Millions of people the world over get hip or knee replacements, each year, says Anne Trafton, of the MIT News Office. She’s reporting on a breakthrough researchers at the university have made in creating a compound to replace the “bone glue” that is currently in use. The new coating, currently being tested in animals, creates a more natural fit between the artificial components of implants and natural biological parts of the leg or hip.
Hip and knee replacements have skyrocketed since their introduction in the 1970’s as prior to that, people who developed osteoarthritis, were most often relegated to wheelchairs. Osteoarthritis, according to the National Library’s PubMed Health, is a joint condition that occurs when cartilage wears down over time leaving bones to connect directly. In its initial phase, patients experience pain and stiffness. As it progress, it eventually becomes impossible to use the joints that are affected.
Trafton writes that in approximately 17 percent of hip and knee replacements, the bone glue that is used to connect the implant to bone in the knee crystallizes and breaks, necessitating new replacement surgery. The new material created by the team at the university binds the two together in a completely new way.
Bone glue works very nearly the same as any other glue, it simply binds to objects together. Because most failures occur where the implants connect with bone, the new research focused on that part of the implant process. The new coating causes the growth of new bone cells which then bind with the coating material itself, creating a far stronger bond than bone glue, and one that is less likely to be rejected or break down in the body, leading to failure.
The new material, made from calcium, which is of course what bones are made of, and other binding ingredients, is applied to the plastic portion of the implant (the actual joint is made of steel to allow for rotation, which occurs when a person walks) and to the bone that has been cut when the natural knee or hip was removed. When pressed together, the two bond instantly and over time, as new cells grow, that bond grows ever stronger. Trafton reports that new bone growth typically takes just two to three weeks.
Thus far, trials with animals have shown that the new material can lower failure rates down to almost zero, though more testing will of course have to be done to make sure there are no adverse side-effects. If all goes well, it’s likely the new coating will be available to patients as soon as a year or two.
Trafton says that new coating could also be used to help repair broken bones or teeth or as a new way to affix tooth implants.