obtained from other industries, so no live animals were involved.

“They’re biologically superior as far as tendons go, and right now all that potential is being wasted because the tendons aren’t being used for anything,” Dr. Hartnell said.

The team hopes that a successful human trial will lead to the use of the kangaroo tendons in procedures around the world.

The study was published in The American Journal of Sports Medicine.

Source: Macquarie University

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