Osteoarthritis is one of the most common causes of chronic pain around the world.
Millions of people experience aching joints, stiffness, swelling, and difficulty moving as the disease slowly wears away the protective cartilage inside their joints.
The condition is especially common in older adults, but it can also affect younger people who have suffered joint injuries or carry extra weight that places stress on their knees, hips, and other joints.
For many patients, current treatments provide only temporary relief. Painkillers can reduce discomfort for a few hours, while steroid injections may help calm inflammation for a short period.
However, these treatments do not stop the disease from progressing. Over time, cartilage continues to disappear, bones begin rubbing against one another, and some patients eventually require major surgery such as knee replacement.
Now, researchers at Yale University have reported a discovery that could change how osteoarthritis is treated. Their study, published in the journal Bioactive Materials, found that the epilepsy drug lacosamide may not only reduce pain but also help repair damaged cartilage when delivered directly into the joint using a specially designed hydrogel.
The finding is significant because researchers have long searched for treatments that do more than simply mask symptoms. An ideal treatment would slow or reverse the damage occurring inside the joint while also providing pain relief.
The Yale team focused on a protein called Nav1.7. This protein acts like a gate that helps cells send electrical signals. Scientists previously believed Nav1.7 mainly existed in nerve cells involved in pain sensation. However, Yale researchers discovered that it is also highly active in chondrocytes, the specialized cells responsible for maintaining healthy cartilage.
Cartilage is the smooth tissue that cushions the ends of bones inside joints. Healthy chondrocytes constantly balance the creation of new cartilage with the removal of old tissue. In osteoarthritis, that balance is disrupted. Cartilage breaks down faster than it can be repaired, causing progressive joint damage.
The researchers found that Nav1.7 becomes overly active in osteoarthritis. This overactivity not only increases pain signals but also encourages cartilage cells to contribute to tissue destruction. In effect, a single protein appears to influence both pain and joint deterioration.
Instead of creating an entirely new drug, the researchers investigated medicines that already target sodium channels like Nav1.7. Among several candidates, lacosamide stood out. The medication is already approved to treat epilepsy and has a well-established safety record.
Laboratory experiments revealed something particularly interesting. Small amounts of lacosamide worked best. At carefully controlled doses, the drug encouraged cartilage-building activity while reducing tissue breakdown. Larger amounts were not necessarily better, suggesting that cartilage cells require a delicate balance to function properly.
The team also discovered that lacosamide stimulated the release of two protective proteins called HSP70 and midkine. These proteins help cells recover from stress, control inflammation, and support tissue repair. Together, they create an environment that favors cartilage preservation rather than destruction.
The researchers then addressed another challenge. Even if a drug works well, medications injected into the knee often leave the joint quickly because the body naturally drains fluids from the area. To solve this problem, the scientists developed a special hydrogel made from collagen.
The hydrogel remains liquid while inside a syringe but transforms into a gel once injected into the warm joint. This allows it to act as a storage reservoir, slowly releasing lacosamide over several weeks. As a result, a single injection can continue working long after administration.
In preclinical studies, one injection of the hydrogel containing lacosamide every four weeks performed better than taking the medication orally every day. The treatment slowed cartilage loss and provided long-lasting benefits inside the joint.
Analysis of the findings suggests this research could represent a major step toward disease-modifying osteoarthritis treatments. The study is especially promising because lacosamide is already approved for human use, which could shorten the path toward clinical testing.
However, the research has so far been conducted in preclinical models, meaning human trials are still needed. If future studies confirm the results, patients may eventually receive injections that both relieve pain and actively repair joint damage, reducing the need for long-term pain medication and delaying or preventing joint replacement surgery.
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The research was published in Bioactive Materials.
