Arthrosamid Injection

Arthrosamid is an injection that changes the synovial membrane of the joint. It uses polyacrylamide which implants itself within the lining allowing the knee to be less stiff and inflamed.

Compared to cartilage breakdown, synovial inflammation (synovitis) is generally considered to be the more direct and primary source of joint pain.

The articular cartilage is actually aneural, which means that there are no nerve endings here that transmit pain signals. Instead, pain is detected mainly through the synovium and the the surrounding joint capsule, soft tissue, and bone just beneath the cartilage.

In fact, it is well known that even in those with severe, “bone-on-bone” arthritis, there can be no pain if there is no associated inflammation or structural issue.

Polyacrylamide has been studied for more than 20 years and has been used in humans since 2010. It received Health Canada approval in early 2025.

The medical research for this procedure is continually evolving. It does not work for everybody. Please speak with your physician to determine if this is the right treatment for you.

What are the benefits?

This is a reasonable option as either first-line treatment, or in cases where other injections like cortisone, hyaluronic acid, or PRP have not worked. Polyacrylamide can provide benefit even in severe cases, as it’s focus is not on the cartilage itself, but instead the synovium which drives the inflammatory process. After a single injection, patients begin to experience pain relief within 4-12 weeks.

How long will my pain be reduced?

Polyacrylamide does not degrade and can provide relief up to 5 years.

How often can I have this done?

Repeat injections can be performed indefinitely.

Who can’t have this done?

Any patient who may appear to have:

• Infection within the body, near the site of administration, or the actual joint itself
• Recent knee arthroscopy within the last 6 months

Safety and effectiveness have not been established in patients under 18 years or in pregnant/lactating women

What should I do in advance of my injection?

You will be prescribed antibiotics prior to your procedure. Please ensure to take this 1-6 hours prior to the injection. This is to avoid severe infections, as the polyacrylamide is not meant to degrade like other injections.

What do I need to know about the injection later on?

If you are scheduled to have a surgical or dental procedure in the future, you should tell the treating doctor that you have a permanent hydrogel implant as this may require prophylactic antibiotic therapy.

What are the side effects?

Common, but not severe

1. Pain after injection: A post-injection flare occurs in up to 11% of patients (Puttick 1995; Pullman-Moor 2002). Similar to steroid injections, it usually settles within 2 days. Application of ice and simple pain medications (e.g. Tylenol, Advil) can help, if desired.
2. Pain during the procedure: The skin is the most sensitive part when it comes to any injection. We minimize this by using local anesthetic and/or a vapocoolant spray on the skin. Pain associated with the injection is usually brief and well-tolerated.

Not common, but potentially severe

1. Infection: When a needle is passed through the skin into the body, there is a very small chance of introducing a joint infection. The chance of this occurring is extremely low, less than 0.002%, or equivalent to being struck by a car as a pedestrian and experiencing a catastrophic event. To minimize this risk, we not only follow the WHO minimum best practice standards for injections, but use sterile gloves, sterile ultrasound probe covers, and sterile ultrasound gel.
2. Allergy: A swelling reaction to the local injectate can occur at the site of administration. We ask all patients to remain in the clinic waiting room afterwards for a minimum of 15 minutes to observe for any adverse reactions to the medication. An allergic reaction is more likely with repeated injections.
3. Bleeding: This is a greater risk if you have a known bleeding disorder or are taking blood thinners. By using ultrasound guidance, there is less “poking” around to get to the target tissue of interest, and thus less theoretical risk of bleeding. Pressure is maintained over the skin afterwards to reduce bleeding.

Systemic Side Effects

No specific reactions have been described.

Can I drive afterwards?

For most injections, people can drive afterwards. Nonetheless, bringing a driver is always a good idea just in case. We ask all patients to remain in the clinic waiting room for a minimum of 15 minutes afterwards to observe for any adverse reactions.

Can I play sports afterwards?

This depends on the type of sport and intensity, but we generally recommend taking it easy for 2 days as post-injection flares may occur. If steroid was provided, this takes effect after day 2. Overall, please be mindful with anything you do and listen to your body.

How much does this cost?​

Please see our fees and financing or contact us for more information.