Two injections, two different problems

The most common question patients bring to a first consultation is whether ChondroFiller and Arthrosamid are broadly the same thing under different brand names. They are not — and understanding why that matters is the starting point for any useful comparison.

ChondroFiller is an acellular natural collagen scaffold, manufactured by Meidrix Biomedicals GmbH in Germany. Delivered under ultrasound guidance as an outpatient injection, it coats the load-bearing cartilage surfaces of the joint and invites the body's own progenitor cells to migrate in and begin rebuilding tissue through a process called matrix-induced chondrogenesis. Its target is the cartilage surface itself — the structural layer that erodes in osteoarthritis and focal cartilage injury.

Arthrosamid is a different material entirely: a permanent, non-absorbable polyacrylamide hydrogel (iPAAG) made by Contura A/S in Denmark. Also given as a single ultrasound-guided injection, it works within the synovial space — the lining of the joint — to modulate the inflammation (synovitis) that is closely linked to pain in knee osteoarthritis. It does not attempt to restore the cartilage surface.

One injection addresses structural loss at the joint surface; the other addresses inflammatory pain driven by the joint lining. Whether one, the other, or elements of both are relevant depends entirely on which of those two pathological processes is dominant in a particular knee.

Which patients are suited to each pathway

Eligibility for either injection follows the pathology rather than the patient's age or general fitness level — but the two products diverge sharply in where they can be used and what clinical picture they suit.

ChondroFiller carries no upper age limit and no ceiling on defect size, because the collagen scaffold does the protective work across the whole joint surface without requiring the body to mount a large-volume regenerative response. Crucially, it is licensed across eight joints — knee, hip, shoulder, ankle, elbow, foot, hand, and wrist — making it the only option of the two for patients whose pain arises from cartilage damage outside the knee.

Arthrosamid, by contrast, is indicated specifically for symptomatic adult knee osteoarthritis in which synovitis is a significant driver of pain. It has not been approved for the hip, shoulder, or any other joint. A patient with focal cartilage loss in the ankle or a worn hip is straightforwardly outside its licensed scope.

Within the knee, the distinction sharpens further. Where imaging reveals predominantly surface cartilage erosion with limited synovial involvement, ChondroFiller's scaffold mechanism targets the dominant problem directly. Where the cartilage surface is relatively intact but the joint lining is inflamed and painful, Arthrosamid's mechanism aligns more closely with what is driving the symptoms. When both pathology types coexist, that opens a different conversation — covered in a later section.

The determining factor in all cases is which pathological process is dominant: that determination relies on structured clinical review and imaging, and it is the step that shapes everything that follows. For patients whose damage spans more than one joint, ChondroFiller's multi-joint licensing is a practical advantage that Arthrosamid simply cannot match.

What each appointment looks like in practice

Patients who have only encountered joint treatment in the form of an operation are often surprised by how straightforward both appointments are in practice.

ChondroFiller and Arthrosamid are each given as outpatient, ultrasound-guided injections under local anaesthetic. There is no surgical incision, no general anaesthetic, and no overnight stay; patients leave the clinic the same day in both cases.

A ChondroFiller appointment runs approximately 30 to 45 minutes. The procedure includes real-time image-guided placement of the collagen scaffold, intravenous antibiotic cover as a precautionary measure, and a six-week follow-up appointment to monitor how the joint is responding.

Arthrosamid is administered as a single injection, also under ultrasound guidance. Published clinical data — including Bliddal et al.'s 2024 open-label study in the Journal of Orthopaedic Surgery and Research and a 2021 prospective study — suggest that one injection may provide sustained pain relief for up to three years in suitable patients, though individual results vary.

The difference in aftercare reflects the difference in mechanism: ChondroFiller's scaffold needs time to recruit the body's own cells and support tissue repair, so the structured follow-up period is part of the therapeutic plan; Arthrosamid's permanent hydrogel is intended to remain in place from the outset, with the single session representing the full procedural commitment.

What the clinical evidence shows for each

The evidence supporting each injection sits in different research contexts — and that difference matters when weighing what the data can and cannot tell us.

For Arthrosamid, the published record includes Bliddal et al.'s 2024 open-label study in the Journal of Orthopaedic Surgery and Research, which confirmed effectiveness and safety at 12-month follow-up, alongside a 2021 prospective study reporting 6-month outcomes. London Cartilage Clinic has contributed to published 24-month outcome research and has now administered more than 1,200 injections — a volume that adds meaningful real-world confidence alongside the trial data. The evidence base is predominantly open-label and observational, however, which is a limitation shared by most interventional studies at this stage of device adoption.

ChondroFiller's injection-pathway evidence is less extensively published than the literature behind its surgical scaffold form — a point worth noting plainly. Available outcome data from clinical series show approximately a 30-point improvement on the IKDC knee scoring scale, MOCART scores in the 70–87 range, and a reported complaint rate of around 0.06%. These figures indicate a meaningful clinical response in suitable patients, though they derive from series rather than large randomised controlled trials.

No head-to-head RCT comparing ChondroFiller directly against Arthrosamid exists. Ranking one above the other on the basis of published volume alone would therefore be misleading: the two products have been studied in different populations, targeting different parts of the joint pathology. Whichever injection carries the larger dataset at any given moment, that metric cannot determine which is appropriate for a specific joint — because the question each product answers is not the same one.

When both injections are used together

The combination pathway — referred to as CFI+ — applies to a specific clinical situation: a knee in which both meaningful cartilage surface loss and confirmed synovitis are present. In that scenario, ChondroFiller and Arthrosamid are used sequentially, with ChondroFiller delivered first to lay the collagen scaffold over the worn surface, and Arthrosamid given at a separate, spaced appointment to address the synovial inflammation driving pain. The two products are never given in the same session; each targets a distinct part of the pathological picture, and their mechanisms do not overlap.

CFI+ is not a default upgrade from either injection used alone. A patient whose knee is acutely inflamed without confirmed cartilage loss would not be a candidate — Arthrosamid is not added simply because swelling or flares are present. The sequential plan is driven by the confirmed co-existence of both pathology types, not by symptom severity alone.

Direct evidence for the combined approach is limited at this stage; the rationale draws on the established individual mechanisms of each product and on careful clinical evaluation of co-existing pathology, rather than on trial data specific to the paired sequence.

For joints with very heavy wear, a further escalation exists: CFI++, in which the patient's own mesenchymal stem cells are incorporated into the ChondroFiller preparation to increase the regenerative signal. Starting from approximately £10,500, CFI++ represents the most intensive injection-pathway option for severely compromised joint surfaces — a step beyond what either product, or the CFI+ combination, can offer on its own.

Cost, access, and booking without a referral

The pricing picture for both pathways is broadly similar: guide costs start from approximately £3,000 for a single injection, rising with the number of boxes required or with escalation to CFI++. Neither ChondroFiller nor Arthrosamid is NHS-funded, and neither is routinely covered by private medical insurance. That symmetry matters because it removes cost as a practical differentiator — patients who try to decide between the two on financial grounds alone are starting from the wrong question. The clinical picture is what separates one pathway from the other, and guide costs are confirmed at the point of booking rather than read from a fixed list.

For patients outside London, MSK Doctors accepts referrals from GPs and self-referrals alike, with no NHS-style waiting list. Consultations are available at Sleaford in Lincolnshire and at Grantham, both of which support on-site imaging review as part of the assessment process.

Ultimately, the comparison between ChondroFiller and Arthrosamid is not a question of preference, price, or which product carries the longer published history. They treat different tissues, through different mechanisms — surface cartilage loss on one side, synovial inflammation on the other. Matching the injection to what the joint actually shows is the only question the comparison hinges on. Patients can book an initial consultation, without a referral, at mskdoctors.com.