Doctors say three out of four people who are physically active will get a knee injury at some point, which can lead to arthritis or, in serious cases, a total joint replacement. Now, there’s a promising new technique using a surprising resource.

Doctors are performing a cutting-edge surgery: removing damaged cartilage and replacing it with healthy cartilage from a cadaver. Finding a donor, however, isn’t easy.

To be effective, the cartilage has to come from someone under the age of 13, the age when the cells are most active.

“Over time, it binds to the underlying bone of the defect and then to the cartilage surfaces around the defect, so that it forms a new cartilage layer,” said orthopedic surgeon Dr. James Gladstone.

The transplant only works in patients who still have healthy active cartilage that the donor cells can bind to. The new layer can head off future arthritis and years of pain.