Introduction

If you’re living with knee osteoarthritis, you’ve probably wondered not only about the upfront cost of knee gel injections but also how long they actually last and what the overall expense might be over time. It makes sense — choosing a treatment isn’t just about the price tag but also about how effective it is and how often you’ll need repeat injections. This article will guide you through the differences between common injectable treatments, focusing on how long their benefits last, how often you might need them, and what that means for your wallet. By the end, you should feel better equipped to make an informed decision that suits both your health and budget.

Types of Knee Gel Injections and How Long They Last

There are two main types of knee gel injections used to treat osteoarthritis: the traditional hyaluronic acid (HA) injections, and the newer polyacrylamide hydrogels (PAAG), such as Arthrosamid.

Hyaluronic acid works by supplementing the natural fluid in your knee joint, improving lubrication and cushioning to reduce pain and stiffness. Typically, relief from HA injections lasts between six and twelve months. Polyacrylamide hydrogel, by contrast, forms a gel-like scaffold inside the joint, supporting the lining and providing longer-lasting comfort—often up to two years.

A recent systematic review highlights this clearly, stating that PAAG injections show “efficacy at one year post-injection and statistically significant results at two years.” This means some patients can enjoy longer-lasting relief with fewer injections over time.

What’s more, a clinical study comparing the two treatments found that PAAG “approached superiority to HA at 52 weeks,” and was statistically better for certain groups, including younger patients (under 70), those with a normal body mass index (BMI), or those with moderate osteoarthritis. So, the benefits of PAAG might be even more noticeable depending on individual factors.

It’s also worth noting that over the past thirty years, advances in polymer chemistry and hydrogel technology have brought many new injectable products to clinical use, improving safety and effectiveness. This ongoing progress means patients now have a wider range of options than ever before.

How Often Might You Need Repeat Injections?

The typical length of pain relief directly affects how often injections need to be repeated. Because hyaluronic acid’s effects generally last six to twelve months, many patients find they need two or more injections each year. Polyacrylamide hydrogel injections last much longer, so usually only one treatment every 18 to 24 months is necessary.

Interestingly, studies show that for most patient groups, PAAG injections perform as well or better than HA shots. For example, in certain subgroups—those with normal BMI or younger than 70—the benefits were notably greater with PAAG. However, for patients with more advanced osteoarthritis (a higher Kellgren-Lawrence grade 4), HA sometimes showed a slight edge, though this wasn’t statistically significant.

Understanding how often injections are needed is crucial, as it directly influences the total cost and convenience of treatment, helping you weigh your options more effectively.

Breaking Down the Costs Over Time

It’s one thing to know the price per injection, but the bigger question is, what's the total cost over time?

Let’s say a single HA injection costs about £300. If you need two each year, that adds up to £600 annually. By comparison, a PAAG injection might cost around £800 but only needs repeating every two years, so the yearly cost averages to roughly £400.

This simple calculation shows why considering “cost effectiveness” means looking beyond the initial price. Sometimes, paying more upfront for a longer-lasting treatment can save money — and trips to the clinic — down the line.

What Affects How Long Injections Last?

How long an injection provides relief can vary quite a bit from person to person. Factors such as your overall health, activity level, weight, the severity of your osteoarthritis, and even the brand of injection can all influence how well and how long the treatment works.

The studies we’ve mentioned support this. For example, patients with a normal BMI, younger age, or moderate osteoarthritis tended to get the best results from PAAG injections. This personalised variability means that talk­ing to your doctor about your specific situation is key to setting realistic expectations and planning your treatment.

Deciding What’s Best for You in the Long Run

Choosing between more frequent, lower-cost injections and fewer, higher-cost but longer-lasting ones isn’t always straightforward. While it’s tempting to focus on the immediate cost, it pays to look at the bigger picture: total costs, frequency of treatment, convenience, and your personal health profile.

By understanding both the duration of knee gel shots and the overall financial implications, you can better discuss options with your healthcare provider and choose a treatment plan that fits your lifestyle and budget.

Final Thoughts and Seeking Personal Advice

Remember, every patient’s journey is unique. What works best for one person may not be ideal for another. Always consult your healthcare professional to tailor treatment plans to your needs.

On safety, long-term evidence is reassuring: PAAG injections “have been shown to be safe with no long-lasting adverse events reported.” Knowing a treatment is both effective and safe provides confidence when making choices about managing your knee osteoarthritis.

References

Cole, A., Maulana, R. K., Whitehead, J. P., & Lee, P. Y. F. (2022). A systematic review of the novel compound Arthrosamid polyacrylamide (PAAG) hydrogel for treatment of knee osteoarthritis. Medical Research Archives, 10(8). https://doi.org/10.18103/mra.v10i8.2950

Clegg, J. R., Adebowale, K., Zhao, Z., & Mitragotri, S. (2024). Hydrogels in the clinic: An update. Bioengineering & Translational Medicine, 9(6). https://doi.org/10.1002/btm2.10680

Bliddal, H., Beier, J., Hartkopp, A., Conaghan, P. G., & Henriksen, M. (2023). Polyacrylamide hydrogel versus hyaluronic acid in knee osteoarthritis: A subgroup analysis of a randomized study. Orthopaedic Proceedings, 105-B(SUPP_13), 81-81. https://doi.org/10.1302/1358-992x.2023.13.081