Scientists working on injectable gel to grow cartilage, repair knee injuries

By Randah Griffiths

March 15, 2005 | Audrey Golightly, a senior at Utah State University and a member of the track team, has been unable to compete for over a year. She injured her knee while running and has been struggling ever since.

Golightly underwent arthroscopic knee surgery recently. She, like many other athletes, tried less invasive techniques first, but her knee did not heal. It is estimated that one in every 10 females who participate in collegiate sports will sustain a serious knee injury every year.

Like Golightly, many of these athletes are out of competition for four to five months or longer. Golightly said she knows several teammates who have also undergone arthroscopic knee surgery as a result of injuries. While some of these athletes return to compete as well as before, others never regain the ability to perform at their peak.

As a means of preventing surgery, doctors have prescribed R.I.C.E. for many years, which stands for rest, ice, compression and elevation. When these remedies do not work, surgery is the ultimate solution. Recovery from surgery can take several months of elevation, icing and physical therapy.

Torn knee cartilage (or meniscus) is the most common of knee injuries. The body does not grow new cartilage nor repair tears on its own. In arthroscopic procedures, surgeons simply remove the area of cartilage containing the tear. Until recent years, biomedical engineering professionals did not think it was possible to help the body produce cartilage.

Scientists from Harvard Medical School and Massachusetts Institute of Technology are currently developing an injectable gel which will do just that, help the body to grow cartilage.

Jason Burdick, Ph.D., a postdoctoral fellow in chemical engineering at MIT, said "The general process involves isolating cartilage or stem cells from a patient that are then combined with a liquid prepolymer solution that is injected into the area of damaged cartilage and polymerized into a hydrogel with exposure to light."

To put it more simply, patients with damaged cartilage undergo a basic arthroscopic procedure in which a cartilage sample is obtained. The patient's own cartilage is then mixed with a gel solution and injected through another arthroscopic procedure. Once in place, the area is exposed to ultraviolet light, which causes the gel to set up "like Jell-O" and stay in place. The result is instant reproduction of cartilage. Burdick says the point of the gel is not to replace cartilage, but to grow new cartilage.

This project is still being researched, but Burdick says they have found no side effects yet. He predicts the gel will be on the medical market in about five years.

It is expected that the costs will not be much higher than current arthroscopic surgery costs. "This is a relatively non-invasive procedure and it is expected that it could be performed as an out-patient procedure, so it would be less expensive than more invasive techniques," said Burdick.

The benefits of this procedure for athletes could be extreme. Scientists believe athletes would be able to return to competition much quicker than with other knee cartilage surgeries because there would be instant new cartilage.

Burdick said the gel could possibly be used in other medical fields as well. "We are collaborating with orthopedic surgeons and plastic surgeons directly on this work and the potential clinical application of injectable hydrogels. We have discussed other potential applications for ear and nose reconstruction," said Burdick.

Stan Griffiths, an orthopedic surgeon of Summit Orthopedics in Idaho Falls said, "Before an orthopedic surgeon would consider using the gel for cartilage defects, it would have to be shown in clinical trials that the gel worked better [than other techniques] in terms of pain relief, time off work, return to activity sooner, etc."

Only time will tell if this medical innovation is the answer to a growing trend in athletic knee injuries. Until then, athletes like Golightly spend months recovering from surgery. Golightly is not sure if she will ever compete in track again. She said that if the injectable gel had been an available solution to her knee injury she would have opted for it.

For further information about Burdick's research with the injectable gel, see the Jan. 10, 2005, issue of Biomacromolecules.

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