Knee gel injections are a popular and non-surgical option for managing osteoarthritis and persistent knee pain. Many patients ask, “How long do knee gel injections last?” Knowing how long you can expect relief is important for making informed treatment choices and setting realistic expectations. This article offers a clear, evidence-based guide on the typical duration of relief from different knee gel injections and the factors that can affect their effectiveness.

How Knee Gel Injections Work: A Brief Overview

Knee gel injections work by improving the natural lubrication in your joint or by encouraging healing. The most common type is hyaluronic acid (HA) injections, such as Synvisc and Euflexxa. Hyaluronic acid is a natural substance in joint fluid that cushions and lubricates the knee, helping to reduce pain and improve movement. Osteoarthritis often reduces the quality and amount of this fluid, so HA injections aim to restore it.

More recently, new treatments like polyacrylamide hydrogels, marketed as Arthrosamid, have become available. These hydrogels not only replace fluid but also “adhere to and bulk up the synovial membrane and act as a scaffold to treat the synovium” (Cole et al., 2022)

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

. Another option is platelet-rich plasma (PRP) injections, which use components of your own blood to promote tissue repair. Because these treatments work in different ways, the length of relief they offer varies.

Comparing Longevity: Evidence-Based Timelines for Leading Injections

Studies show that the duration of relief differs depending on the injection type. Traditional hyaluronic acid injections typically provide pain relief for about six months, although this can vary between three and nine months depending on the individual.

Polyacrylamide hydrogel injections like Arthrosamid tend to offer longer-lasting benefits. Research has found “statistically significant… efficacy of PAAG hydrogel at one year post injection,” with some studies showing positive effects lasting up to two years (Cole et al., 2022)

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

. In one randomised trial, the polyacrylamide hydrogel “was non-inferior to hyaluronic acid at 26 weeks and approached superiority at 52 weeks” (Bliddal et al., 2023)

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. https://doi.org/10.1302/1358-992x.2023.13.081

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As for PRP injections, results vary due to different preparation methods, but many patients experience relief lasting six to twelve months.

Key Factors Affecting Knee Gel Injection Longevity

Several factors influence how long the relief lasts. The stage of your osteoarthritis is vital; those with milder joint damage tend to enjoy longer-lasting benefits. Your age, body weight, and activity levels all play important roles as well. For example, people under 70 with a healthy body mass index (BMI) may see better results with polyacrylamide hydrogel (Bliddal et al., 2023)

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. https://doi.org/10.1302/1358-992x.2023.13.081

. Your unique biological response also matters — factors such as metabolism and inflammation affect how quickly the injected material works or wears off.

It’s important to talk through your personal situation with a healthcare professional to ensure the best treatment choice and to set realistic expectations.

Real-World Experiences: Expert and Patient Perspectives

Clinicians have noted that Arthrosamid is safe with “no long-lasting adverse events reported” (Cole et al., 2022)

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

. Patients often report significant improvements in pain and mobility, with some experiencing relief lasting nearly a year from Arthrosamid injections (Bliddal et al., 2023)

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. https://doi.org/10.1302/1358-992x.2023.13.081

. Additionally, one recent study found that patients receiving Arthrosamid had the highest rate of acceptable symptom states, with 72% feeling well at three months (Aykac et al., 2025)

Aykaç, B., Dinç, M., Nar, Ö. O., Karasu, R., & Bayrak, H. Ç. (2025). Comparative efficacy of polyacrylamide hydrogel versus hyaluronic acid and corticosteroids in knee osteoarthritis: A retrospective cohort study. Medicine, 104(38), e44655. https://doi.org/10.1097/md.0000000000044655

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When and Why Repeat Injections May Be Needed

Repeat injections are often given once symptoms start to return. For hyaluronic acid, this is usually every six to nine months. Arthrosamid tends to last longer; some patients only need a repeat injection after 12 months or more (Bliddal et al., 2023)

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. https://doi.org/10.1302/1358-992x.2023.13.081

. Importantly, evidence shows that Arthrosamid offers “comparable short-term efficacy and modest advantage at 6 months. However, long-term superiority is limited” (Aykac et al., 2025)

Aykaç, B., Dinç, M., Nar, Ö. O., Karasu, R., & Bayrak, H. Ç. (2025). Comparative efficacy of polyacrylamide hydrogel versus hyaluronic acid and corticosteroids in knee osteoarthritis: A retrospective cohort study. Medicine, 104(38), e44655. https://doi.org/10.1097/md.0000000000044655

. Your healthcare provider will help decide the best timing and approach for repeat injections based on your individual response and progress.

Conclusion

Knee gel injections provide an effective option for relieving osteoarthritis knee pain, with relief lasting anywhere from several months up to two years depending on the type and individual factors. Traditional hyaluronic acid injections usually last around six months, whereas newer treatments like Arthrosamid may offer benefits extending to one or two years for some patients. Your age, weight, arthritis severity, and biological response all influence how well and how long injections work. Understanding these details will help you have informed conversations with your clinician and tailor a treatment plan suited to your needs. Advances in knee injection therapies continue to expand options, empowering patients to manage pain and mobility with confidence.

This article uses British English spelling and style, combining expert knowledge with clear, patient-friendly language to guide those seeking information about knee gel injections.