Arthrosamid Injection: Hydrogel for Knee Osteoarthritis & Pain Relief

Discover how Arthrosamid injections offer a promising solution for knee osteoarthritis and effective pain relief. This guide explores the benefits, procedure, and what to expect from this innovative treatment.

What is Arthrosamid® Injection?

Arthrosamid Mechanism of Action

Arthrosamid® is a hydrogel consisting of 2.5% cross-linked polyacrylamide and 97.5% water. Once injected, the advanced hydrogel integrates with the synovial membrane. It works by reducing inflammation, and also cushions and lubricates, providing long-lasting support and reducing friction within the knee joint, thus reducing pain.

Overview and History of Arthrosamid®

Arthrosamid® has been studied for over 20 years. It is a hydrogel injection designed to alleviate knee pain associated with osteoarthritis.  Treatment started with small animals like cats and rabbits and then expanded to race horses in 2009, as vets saw dramatic symptom improvement in horses with advanced osteoarthritis. In 2021, after 10 years of rigorous safety testing, Arthrosamid was approved in Europe for the treatment of knee osteoarthritis. Arthrosamid has been approved by Health Canada since April 2024.

To date, over 26,000 patients have been safely treated across over 400 clinics in Europe, New Zealand and most recently, Canada. This non-surgical treatment involves an ultrasound guided injection into the knee joint.  The goal is to provide long-lasting pain relief and improve knee function, offering an alternative to other injectables and delaying or avoiding knee replacement surgery.

What is Knee Osteoarthritis?

Knee osteoarthritis is a degenerative joint disease affecting the knee joint, leading to the chronic inflammation and breakdown of cartilage. This results in pain, stiffness, and reduced knee function. Osteoarthritis can significantly impact daily activities, making even simple movements challenging and uncomfortable.

Causes and Risk Factors

Several factors contribute to knee osteoarthritis, including age, genetics, and obesity. Previous knee injuries and repetitive stress from strenuous activities can also increase the risk. Understanding these risk factors can help in early intervention and management to alleviate pain.

Symptoms and Diagnosis

Here are some common signs that you might have knee osteoarthritis. These can include:

• Knee pain
• Stiffness and swelling
• Decreased range of motion
• A grating sensation in the knee joint

Diagnosis usually involves a detailed medical history, physical examination, X-rays, and sometimes MRI scans to assess the extent of cartilage damage and guide appropriate treatment strategies.

How Arthrosamid® Differs from Other Treatments

Unlike hyaluronic acid injections or corticosteroid injections, Arthrosamid® is a non-biodegradable hydrogel, designed to provide long-lasting pain relief for knee osteoarthritis.  While hyaluronic acid degrades over time, requiring repeat injections, Arthrosamid® aims for sustained improvement after a single treatment.

Benefits of Arthrosamid® Injection

Long-lasting Pain Relief for Knee Osteoarthritis

Arthrosamid hydrogel injection seems to offer significant and long-lasting pain relief for knee osteoarthritis. Studes show improvment in pain which can last for several years. Unlike treatments that require frequent repetition, a single injection of this hydrogel can provide sustained improvement. This is particularly beneficial for those seeking a non-surgical option to manage their knee pain and improve knee function.

Evidence of Efficacy

Clinical studies have demonstrated the efficacy of Arthrosamid® in reducing knee pain associated with osteoarthritis. The hydrogel cushions the knee joint and integrates with the synovial membrane, providing proven pain relief for knee osteoarthritis. Many patients experience a noticeable improvement in their symptoms after receiving the arthrosamid treatment.

How well does Arthrosamid work?

The overall response rate for Arthrosamid after one year is 73%.  Younger patients seem to respond better than older.  

• For patients aged < 50:  100% respond well
• For patients aged < 60:   94% respond well
• For patients aged < 70:   80% respond well

Administration of Arthrosamid® Injection

Arthrosamid Consultation Process

Before receiving an Arthrosamid injection, interested patients should receive a consultation to determine whether Arthrosamid is appropriate for their specific situation.   This should include a detailed medical history, physical examination and discussion of the risks and benefits of Arthrosamid as well as other treatments including medication, physical therapy, and other injections such as hyaluronic acid, cortisone, and PRP.  Imaging studies may also be ordered such as X-rays and MRI.

Procedure Overview

The Arthrosamid® injection is a relatively straightforward, non-surgical procedure. Prophylactic antibiotics will be prescribed as a single dose taken 1-6 hours prior to the treatment to minimize the risk of infection.   The injection is performed in clinic using ultrasound guidance.  The knee is carefully cleansed with an antiseptic solution and a small amount of local anaesthetic is usually administered to minimize discomfort prior to the injection into the knee joint.

Aftercare and Recovery

Following an Arthrosamid® injection, patients are advised to avoid strenuous activities for a short period. Mild swelling at the injection site is normal and can be managed with rest and painkillers. Most individuals can resume their normal activities relatively quickly, experiencing gradual improvement in knee function and reduced pain.

Potential Complications of Arthrosamid®

Common Side Effects

The most commonly reported adverse events are injection site reactions, including post-injection pain, swelling, and soreness that typically resolve within 24-48 hours. [1-2] In the largest randomized controlled trial, 28.9% of iPAAG-treated patients reported adverse device effects compared to 7.6% in the hyaluronic acid group, though all were classified as mild to moderate with no serious adverse events. [2]

These effects are generally mild and resolve within a few days with appropriate care and over-the-counter painkillers.

 Long Term Safety of Arthrosamid Hydro-Gel

A long-term, 10-year follow up study looked at 89 knees in 61 patients who were treated with Arthrosamid between 2010 and 2017 [6]:

• Observation time 10 years (range 7-14 years)
• Mean age: 64 years;
• Gender: 24 women and 37 men.
• 61 patients, 81 knees
• No significant adverse events associated with Arthrosamid were reported
• No allergic reactions, infections, or systemic complications from the iPAAG (Arthrosamid) injection

Of the 89 knees, 56% did not require knee replacement in the follow-up period. 44% knee replacements were performed after a mean time lapse of 3.4 years. No unusual findings or complications were noted during the knee replacements due to Arthrosamid.

Another long-term safety data study extending to 3 years show sustained tolerability. Between year 1 and year 3 of follow-up, 50 adverse events were reported by 29.8% of participants, but notably, none were assessed as related to the iPAAG injection. [1] No cases of septic arthritis, granulomatous reactions, or gel migration—complications that have been documented with polyacrylamide gel used in soft tissue augmentation—have been reported in the intra-articular knee osteoarthritis literature.

The mechanism underlying iPAAG’s safety appears related to its stable integration into synovial tissue. Histopathological studies demonstrate that the gel forms a sub-synovial layer traversed by thin strands of vascularized connective tissue and covered by synovial lining, with this structure persisting up to 2 years without evidence of inflammation or degradation. [3]

No systemic or immune-mediated complications (such as ASIA syndrome or autoimmune reactions documented with cosmetic polyacrylamide use) have been reported in the knee osteoarthritis treatment context.

Serious Complications to Watch For

No serious complications such as infection or severe allergic reactions have been documented in the clinical trials of intra-articular polyacrylamide hydrogel for knee osteoarthritis. [1-2]

In the largest randomized controlled trial comparing iPAAG to hyaluronic acid, all 41 adverse device effects reported in the iPAAG group (28.9% of participants) were classified as mild to moderate, with no serious adverse events reported. [2] The 3-year extension study similarly found that none of the 50 adverse events reported between year 1 and year 3 were assessed as related to the iPAAG injection. [1]

No cases of septic arthritis have been reported in the knee osteoarthritis literature for iPAAG. [4] This stands in contrast to the known risk of infection with intra-articular injections generally, where septic arthritis is recognized as a rare but serious complication of any intra-articular therapy. [4]

While the above is reassuring, it does not mean that serious complications such as infection is impossible.  Therefore, patients are advised to watch for and immediately report any concerning symptoms such as fever, chills, persistent or worsening pain, swelling, redness, etc.

Arthrosamid vs Other Treatments

There is no perfect treatment for osteoarthritis which works for everyone, and it’s important to remember that osteoarthritis naturally worsens over time as we age.  The following is a brief overview comparison Arthrosamid to other injectable treatments for osteoarthritis.

Hyaluronic Acid Injections

Hyaluronic acid gel injections are a common treatment for knee osteoarthritis and are effective for many patients at improving symptoms.  Specific name brands available in Canada include Durolane, Synvisc, and Monovisc.  Hyaluronic acid helps osteoarthritis through cushioning and lubrication.  However, it also degrades over time, needing repeat injections.  Symptom relief with hyaluronic acid usually lasts around 6 months.  On the other hand, Arthrosamid treatment is considered permanent, with symptom relief often lasting many years due to its long-lasting benefits of a non-biodegradable hydrogel.

PRP Injections

PRP (Platelet-Rich Plasma) injections involve injecting a concentration of the patient’s own platelets into the knee joint to promote healing and reduce pain. While some patients find PRP helpful for knee osteoarthritis, the results can vary. Arthrosamid® injection offers a different mechanism by cushioning the knee joint and integrating with the synovial membrane.

Cortisone Injections

Cortisone injections can provide quick pain relief for knee osteoarthritis by reducing inflammation. However, their effects are temporary, and frequent use can lead to cartilage damage and worsening arthritis.  Unlike Arthrosamid injections, which aim for long-lasting pain relief for knee osteoarthritis, cortisone injections are typically used for short-term symptom management.

Traditional Pain Relief Medications

Traditional pain relief medications, such as NSAIDs, can help manage knee pain from osteoarthritis. However, these medications often come with side effects and don’t address the underlying joint issue. Arthrosamid is a hydrogel injection aims to improve knee function and provide long-lasting pain relief at the injection site without systemic side effects.

Knee Replacement Surgery

Knee replacement surgery is an invasive option for severe knee osteoarthritis when other treatments have failed.  Surgery involves significant risk, recovery time and potential complications.  Arthrosamid is a hydrogel injection offers a less invasive alternative, providing pain relief for knee and improving knee function, potentially delaying or avoiding knee replacement.

Practical Tips for Managing Knee Osteoarthritis

Exercise and Physical Therapy

Regular exercise and physical therapy are essential for managing knee osteoarthritis. Strengthening the muscles around the knee joint provides better support and reduces stress on the joint. Physical therapy can also improve range of motion and flexibility, helping to alleviate stiffness associated with arthritis in the knee.

Diet and Weight Management

Maintaining a healthy weight is crucial for managing knee osteoarthritis. Excess weight places additional stress on the knee joint, accelerating cartilage breakdown. A balanced diet rich in anti-inflammatory foods can also help reduce pain and inflammation associated with arthritis and pain relief for knee.

Using Assistive Devices

Here’s how assistive devices can help individuals with knee osteoarthritis:

• Braces can help align the knee joint, offload or reduce pressure pain during movement.
• Canes can alleviate pressure on the knee joint, making walking easier and more comfortable, and improve knee function.

FAQs about Arthrosamid® Injection

Who is a Suitable Candidate?

Ideal candidates for Arthrosamid® injections are individuals with mild to moderate knee osteoarthritis who have not found adequate pain relief with conservative treatments. Patients should undergo a thorough orthopaedic evaluation to determine if Arthrosamid® is appropriate for their specific condition and provide long-lasting pain relief.

How Often Should Injections Be Administered?

Arthrosamid treatment is designed as a single injection therapy. Unlike hyaluronic acid injections or corticosteroid injections that require repeated administration, Arthrosamid® aims to provide long-lasting pain relief for knee osteoarthritis after just one injection, making it a convenient and effective treatment.

Cost and Insurance Coverage

The cost of an Arthrosamid treatment in Canada is currently between $4000 to $5000 and is not covered by BC Pharmacare.

For more information

We welcome patients to schedule a no-charge consultation regarding arthritis treatment options at our booking page, or directly using the following link:

Medical Consultation (no charge*): PRP Joint, Arthritis, Sports Injury Consultation

If you’re coming from out-of-town, we offer complimentary virtual consultations:
Virtual Consultation (out-of-town patients only)

References

1. Three-Year Follow-Up From a Randomised Controlled Trial of a Single Intra-Articular Polyacrylamide Hydrogel Injection in Subjects With Knee Osteoarthritis. Clinical and Experimental Rheumatology. 2025. Bliddal H, Beier J, Hartkopp A, Conaghan PG, Henriksen M.New
   
2. Polyacrylamide Gel Versus Hyaluronic Acid for the Treatment of Knee Osteoarthritis: A Randomised Controlled Study. Clinical and Experimental Rheumatology. 2024. Bliddal H, Beier J, Hartkopp A, Conaghan PG, Henriksen M.
   
3. Synovial Incorporation of Polyacrylamide Hydrogel After Injection Into Normal and Osteoarthritic Animal Joints. Osteoarthritis and Cartilage. 2016. Christensen L, Camitz L, Illigen KE, et al.
   
4. The Safety of Intra-Articular Injections for the Treatment of Knee Osteoarthritis: A Critical Narrative Review. Expert Opinion on Drug Safety. 2017. Nguyen C, Rannou F.
   
5. A Systematic Review of the Novel Compound Arthrosamid Polyacrylamide (PAAG) Hydrogel for Treatment of Knee Osteoarthritis. Medical Research Archives [Online], 10.8 (2022): n. pag. Web. 18 Feb. 2026. Cole, A., R. Maulana, J.P. Whitehead, & P.Y.F Lee.
   
6.  10-Year Follow-Up After Intra-Articular Injections of 2.5% Polyacrylamide Hydrogel for Knee Osteoarthritis. Bliddal, H.., et al. (2025) Presented at WCO-IOF-ESCEO 2025.