What is Arthrosamid?
Arthrosamid is a single-injection treatment for knee osteoarthritis. It is a soft hydrogel made of 2.5% polyacrylamide and 97.5% water, injected into the knee under ultrasound guidance. Instead of being broken down, the gel integrates with the joint lining, cushioning the knee and easing pain and stiffness. Clinical studies have followed patients for several years after one injection.
Considering treatment? See our Arthrosamid injection in Manchester page for suitability, the procedure and cost.
Definition and History of Development
Arthrosamid is an advanced intra‑articular treatment designed to alleviate symptoms of osteoarthritis by restoring joint cushioning and reducing pain.
First introduced in Denmark in the mid‑2010s, it emerged from research into polyacrylamide hydrogels—a class of materials long used in medical and cosmetic applications for their biocompatibility and stability.
Originally developed to provide a long‑lasting joint filler, Arthrosamid received CE marking (in 2021) following clinical trials that demonstrated both safety and efficacy.
Since then, it has been adopted by a growing number of specialist clinics across the UK and Europe as a minimally invasive option for patients with mild to moderate osteoarthritis who seek an alternative to traditional injectables or who wish to delay surgical intervention.
Composition: Polyacrylamide Hydrogel Properties
At its core, Arthrosamid consists of a cross‑linked network of polyacrylamide polymers suspended in a sterile aqueous solution.
This hydrogel mimics the viscoelastic properties of natural synovial fluid, providing both shock‑absorbing cushioning and smooth joint gliding.
Unlike some earlier hydrogels, the polyacrylamide matrix in Arthrosamid is non‑degradable and remains stable within the joint synovial membrane for extended periods—often two to five years
Its high water‑binding capacity helps maintain tissue hydration, while the uniform particle size ensures even distribution throughout the joint space, reducing the risk of lumpiness or uneven joint surfaces.
How Arthrosamid Differs from Other Injectables
While corticosteroids and hyaluronic acid have been mainstays of injectable osteoarthritis treatments, Arthrosamid offers several distinctive advantages.
Corticosteroids chiefly target inflammation and deliver rapid—but often short‑lived—relief, typically lasting a few weeks to months.
Hyaluronic acid supplements joint lubrication and may provide benefit for up to six months, but its effects can vary depending on formulation and patient factors.
In contrast, the polyacrylamide hydrogel in Arthrosamid serves as a semi‑permanent spacer, cushioning the joint over a much longer duration without the need for frequent repeat injections.
Furthermore, because Arthrosamid does not rely on biological molecules, it carries a lower risk of inflammatory reactions or degradation by native enzymes, offering a stable, consistent effect that can help bridge the gap between conservative therapies and eventual surgical options.
Intra‑articular Cushioning and Shock Absorption
Arthrosamid’s polyacrylamide hydrogel formulation acts as an internal buffer, restoring much of the lost cushioning within a degenerated joint. When injected, the gel fills microscopic fissures and resurfacing irregularities, creating a smooth, continuous layer that separates the opposing bone surfaces.
This viscoelastic barrier disperses mechanical loads more evenly during weight‑bearing activities such as walking or climbing stairs, thereby reducing peak stresses on focal areas of exposed bone.
Patients often report a marked reduction in grinding sensations and a more natural “give” within the joint, which translates into easier movement and less discomfort during daily tasks.
Longevity of Hydrogel Within the Joint Space
One of Arthrosamid’s most compelling attributes is its durability. Unlike hyaluronic acid preparations, which are gradually broken down by native enzymes and cleared from the joint within months, the cross‑linked polyacrylamide network remains stable for anywhere from two to five years.
Its non‑degradable nature means the gel maintains its volume and mechanical properties without the need for frequent retreatment. The material eventually becomes integrated with peri‑articular soft tissues, further anchoring it in place and ensuring consistent performance.
This lasting effect offers patients a prolonged window of symptom relief, allowing them to engage in rehabilitative exercise programmes and lifestyle modifications without recurrent flares.
Clinical Evidence & Efficacy
Key Clinical Trials and Their Outcomes
A pivotal multi‑centre study evaluated a single 6 mL Arthrosamid injection in patients with knee osteoarthritis.
At six months, participants experienced significant improvements in pain, stiffness and function, as measured by standardised osteoarthritis indices; these gains persisted at 12 months and were sustained out to two years. Three‑year follow‑up data confirmed durable pain reduction with no serious device‑related adverse events.
Comparative Studies Versus Placebo and Alternative Treatments
A systematic review of polyacrylamide hydrogels, including Arthrosamid, showed superior outcomes compared with hyaluronic acid at 52 weeks, with greater mean reductions in both pain scores and functional disability.
Although head‑to‑head randomised trials are limited, existing data suggest that Arthrosamid’s non‑degradable matrix offers more prolonged relief than biologic viscosupplements, likely due to its stable presence within the joint.
Duration of Symptom Relief and Patient Satisfaction Rates
Long‑term follow‑up indicates that most patients maintain meaningful symptom relief for up to three years after a single injection.
Over 80 per cent report improved joint comfort and daily activity levels, with high satisfaction driven by the convenience of a one‑off treatment.
Transient, mild local reactions are the most common side effect, and no long‑term safety concerns have emerged.
Indications & Patient Selection
Appropriate Osteoarthritis Grades
Arthrosamid is most suitable for individuals with mild to moderate osteoarthritis, typically corresponding to radiographic grades II and III on the Kellgren‑Lawrence scale.
At these stages, sufficient cartilage remains to benefit from the hydrogel’s cushioning effect, yet symptoms are pronounced enough to warrant intervention beyond conservative measures.
Patients with very early disease (grade I) often respond well to lifestyle modifications alone, while those with advanced, end‑stage osteoarthritis (grade IV) may require surgical options for optimal relief.
Contraindications and Cautionary Scenarios
Treatment is contraindicated in the presence of active joint infection, systemic infection or known hypersensitivity to polyacrylamide.
Arthrosamid should also be avoided in patients with significant joint deformity or instability that might impair even distribution of the gel.
Caution is advised for individuals on immunosuppressive therapy or with poorly controlled diabetes, due to elevated risks of delayed healing or local complications.
Prior joint prostheses do not categorically preclude treatment but necessitate a careful risk–benefit discussion.
The Arthrosamid Injection Procedure
The Arthrosamid injection procedure is quite straight forward, consisting of just 4 essential steps. Before the Procedure the doctor will assess your knee joint to determine whether Arthrosamid is suitable for you.
If it is suitable, then the first step is to clean the injection site.
Next the doctor will numb the area using a local anaesthetic to ensure the injection is as comfortable as possible.
The Doctor will then proceed to inject Arthrosamid into the knee, under Ultrasound Guidance, to ensure it is accurate.
Finally the doctor will apply a plaster on the injection site.
Immediate Post‑procedure Care and Activity Recommendations
After injection, patients are observed for 10–15 minutes to monitor for any acute reactions. Mild discomfort or a feeling of joint fullness is common and typically subsides within 24–48 hours. It is advisable to:
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- Rest the Joint Briefly: Avoid strenuous activities for 48 hours, but gentle range‑of‑motion exercises may commence once pain allows.
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- Ice and Analgesia: Apply an ice pack for 10–15 minutes at intervals to reduce swelling; simple analgesics such as paracetamol can be used if needed (avoid NSAIDs for 48 hours unless directed).
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- Gradual Return to Activity: After the initial rest period, patients are encouraged to resume low‑impact activities—such as swimming or cycling—and to follow any prescribed physiotherapy regimen to strengthen peri‑articular muscles.
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- Follow‑up Appointment: A review at 4–6 weeks allows the clinician to assess response, address any concerns and plan further rehabilitation or repeat interventions if necessary.
With meticulous technique and appropriate aftercare, the Arthrosamid injection procedure offers a safe, targeted approach to managing osteoarthritis symptoms and improving joint function.
Pain Reduction and Functional Improvement Timelines
Most patients begin to notice a reduction in joint pain within two to four weeks of receiving an Arthrosamid injection.
Initial improvements are often modest, as the hydrogel integrates and begins to restore cushioning; by six to eight weeks, however, many report a substantial decline in both activity‑related and resting discomfort.
Functional gains—such as easier stair climbing or walking longer distances—typically follow closely behind pain relief, with objective measures showing meaningful improvements in joint function by three months post‑injection.
These benefits tend to plateau thereafter, providing sustained relief for up to two-three years without the need for repeat treatments.
Impact on Joint Mobility and Daily Activities
By reinstating viscoelastic support within the joint, Arthrosamid not only eases pain but also enhances range of motion.
Patients frequently describe a smoother, more natural feel when bending or extending the treated joint, with reduced stiffness on waking and after periods of inactivity.
This restored mobility enables gradual return to favourite pastimes—gardening, hill walking or gentle exercise classes—that might previously have been curtailed by discomfort. Importantly, improved joint movement also helps to break the cycle of deconditioning, as stronger muscles better support the joint and further alleviate mechanical stress.
Patient‑Reported Quality‑of‑Life Enhancements
Beyond the physical benefits, Arthrosamid has a marked positive effect on overall well‑being. Surveys conducted alongside clinical trials reveal that over 80 per cent of patients experience better sleep quality, reduced reliance on oral pain medications and greater confidence in undertaking daily tasks.
Many highlight the psychological uplift that comes with regaining independence—returning to social activities, household chores and work responsibilities with less trepidation.
These holistic gains underscore how a single, minimally invasive treatment can deliver not only symptom control but also meaningful improvements in life satisfaction.
Risks, Side Effects & Safety Profile
Common, Transient Injection‑Related Reactions
It is not unusual to experience mild, short‑lived discomfort at the injection site. Patients often report a brief sensation of pressure or fullness as the hydrogel is introduced, alongside minor redness or swelling that typically resolves within 24–48 hours.
A small proportion may feel aching or stiffness in the joint for a day or two, which can generally be managed with simple measures such as rest, gentle icing and paracetamol.
These transient effects reflect the body’s normal response to a foreign material and, in most cases, settle quickly without the need for further intervention.
Rare but Serious Adverse Events
Although Arthrosamid boasts a strong safety record, very occasional serious complications have been reported.
Deep joint infection (septic arthritis) is the most significant concern, manifesting as increasing pain, warmth, fever or reduced range of motion in the days following injection.
Immediate medical attention is essential in such instances to prevent joint damage.
Hypersensitivity reactions are exceedingly rare, given the inert nature of polyacrylamide, but any signs of widespread rash, itching or breathing difficulty warrant urgent evaluation.
Implant migration or gel displacement has been documented in isolated cases, emphasising the importance of correct injection technique under imaging guidance.
Monitoring and Reporting Safety Concerns
Vigilant follow‑up underpins a robust safety profile. Clinics should provide clear instructions on recognising warning signs and ensure a point of contact for post‑procedure concerns. A review appointment around six weeks post‑injection allows the practitioner to assess efficacy and exclude evolving complications.
If infection or another serious issue is suspected, prompt joint aspiration, laboratory analysis and, if necessary, hospital‑based treatment will be instituted.
All adverse events are reported to the relevant regulatory bodies, contributing to ongoing pharmacovigilance and refinements in best practice.
Patients are encouraged to communicate any unexpected reactions promptly, thereby safeguarding both individual care and the broader evidence base for Arthrosamid.
Arthrosamid compared to other options such as Cortisone and Hyaluronic Acid
For a detailed comparison between Arthrosamid and other injections typically offered to resolve knee pain and improve knee function head over to our dedicated comparison page.
Typical Price Range per Injection in the UK
Want to know more about the price of Arthrosamid in Manchester? Click here for more information.
Private Pay Versus Insurance Coverage
Arthrosamid is regarded as an elective, self‑funded therapy. Most private health insurers in the UK do not cover polyacrylamide hydrogel injections for osteoarthritis, so patients should be prepared to meet the full cost out of pocket.
Patient Testimonials & Case Studies
Real‑world Success Stories
“I was sceptical at first, but within six weeks of my Arthrosamid injection I noticed a real difference,” recalls Sarah, a 62‑year‑old retired teacher with moderate knee osteoarthritis. “Walking the dogs used to be a painful chore; now I can cover over a mile without stopping.”
Before‑and‑After Functional Assessments
Objective measures often mirror patient reports. In one case series, average knee flexion improved from 100° to 120° at three months, while timed up‑and‑go tests decreased from 14 seconds to 10 seconds, signalling easier transitions from sitting to walking.
PAGE MEDICALLY REVIEWED BY DR AMIR AKHTAR JULY 2026
