For many people, persistent pain on the inner side of the knee is a daily struggle. This common discomfort often results from medial-compartment knee osteoarthritis (OA), a condition where the cartilage protecting the inner knee gradually wears away. The result is pain, stiffness, and difficulty with activities like walking or using stairs. Arthrosamid , a new injectable gel, is offering fresh hope by targeting this inner- knee pain and helping people move more comfortably.

Understanding Medial-Compartment Knee Osteoarthritis

The knee joint is made up of several compartments, with the medial compartment found on the inside where the thigh bone (femur) meets the shin bone (tibia). Because this section bears much of the body’s weight during everyday movements , it’s more prone to wear and tear over time.

In medial-compartment knee OA, cartilage breaks down in this inner section, causing the bones to rub together. This friction brings on pain, swelling, and stiffness—especially after periods of rest. Everyday movements like walking, rising from a chair, or climbing stairs can become increasingly difficult.

One contributing factor is something called the knee adduction moment—a biomechanical shift that places extra pressure on the inner knee. Over time, this added load makes the cartilage in the medial compartment more vulnerable, worsening pain and limiting mobility.

People with medial knee OA may also experience joint instability. This is sometimes associated with issues such as anterior cruciate ligament (ACL) deficiency, and can present as both pain and a feeling that the knee might "give way." To compensate, the body may rely on increased contraction of muscles on the inner side of the knee, but this can actually raise joint compression and risk of further damage if not managed well.

How Arthrosamid Works

Arthrosamid is a soft, water-based gel made from polyacrylamide hydrogel (PAAG). During treatment, about 6 millilitres of the gel are gently injected into the inner part of the knee joint , with ultrasound used to ensure precision.

Once injected, the gel integrates into the joint lining (the synovial membrane ), enhancing its thickness and cushioning the joint. This helps improve lubrication, reduces friction , and absorbs shock during movement. Additionally, Arthrosamid acts as a framework that can help the joint lining heal and calm inflammation.

What makes Arthrosamid stand out is its lasting effect. Clinical research shows that a single injection can offer pain relief for a year or more, often longer than traditional options like hyaluronic acid or steroid injections.

Clinical Evidence: Effectiveness and Safety

Clinical studies give encouraging support for Arthrosamid ’s effectiveness in relieving pain and improving knee function for people with medial-compartment knee OA.

In one study, patients experienced a dramatic reduction in their pain, with average pain scores falling from about 7 out of 10 before treatment to around 3 just three months after their injection. These improvements not only lasted but also remained steady at six and twelve months. In comparison, the effects of more common injections often fade sooner.

Other research supports these findings. For example, studies have found that older patients, those with lower grades of knee osteoarthritis , and people without diabetes often see the greatest benefits from Arthrosamid . Importantly, while some people with more advanced OA may eventually require knee replacement surgery , Arthrosamid may help delay that need and improve quality of life in the meantime.

Beyond pain relief , patients receiving Arthrosamid consistently report better joint function, measured by tools like the WOMAC index (which tracks pain, stiffness, and daily activities). Arthrosamid also has a strong safety record, with very few side effects and no major complications reported over the long term. However, it’s worth noting that more research—especially with control groups—will help clarify these promising results.

The Arthrosamid Experience at London Cartilage Clinic

At London Cartilage Clinic, getting an Arthrosamid injection is a straightforward, patient-centered process.

Your journey starts with a thorough consultation to review your medical history and discuss whether Arthrosamid is a good fit for you. On the day of treatment, your knee is carefully cleaned, and a local anesthetic is applied to keep you comfortable.

Using ultrasound for accuracy, the doctor injects the gel directly into the inner knee . After a short observation period to ensure you feel well, most people are able to go home the same day.

You’ll be in the care of Professor Paul Lee , a leading expert in orthopaedics and rehabilitation. His expertise, together with the clinic’s calm, welcoming environment, ensures you feel supported from start to finish.

Rehabilitation and What to Expect

Following your Arthrosamid injection , you’ll need to take it easy for a few weeks. Avoid high-impact activities like running and heavy lifting, but gentle walking and movement are encouraged.

A personalised rehab programme, often including physiotherapy, will help to maintain flexibility and strengthen muscles around your knee. These exercises are tailored to help you get the most benefit from your treatment.

Many patients start to notice pain relief within weeks—often with the greatest improvements arriving between three and six months after injection. While Arthrosamid isn’t a cure for osteoarthritis , it can be an important tool for managing symptoms, boosting mobility, and supporting an active lifestyle.

With the right recovery plan, you can look forward to moving more freely and returning to everyday activities that matter most.

Arthrosamid brings a new approach to managing medial-compartment knee osteoarthritis , providing added cushioning and support to the inner knee while easing pain and improving function. At London Cartilage Clinic, Professor Paul Lee and his team offer expert, compassionate care to help guide you through treatment and recovery.

For medical advice tailored to your needs, always consult a qualified healthcare professional.

References

Gao, H. C. K., Akhtar, M., Creedon, C., Nar, Ö. O., Verma, T., & Lee, P. Y. F. (2025). Polyacrylamide hydrogel injections in knee osteoarthritis: A PROMs-based 24 month cohort study. Journal of Clinical Orthopaedics and Trauma. https://doi.org/10.1016/j.jcot.2025.103136

Lewek, M. D., Ramsey, D. K., Snyder‐Mackler, L., & Rudolph, K. S. (2005). Knee stabilization in patients with medial compartment knee osteoarthritis. Arthritis & Rheumatism, 52(9), 2845–2853. https://doi.org/10.1002/art.21237

Mancuso, F., Dodd, C. A. F., Murray, D. W., & Pandit, H. (2016). Medial unicompartmental knee arthroplasty in the ACL-deficient knee. Journal of Orthopaedics and Traumatology, 17(3), 267-275. https://doi.org/10.1007/s10195-016-0402-2