People with spinal disc problems can choose among several treatments in an effort to relieve their pain. They all have their advantages and disadvantages, but none can restore a problem disc to its original state. Now there's a two-step repair process which comes much closer to doing so. At the moment it has only been tested in sheep, but it has worked quite well.

Spinal discs are gel-filled sacs that help cushion the bones of the spine. When age or injury causes their filling to leak out or herniate, you're left with the equivalent of a lumpy pillow or a deflated seat cushion. If that wasn't bad enough, the material that leaked out can also put pressure on spinal nerves, causing severe pain. Two common treatments are to surgically remove the disc and any leaked material or to sew up the disc and let it cushion as best it can. Neither treatment is ideal.

The procedure only takes five or 10 minutes and can be done together with an operation to remove any debris or leaked material that is causing pain or other problems.

People have been able to have their seat or couch cushions refilled with new foam for many years, so why not try re-filling spinal discs?

To solve what is basically an engineering problem, a team of researchers from Cornell University and Cornell-Weill Medical College developed a two-step process. The first step is to refill the disc with hyaluronic acid, a thick, gooey substance with a gel-like consistency that's well suited to the task. Hyaluronic acid, or HA, is not some exotic chemical, it's found throughout the human body, including in skin and cartilage and is a common component in many joint supplements. The second step uses a special light-activated collagen gel to patch the hole. Collagen is the most abundant protein in the human body.

The procedure only takes five or 10 minutes and can be done together with an operation to remove any debris or leaked material that is causing pain or other problems.

When HA was used to repair spinal discs in sheep, the repaired discs maintained their height and shape and appeared to perform normally as the sheep went about their everyday movements for six weeks, the length of the study.

“This is really a new avenue and a whole new approach to treating people who have herniated discs,” said Lawrence Bonassar, professor of Biomedical Engineering and Mechanical and Aerospace Engineering at Cornell, who led the study. “We now have potentially a new option for them, other than walking around with a big hole in their intervertebral disc and hoping that it doesn’t re-herniate or continue to degenerate. And we can fully restore the mechanical competence of the disc.”

Before that potential can become a reality, the next step is to test the process in humans.

The study appears in Science Translational Medicine.