For people living with osteoarthritis, the problem is rarely just pain. It is pain that returns after tablets wear off. It is stiffness that reshapes morning routines. It is the slow loss of trust in a knee, hip, hand, or shoulder.

Current treatments can help many patients get through the day, yet most do not change the underlying course of the disease. A new Yale-led preclinical study suggests that a familiar medicine, delivered in an unfamiliar way, may point towards a more ambitious goal — easing pain while protecting cartilage.

The study, published in Bioactive Materials in 2026, examined lacosamide, a medicine already approved for epilepsy, as a potential treatment for osteoarthritis. Researchers found that the drug appeared to reduce joint pain and limit cartilage damage in laboratory and preclinical models.

The effect became stronger when lacosamide was packed into a specialised collagen-based hydrogel and injected directly into the joint, where it could be released slowly over several weeks.

That combination matters. Osteoarthritis has long been treated as a condition of wear, age, weight, and mechanical stress. Those factors are real, yet they are not the whole story. The disease is also biological. Inside cartilage, cells known as chondrocytes work constantly to maintain the tissue that cushions joints. They produce cartilage-building proteins. They clear damaged material. They respond to inflammation, injury, and changes in the joint environment. In osteoarthritis, that balance shifts. Breakdown begins to outpace repair. Cartilage thins. The joint becomes inflamed. Movement becomes harder. Pain becomes persistent.

For many patients, treatment options remain limited. Paracetamol, non-steroidal anti-inflammatory drugs, topical gels, physiotherapy, weight management, braces, and steroid injections can be useful. Some improve function. Some reduce flares. None has been proven to reliably rebuild damaged cartilage or stop osteoarthritis from advancing in the broad patient population.

When disease progresses far enough, joint replacement may become the most effective option. It can be life-changing, but it is major surgery. It is not suitable for everyone, nor is it the early answer patients hope for.

The Yale study focuses on a protein called Nav1.7, a sodium channel. Sodium channels act as tiny gates on cell membranes, helping control the movement of charged particles. In nerves, this movement helps create electrical signals. Nav1.7 is well known in pain research because it plays a major role in how pain messages travel from the body to the brain. People with certain Nav1.7 mutations can develop unusual pain disorders. Others with rare loss-of-function mutations may feel little or no pain.

What makes the new work especially interesting is the location of the target. Researchers reported that Nav1.7 is not only relevant to pain nerves. It is also active in chondrocytes, the cells responsible for maintaining cartilage. In healthy joints, this channel appears to stay relatively controlled. In osteoarthritis, it becomes more active. That overactivity may contribute to two linked problems, an increased pain signalling and accelerated cartilage breakdown.

This gives Nav1.7 unusual appeal as a treatment target. Many osteoarthritis medicines focus on symptoms. Others are being investigated for structural protection. A target that appears to sit at the crossroads of pain and cartilage biology could, in theory, do both. The researchers describe Nav1.7 as a dual-acting target because blocking it may calm pain pathways while also encouraging cartilage cells to behave in a more protective way.

The team did not begin by inventing a completely new medicine. Instead, scientists looked at existing sodium channel blockers. That choice is practical. New drug development is expensive, slow, and risky. Repurposing an approved medicine can sometimes shorten the path towards human testing, because basic safety information already exists. Lacosamide stood out during testing because it produced strong effects at low concentrations. It also has a better-established safety profile than some older medicines in its class.

The results were not as simple as “more drug, more benefit”. The study found an optimal range. At low, carefully controlled concentrations, lacosamide encouraged cartilage-supporting activity and reduced destructive signals. At doses that were too low or too high, the benefit weakened. That pattern is important. It suggests that the biology of cartilage repair is finely balanced. Pushing the system too little may do nothing. Pushing it too far may blunt the desired effect.

Researchers also identified possible mechanisms behind the protective response. Lacosamide appeared to stimulate the release of HSP70 and midkine, two signalling proteins linked with stress response, tissue repair, inflammation control, and cell survival. In simple terms, these proteins may help create a healthier neighbourhood inside the joint. They do not merely affect one cell in isolation. They may influence surrounding tissue, giving cartilage a better chance to resist degeneration.

The delivery method may be just as important as the drug. Lacosamide can be taken by mouth, yet oral treatment sends medicine throughout the body. That can be helpful for epilepsy. It is less ideal when the intended target is one painful joint. Systemic exposure can increase the chance of side effects. It may also mean that only a limited amount of medicine reaches the cartilage at the right concentration.

Injecting medicine directly into a joint can solve part of that problem. The drug goes where it is needed. The dose can be local. The rest of the body may be exposed to less of it. But joints, especially knees, do not hold injected liquids for long. Fluid can be cleared within hours or days. That creates a familiar challenge in musculoskeletal medicine. How do you keep a treatment inside a moving, fluid-filled, biologically active space long enough to matter?

The answer tested in this study was a thermoresponsive hydrogel made from collagen II, a key component of cartilage. Thermoresponsive means it changes behaviour with temperature. In a cool syringe, the material remains liquid enough to inject. Once inside the warm joint, it becomes more gel-like. The hydrogel then acts as a depot, holding lacosamide in place and releasing it gradually.

This is where the work becomes more than a drug story. It is a delivery story. A medicine that might otherwise disappear quickly from the joint is turned into a longer-acting local therapy.

In the preclinical tests described, a single injection of lacosamide-loaded hydrogel every four weeks performed better at protecting cartilage than daily oral lacosamide. That finding supports a broader idea now shaping many areas of medicine. Where a drug goes, how long it stays there, and how steadily it is released can be as important as the drug itself.

For patients, the appeal is clear. A treatment that could be injected periodically, act locally, reduce pain, and slow cartilage loss would fill a major gap. It could reduce reliance on repeated steroid injections, long-term painkillers, or opioids.

It could also delay, or perhaps prevent, the need for joint replacement in some patients. Those are possibilities, not proven clinical outcomes. The study remains preclinical. Human osteoarthritis is complex. Animal and laboratory findings do not always translate into real-world benefit.

Still, the work is notable because it brings together several promising features. The drug is already approved for another use. The target has a strong connection to pain biology. The same target appears to influence cartilage cells. The hydrogel addresses a known delivery problem. The treatment interval tested, about once every four weeks, would be practical if later studies confirm safety and benefit in people.

Caution is needed. Lacosamide is not currently approved as a disease-modifying osteoarthritis treatment. Patients should not take it for joint pain unless prescribed by a qualified clinician for an approved or carefully supervised reason. The dose needed inside a joint may not match the dose used by mouth for neurological conditions. The optimal range seen in the study also raises a key clinical issue: more may not be better. Future trials would need to define safe joint dosing, ideal injection frequency, durability, side effects, patient selection, and long-term cartilage outcomes.

There are also questions about the hydrogel. Collagen II is biologically relevant to cartilage, which makes it attractive as a delivery material. Yet injectable biomaterials must be tested carefully. Researchers will need to show that the gel does not trigger harmful inflammation, interfere with joint movement, break down too quickly, or remain too long. Manufacturing standards will matter. So will reproducibility. A therapy intended for widespread use must be reliable from batch to batch, clinic to clinic, patient to patient.

That does not mean a cure is around the corner. It does mean the treatment landscape is changing. Osteoarthritis research is moving beyond simple pain relief towards disease modification. Scientists are investigating nerve channels, inflammatory pathways, growth factors, gene regulation, senescent cells, and advanced delivery systems. Some approaches will fail. Some may work only for certain subgroups. The best future treatments may combine rehabilitation, weight management, biomechanics, targeted medicine, and local biomaterials.

For now, lacosamide-loaded hydrogel remains an experimental strategy. Its promise lies in the neatness of the concept: repurpose a known medicine, target a channel involved in both pain and cartilage damage, then keep the drug inside the joint long enough to work.

If clinical trials confirm the preclinical findings, the impact could be substantial. Osteoarthritis affects millions worldwide and is a leading cause of disability, lost mobility, and reduced quality of life.

Even a treatment that slows progression, rather than fully reverses disease, could help people stay active for longer. Less pain. Better movement. Fewer systemic medicines. More time before surgery.

That is the newsworthy promise here. A carefully designed local treatment that may turn a familiar drug into something more targeted, more durable, and more useful for a disease that badly needs better options.