Imagine a simple shot that could fix a creaky, painful joint in just a few weeks — no surgery, no replacement. That future might be closer than you think, thanks to a team of researchers in Colorado.

Scientists at the University of Colorado Boulder, Colorado State University, and CU Anschutz have developed two new treatments that helped animals with osteoarthritis heal in four to eight weeks. Their joints actually bounced back to a healthy state.

Osteoarthritis is the third most common disease in the United States, affecting roughly one in six people over age 30 worldwide. It happens when cartilage — the rubbery tissue that cushions joints — breaks down. Bones start grinding against each other, making movement painful. Right now, there's no cure. Patients can either manage the pain or get their joint replaced through major surgery.

"Our goal is not just to treat pain and halt progression, but to end this disease," said Stephanie Bryant, a professor of chemical and biological engineering at CU Boulder who led the research.

The Colorado team created two approaches. The first is a single injection that uses an existing drug already approved by the Food and Drug Administration. The researchers designed a tiny particle system that slowly releases the medicine into the joint over months, helping damaged tissue repair itself. The second treatment is a biomaterial kit for people with bigger problems — holes in their cartilage or bone. Doctors inject a cocktail of engineered proteins into the joint, then "cure" it in place like a patch. The proteins call in the body's own repair cells to fill in the gap.

When the researchers tested the injection on animals with arthritic joints and injuries, the joints returned to a healthy state within four to eight weeks. They also saw "full regeneration and repair of the defect" when patching holes in bone or cartilage. Even in human cells taken from patients undergoing joint replacements, the therapies showed a clear regenerative effect.

Bryant and her team received funding through NITRO — short for Novel Innovations for Tissue Regeneration in Osteoarthritis — a $30 million project supported by ARPA-H, a federal health innovation agency. "In two years, we were able to go from a moonshot idea to developing these therapies to demonstrating that they reverse osteoarthritis in animals," Bryant said.

The team plans to publish their animal findings in a peer-reviewed journal later this year and has formed a company to help bring the treatments to market. If everything goes well, Bryant expects human clinical trials could begin in as little as 18 months.

"This could be a real game-changer for patients," Bryant said. "At the moment, the options for many patients are either a massive, expensive surgery or nothing. There's not a lot in between." She and Dr. Evalina Burger, chair of orthopedics at CU Anschutz, imagine a day when someone in the early stages of joint trouble could get a single affordable shot and stay active for years.