Introduction

Medial-compartment osteoarthritis (OA) of the knee is a common and often challenging condition that primarily affects the inner part of the knee joint. This type of OA can cause ongoing pain, reduce how far you can walk, and make standing uncomfortable — all of which affect daily life and overall wellbeing. The term ‘medial-compartment’ refers to the inner side of the knee, where the cartilage, a smooth tissue that cushions the joint, tends to wear away due to forces called ‘varus load’—in simpler terms, a bending force placing extra pressure on the inside of the knee. As this cartilage thins, the knee’s function deteriorates, bringing about the typical symptoms of OA. Recently, there has been growing interest in new injectable treatments like Arthrosamid, designed to tackle these issues directly. This article looks at how Arthrosamid might help people struggling with inner-knee OA to ease discomfort and improve mobility.

Understanding Medial-compartment Knee OA

Medial-compartment knee OA is marked by the breakdown of cartilage mostly on the inside of the knee joint. This is often linked to a physical alignment change called “varus deformity,” where the knees bow outwards, putting more stress on the inner knee. This extra pressure often leads to sharp or aching pain when walking or standing for long periods. Such symptoms usually limit how far a person can walk comfortably and affect overall mobility.

The cartilage in this part of the knee generally wears down faster because of the uneven weight distribution and mechanical stress. Various factors increase the risk of developing medial-compartment OA, including ageing, being overweight, previous injuries, and repetitive strain on the knee. Knowing these helps guide effective ways to manage the condition.

Arthrosamid: How It Works and What Patients Can Expect

Arthrosamid is a newer kind of injection that cushions and supports the knee joint, particularly focusing on the medial (inner) compartment. Unlike traditional steroid or hyaluronic acid injections that mainly reduce inflammation or lubricate the joint temporarily, Arthrosamid uses a synthetic gel to gently fill the joint space and soften the impact between worn cartilage surfaces.

This cushioning helps to reduce friction, potentially easing pain during activities like walking and standing. The procedure is usually done on an outpatient basis and involves a carefully targeted injection into the inner knee. A recent study found that “PAAG provided improvement in knee OA symptoms over 24 months, in older, non-diabetic patients with lower KL grades” (Gao et al., 2025b), highlighting which groups might benefit the most. However, the same research points out that “absence of a control group and limited outcome measures should be considered” (Gao et al., 2025b), reminding us that while Arthrosamid can be helpful, it’s not a guaranteed cure and results may vary.

How Arthrosamid Compares with Other Treatments for Medial-compartment OA

Medial-compartment knee OA can be managed through various methods, each with its strengths and limitations. Physiotherapy focuses on strengthening muscles around the knee to improve support but requires commitment and may not fully relieve pain in later stages. Oral painkillers like NSAIDs can ease symptoms, but long-term use carries risks of side effects. Surgery – such as realignment osteotomy or knee replacement – is usually a last resort due to its invasiveness and recovery time.

Arthrosamid offers an alternative by addressing the cushioning lost as cartilage wears away, particularly under the added pressure of varus load. It may help some patients maintain better mobility and delay the need for surgery. The same long-term study showed “49 patients required total knee replacement over 2 years, with those having more severe OA more likely to undergo surgery” (Gao et al., 2025b). This highlights that Arthrosamid might suit those with milder to moderate OA best. It’s also worth noting that British orthopaedic experts support bone cement use in specific cases, such as fractures or cancer patients, whereas elective knee OA care—like at MSK Doctors—often involves uncemented implants, reflecting modern best practices.

Expert Care: Professor Paul Lee and the MSK Doctors Team

Professor Paul Lee is an internationally recognised expert in cartilage health and regeneration, advising the Royal College of Surgeons of Edinburgh. His deep experience makes him a trusted figure for patients seeking advanced knee OA treatments.

At MSK Doctors, patients benefit from a collaborative team with wide-ranging expertise and access to the latest treatments. The clinic takes a personalised approach, ensuring therapies like Arthrosamid are delivered with care tailored to each individual’s needs. For those requiring surgery, MSK Doctors favour uncemented knee implants, achieving excellent results supported by current research. This means guidance around bone cement relates minimally to their patients’ care. Overall, this expert environment helps patients make informed choices and experience better outcomes.

Conclusion

Arthrosamid offers a promising option for people managing medial-compartment knee osteoarthritis, especially those living with inner-knee pain and stiffness. By cushioning the joint and reducing friction, it adds a valuable tool to the range of non-surgical treatments.

If you’re considering Arthrosamid, it’s important to consult experienced professionals like those at MSK Doctors. They can provide personalised advice and create a tailored care plan to suit your needs. With ongoing advances in understanding and treating OA, treatments like Arthrosamid underline the vital role of expert guidance and innovation in improving quality of life.

References

• Gao, H. C. K., Akhtar, M., Creedon, C., Nar, Ö. O., Verma, T., & Lee, P. Y. F. (2025b). Polyacrylamide hydrogel injections in knee osteoarthritis: A PROMs-based 24 month cohort study. Journal of Clinical Orthopaedics and Trauma, 33, Article 103136. https://doi.org/10.1016/j.jcot.2025.103136
• Gao, H. C. K., Akhtar, M., Creedon, C., Nar, Ö. O., & Lee, P. Y. (2025a). The impact of patient factors on the minimal clinically important difference of Arthrosamid polyacrylamide hydrogel injection for knee osteoarthritis: A cohort study. Osteoarthritis and Cartilage, 33(Supplement 1), S388. https://doi.org/10.1016/j.joca.2025.02.648