While this footage isn’t as exciting as I’d like it to be – I’d really prefer a big old gross close-up of a splayed knee joint – what it represents is pretty wonderful. Essentially, doctors at the Columbia University Medical Center have been able to print a knee meniscus using a degradable plastic scaffold and a protein growth system. The body then subsumes the printed object and turns the protein into a knee joint.

“At present, there’s little that orthopedists can do to regenerate a torn knee meniscus,” said study leader Jeremy Mao in a release. “Some small tears can be sewn back in place, but larger tears have to be surgically removed. While removal helps reduce pain and swelling, it leaves the knee without the natural shock absorber between the femur and tibia, which greatly increases the risk of arthritis.”

The scaffold isn’t just a plastic shell, however. It contains two human proteins, connective growth factor (CTGF) and transforming growth factor β3 (TGFβ3). The scaffold releases these factors at different times and “attracts existing stem cells from the body and induces them to form meniscal tissue.”

In sheep, the first test subjects, the meniscus regenerated in four to six weeks. The body degenerates the scaffold and whisks it away.

“We envision that personalized meniscus scaffolds, from initial MRI to 3D printing, could be completed within days,” said Dr. Mao. They will begin clinical trials once the team has raised enough cash to start printing and shipping the scaffolds to patients and their doctors.