Arthrosamid

Arthrosamid is a new type of conservative treatment options for knee osteoarthritis. It is an injectable polyacrylamide hydrogel that contains polyacrylamide (2.5%) and non-pyrogenic water (97.5%). The unique molecular structure allows normal water exchange and integration with the surrounding soft tissue.

Administered under ultrasound guidance to confirm intraarticular location, once injected into the joint cavity the polyacrylamide hydrogel integrates into the synovial membrane. This process takes around 2-3 months, the non-absorbable, non-biodegradable and non-migratory characteristics of arthrosamid provides durable augmentation of the inner joint capsule Polyacrylamide Hydrogel Injection for Knee Osteoarthritis: A 6 Months Prospective Study – White Rose Research Online offering cushioning and lubrication properties, enhancing the joint ability to absorb shock and reducing friction during movement. It has also been shown to have an anti-inflammatory effect, breaking the inflammatory cycle associated with OA and restoring joint homeostasis.

The injection can take up to 12 weeks to take full effect. Patients often seen a steady improvement in symptoms a lot sooner as the hydrogel integrates into the synovial membrane.

The procedure

You will initially need to have a consultation with one of our clinicians to assess your suitability. You will need to have had a recent X-ray of your knee to ensure that this particular injection is appropriate and to confirm the diagnosis. During the consultation the potential risks and benefits will be discussed with you, and you will be given the opportunity to ask any specific questions.

For the procedure, prophylactic antibiotics will be given 1 hour before. There are no specific patient requirements prior to the injection; we do recommend wearing loose-fitting clothes to allow easy access to the knee and, where possible, arranging for someone to drive you home following the procedure.

The procedure itself is straightforward and will take around 10-15 minutes to complete.

You will be positioned comfortably with clear access to the knee. The area will be prepped and cleaned.
Local anaesthetic will initially be injected to numb the area.
Using an ultrasound machine for guidance, a needle will be inserted into the joint. Once the correction position is confirmed, the Arthrosamid hydrogel will be administered.
The needle will be removed, and a small dressing will be applied to the injection site that must be kept clean and dry for 24 hours.

What are the potential risks?

An Arthrosamid injection is considered very safe, but as with any injection procedure, there are some potential risks and side effects.

Infrequent and mild side effects include:

Pain following the injection, which can last a few days, rarely sometimes longer.
• Localised bruising (more of a risk if patients are on blood thinners/anticoagulated)
A feeling of fullness in the knee with some associated stiffness that is temporary and will improve with time.

Rare risks / Complications include

Infection where the needle enters the joint. This is extremely rare and mitigated by proper sterile techniques. If the pain in your joint suddenly gets worse and your joint feels hot, swollen and warm to the touch, accompanied by you feeling unwell, you should seek urgent medical advice, typically from AE. They happen in about 1 in 3,000 to 50,000 people.
Allergic reaction to the local anaesthetic or equipment used during the procedure. Again, this is extremely rare. You will be asked to wait around for a short period of time after the procedure to monitor for any signs or symptoms.

Does it work?

Evidence shows beneficial effects in reducing pain and improving function in symptomatic knee OA varying from 1 to 3 years or longer in appropriate patients.

Less favourable results are reported in patients with established ‘bone on bone’ OA or with significant malposition (valgus/varus) alignment; in these patients, typically a joint replacement is their best option for sustained relief. It is not recommended in patients with inflammatory arthritis or patients with metabolic diseases such as gout, which may be adding to their knee symptoms.