Introduction

Knee osteoarthritis (OA) is a common and often debilitating condition that affects millions of people in the UK. As the disease progresses, many patients eventually require total knee replacement (TKR) surgery. While TKR can provide significant relief, it’s typically considered only after other treatments have failed, as surgery carries its own risks and can mean a lengthy recovery. The demand for TKR also places a substantial financial burden on the National Health Service (NHS).

This reality has created a growing interest in innovative, less invasive therapies that can manage OA symptoms and postpone, or possibly avoid, the need for surgery. One such therapy gaining attention is polyacrylamide hydrogel (PAAG) injections. Recent studies suggest PAAG could effectively delay TKR for certain patients with knee OA, improving quality of life while reducing strain on the NHS.

What Is Polyacrylamide Hydrogel and How Does It Work?

Polyacrylamide hydrogel is a water-based gel made from polyacrylamide, a substance well-suited to biomedical applications. When injected into an arthritic knee joint , the gel acts as a cushion — helping to restore some of the shock-absorbing and elastic qualities that healthy cartilage provides. This process, known as visco-supplementation, sets PAAG apart from steroid injections or hyaluronic acid treatments, which mainly reduce inflammation or lubricate the joint. The unique structure of PAAG offers more support and can deliver longer-lasting relief, making it a promising choice for those seeking alternatives to surgery. Clinical research has shown that PAAG injections are both safe and effective for knee OA.

Who Benefits Most from PAAG Injections?

PAAG injections are not a one-size-fits-all solution, and careful patient selection is key to achieving the best possible outcomes. Research has identified several factors that make patients more likely to respond well:

• Age: Older patients often experience greater benefits, possibly due to less demanding joint usage.
• Severity of OA: Those with milder osteoarthritis (lower Kellgren-Lawrence grades) tend to respond better compared to those with advanced joint damage.
• Diabetes Status: Patients without diabetes see improved results, likely because diabetes can interfere with healing and joint health.
• Number of Affected Knees: People with OA in both knees (bilateral OA) may fare better than those with only one affected knee.

By considering these factors, healthcare providers can more accurately identify which patients are likely to benefit most from PAAG injections, helping to delay surgery and improve quality of life.

Benefits Beyond Symptom Relief: Economic and Healthcare Impacts

Delaying or reducing the need for knee replacements benefits not just individual patients, but the healthcare system as a whole. TKR is a costly procedure requiring significant hospital resources. If PAAG injections can safely delay the need for surgery, the NHS could save substantial amounts of money. Fewer surgeries mean less pressure on hospital waiting lists, more efficient use of operating rooms, and reduced aftercare needs.

For patients, the benefits are equally significant. Avoiding or postponing surgery means less risk, less time spent recovering, and a chance to maintain daily activities for longer. Since patients with more advanced OA are more likely to require surgery despite injections, early and targeted use of PAAG could have a meaningful impact on both personal and system-wide health outcomes.

Looking Ahead: Challenges and Future Research

Although PAAG injections show promise, more work is needed before they become a standard treatment option. Many current studies lack control groups, making it difficult to directly compare PAAG’s effectiveness with other approaches. Inconsistent outcome measurements across studies also make it challenging to draw firm conclusions. Additionally, little is known about the long-term impact of these injections — will they continue to benefit patients for years, or does their effect eventually diminish?

Future research should focus on well-designed clinical trials that include control groups and follow patients for longer periods. Such studies will provide clearer answers about how best to use PAAG and which patients are likely to enjoy the most lasting benefits.

Conclusion

Polyacrylamide hydrogel injections are emerging as a promising treatment to delay — and possibly avoid — total knee replacement for carefully selected patients with knee osteoarthritis. By considering key factors such as age, OA severity, diabetes status, and whether one or both knees are affected, clinicians can individualise care and maximise the benefits of PAAG therapy. This approach not only improves outcomes and quality of life for patients, but also offers valuable cost savings and helps reduce pressure on the NHS. While further research is needed to clarify long-term benefits, current evidence suggests PAAG could play an important role in modern knee OA management.