Injection Therapy

Arthrosamid® Injection

A non-biodegradable hydrogel injection designed to integrate with the joint lining and provide cushioning for knee osteoarthritis.

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What is a Arthrosamid® Injection?

Arthrosamid® is a non-biodegradable polyacrylamide hydrogel injection designed for patients with knee osteoarthritis. Unlike other injections that are gradually absorbed by the body, this hydrogel is designed to permanently integrate with the synovial membrane (the joint lining) to provide structural cushioning and reduce friction.

Procedure & Aftercare Details

Arthrosamid® Injection Explanation

1. Joint Anatomy Target

AnatomyClinical Approved

Arthrosamid® Injection Target

Permanent polyacrylamide hydrogel coating the inner synovium of the joint capsule.

2. Injection Needle Path

Needle PathClinical Approved

Arthrosamid® Needle Access Path

Strict aseptic injection path of permanent hydrogel under ultrasound guidance.

This outpatient procedure is conducted under strict sterile conditions:

1Comprehensive clinical assessment and review of diagnostic imaging to confirm suitability.

2Informed consent discussion detailing the nature of the hydrogel, risks, and alternatives.

3Rigorous sterile preparation of the knee joint area to minimize infection risk.

4Intra-articular injection of the hydrogel by the specialist under aseptic conditions.

5Application of a sterile dressing to the injection site.

6Review of post-injection monitoring and activity guidelines before discharge.

Clinical AccuracyUltrasound-Guided Injections

We highly recommend executing injections under real-time ultrasound guidance to ensure precise placement within the joint space, maximizing therapeutic safety and efficacy.

Learn About Guidance →

Clinical Characteristics Summary

Onset of Action4-8 weeks

Typical Duration12-24 months+

Primary MechanismSynovial cushion hydrogel integration

Main IndicationModerate-to-severe knee osteoarthritis

This information is for general patient education and does not replace an individual clinical assessment.

Clinical Presentation: 5-Year Patient Updates

Watch this clinical patient presentation highlighting the latest 5-year updates and long-term joint outcomes for Arthrosamid® hydrogel treatment.

How does it work?

Once injected, the hydrogel integrates with the synovial membrane of the knee joint. This integration aims to cushion the joint, restore lubrication, and reduce joint stiffness. Because it is non-biodegradable, the structural effect is intended to persist. Long-term clinical evidence continues to develop, and patient suitability is evaluated through a specialist consultation.

Who is this suitable for?

Patients Who May Be Considered

Patients with confirmed knee osteoarthritis who have not obtained sufficient pain relief from other non-surgical options.
Individuals seeking options with potential for longer-lasting structural joint cushioning.
Patients who are not suitable candidates for, or wish to delay, major knee replacement surgery.
Selected cases where temporary viscosupplementation has provided short-lived relief.

Who May Not Be Suitable

Active joint infection, skin infection, or inflammation at the injection site.
Patients who have undergone a knee arthroplasty (joint replacement) or have metalwork in the knee.
Recent knee surgery or arthroscopy within the past few months.
Severe knee joint deformity or gross instability requiring surgical correction.

Potential Benefits & Risks

Potential Benefits

Designed to integrate with the joint lining for long-term cushioning.
Aims to reduce friction and improve mobility in select patients.
Non-biodegradable formula means it is not absorbed by the body.
May assist in managing osteoarthritis pain when other conservative measures fail.

Risks & Limitations

Long-term clinical evidence continues to develop, and individual patient responses vary.
Potential for temporary post-injection side effects, including mild-to-moderate pain, stiffness, or joint swelling.
Small risk of joint infection, which is a serious complication for any intra-articular injection.
Not suitable for severe structural instability or advanced deformities that require surgical correction.
Higher initial cost compared to temporary viscosupplementation or steroid injections.

What happens during the procedure?

Knee injections are outpatient procedures completed in our sterile clinical rooms. The step-by-step process is detailed in the interactive guide above, including:

1. Preparation & CleaningJoint positioning, skin disinfection, and local anaesthetic.

2. Needle InsertionPrecise injection, often under ultrasound guidance.

3. Dressing & MonitoringSterile dressing applied and post-procedure check.

Needle placement may be performed under real-time imaging guidance depending on clinical indication.Learn about ultrasound-guided knee injections →

After the injection

Aftercare is focused on protecting the joint and monitoring for rare complications. Guidelines are outlined in the interactive tabs above. Remember to rest the joint for the first 48 hours and avoid unaccustomed heavy loads.

Frequently Asked Questions

No. Arthrosamid® is not a cure for osteoarthritis. While it is a non-biodegradable hydrogel designed to integrate with the joint lining and provide cushioning, it does not regenerate worn cartilage or restore the joint to a pre-arthritic state.

The appointment typically takes 20 to 30 minutes, allowing for a pre-procedure check, sterile skin preparation, administration of the hydrogel, dressing application, and review of aftercare advice.

It is strongly advised to arrange for someone else to drive you home. You may experience temporary stiffness, discomfort, or local swelling in the joint immediately after the procedure.

You should rest the knee and avoid strenuous exercise, running, gym training, or high-impact activities for at least 48 hours. Light daily walking is permitted if comfortable, with a gradual return to active physical therapy.

Arthrosamid® is administered as a single intra-articular injection. Because the hydrogel is non-biodegradable, a single treatment is intended to provide sustained cushioning, and routine repeat injections are not indicated.

Patients typically experience a standard needle prick and a feeling of fullness or pressure within the joint as the hydrogel is introduced. A local anaesthetic is used to minimize skin discomfort.

Yes. Detailed diagnostic imaging (an X-ray and/or MRI) is mandatory to evaluate the joint space, verify the severity of osteoarthritis, and ensure there are no contraindications present in the joint.

In selected patients with moderate osteoarthritis, the cushioning effect of the hydrogel may help manage pain and support function, potentially allowing them to delay surgery. This is determined via specialist consultation.

Which injection may be appropriate?

Choosing an injection therapy requires an individualized clinical assessment. The choice depends upon several factors, including:

Verified clinical diagnosis
Type and severity of symptoms
Diagnostic imaging findings (X-ray, MRI, Ultrasound)
Patient activity levels and functional goals
Previous conservative treatments attempted
Individual medical history, medications, and allergies
Potential clinical risks versus patient-specific benefits
Available non-injection treatment alternatives

⚠️ Only an individual consultation with our consultant orthopaedic surgeon can determine whether a knee injection is clinically appropriate for your condition.

Schedule a Clinical Consultation

To evaluate your knee symptoms and discuss whether an injection therapy is indicated, arrange a specialist consultation.

Call Clinic Book Assessment

Clinically Reviewed

Mr Ricardo J Pacheco (GMC 4145976)Consultant Trauma & Orthopaedic Surgeon

Last reviewed: 29 July 2026

Evidence & References

Clinical registry and trial data on polyacrylamide hydrogel (Arthrosamid) in knee osteoarthritis.
European consensus statements and safety monitoring publications.
Long-term follow-up clinical literature on viscosupplementation vs. permanent hydrogel integration.
Effectiveness and safety of polyacrylamide hydrogel injection ... (pmc.ncbi.nlm.nih.gov)
A Systematic Review of the Novel Compound Arthrosamid ... (esmed.org)
Choosing advanced injection options for knee osteoarthritis (amsk.co.uk)

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Medical Disclaimer

This website provides educational and general information about knee symptoms, conditions, and treatments. The content is for informational purposes only and does not constitute medical advice, diagnosis, or a treatment plan. It should not be used as a substitute for a professional consultation, examination, or clinical decision-making by a qualified orthopaedic specialist.

If you are experiencing symptoms or are concerned about a knee problem, please arrange a clinical consultation. If you have urgent symptoms, severe pain, or are unable to put weight on your leg, please read our urgent advice guidance or contact emergency services immediately (dial 999 or NHS 111).