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Could we coat somebody’s bones with metal to make them superstrong?

Bones can be repaired and sometimes replaced with metal prostheses. So what’s stopping us reinforcing our skeletons? We asked expert Alisa Buchman.

Health

In addition to his super healing powers, comic book character Wolverine is best known for his indestructible metal-coated skeleton. Mutant superheroes remain the world of science fiction, but could we make our own bones stronger by grafting them with metal? Not really, says Alisa Buchman, a materials engineer at MMA Tech in Israel. “Practically it is possible to coat a bone with metal, but a living bone will not survive,” she says. “It needs the touch of its natural surroundings.” Bones need a healthy supply of blood, so they can absorb all the nutrients and oxygen they need, while expelling unwanted products like carbon dioxide, metabolic waste and acids. Coating the bone in metal would restrict this vital flow, leading to the death of the bone tissue. Current metal implants aren’t outer coatings, but stem from inside the bones. Even these come with problems, including poisoning and debris generated as the metal wears down. Implanted metals strive to be totally compatible with the body, yet still tend to suffer corrosion and cause inflammation. A problem for those without super healing abilities. Beyond these clear downsides, it may not even give us a boost in power. “Coating it with a thin layer won’t contribute to strength,” Buchman explains. “You will need a thick coating of a few millimetres, which will cause an increase in weight and will harm the freedom of movement,” she adds. The same goes for just coating the joints. “The metal must be porous and ductile, but a ductile metal will not be superstrong,” she says. And even if the process were successful the first time, it wouldn’t be a one-off procedure. “It is a big challenge to constantly adhere the coating onto the living bone,” notes Buchman. “The bone grows, cells change with time, some die, some grow,” she explains.

Fixing broken bones with metal

Through the EU-funded MP-ORIF project, Buchman investigated whether a novel material used in the aerospace industry could fix broken bones. Ageing populations around the world means the number of orthopaedic fractures are predicted to increase. Surgically implanted metals are used to hold bones together as they heal following a fracture. Conventional metals like nails, or plates are subject to wear, and the debris from this leads to inflammation, loss of bone tissue and eventually a failure of the implant itself. Buchman and her colleagues invented a new biopolymer, MP-1. It has many features which could make it compatible for use as a bone implant, including toughness, self-lubrication and resistance to wear. Following a successful investigation, the team aims to carry out clinical trials in Europe, and eventually distribute implants made from MP-1 globally. The material will find its way first into knee implants, as well as dental structures.

Potential for a novel bone composite

Could it be possible there is some unknown metal we haven’t discovered yet, which could overcome all the challenges above and let us live out our comic book fantasies? “There could be, I think it would be a kind of composite,” says Buchman. “With all the knowledge I have in adhesion and coating, I think it will be a very tough job.” Best stick to keeping your armour on the outside, like Iron Man. Click here to find out more about Alisa Buchman’s research: A material used in the aerospace industry can fix bones (https://cordis.europa.eu/article/id/430555-a-material-used-in-the-aerospace-industry-can-fix-bones).

Keywords

MP-ORIF, bones, coating, composite, implants, novel, material