Can both cartilage damage and joint-lining inflammation be treated in one injection visit?

For patients told that their hip has both worn cartilage at the bone ends and chronic inflammation of the joint lining, the immediate concern is often whether that means two separate procedures on two separate occasions. The short answer is no.

The Dual-Active protocol delivers two distinct ultrasound-guided injections within a single outpatient appointment: a ChondroFiller injection (2.3 mL), which places an acellular collagen scaffold directly over the degenerated articular surfaces, followed by Arthrosamid (6 mL), which is introduced to the synovial lining. Each product targets a different anatomical compartment — they are not blended, and they should not be treated as interchangeable. ChondroFiller injection is the regenerative component; Arthrosamid addresses the inflamed joint lining. Both roles matter in advanced hip osteoarthritis, which is why the combination exists.

The protocol is indicated for Kellgren-Lawrence Grade III or IV hip osteoarthritis — the stage sometimes described as the 'impossible joint' because it sits beyond the reach of most single-product injection strategies. There is no theatre booking, no general anaesthetic, and no surgical incision. The session takes place at the London Cartilage Clinic on Harley Street, the UK's certified delivery centre for ChondroFiller injection.

The guide cost for the Dual-Active combination is £6,000, as confirmed by the clinic — a single bundled fee covering both injections in one visit.

Why advanced hip OA produces two separate pain sources

Two things tend to go wrong at once in advanced hip osteoarthritis, and they hurt for different reasons.

The first is articular cartilage loss. As the cartilage covering the femoral head and acetabulum wears through, load passes directly to the underlying subchondral bone. That generates the deep, weight-bearing pain that worsens with walking or standing — and, in time, contributes to bony oedema within the joint.

The second is synovial inflammation. The joint lining — the synovium — becomes hypertrophied and irritated, releasing inflammatory mediators into the joint space. This process is largely independent of mechanical load, which is why many patients with advanced hip OA also experience aching at rest, overnight stiffness, and swelling that persists even when they are sitting still.

Most single-agent injections address one of these compartments but not both. Hyaluronic acid improves lubrication at the articulating surfaces; corticosteroid reduces acute synovial flare; standard PRP may support tissue repair but does not provide durable synovial buffering. Each has a role, but each leaves at least one pain source unaddressed.

By Kellgren-Lawrence Grade III or IV, both compartments are commonly involved. That is the anatomical justification for the combination approach. The treatment hierarchy reflects this: HA offers lubrication only; Arthrosamid alone provides synovial pain dampening; ChondroFiller injection alone provides a regenerative scaffold at the bone surfaces; the Dual-Active addresses both simultaneously; and Tri-Active adds autologous mesenchymal stem cells for the most complex presentations.

What ChondroFiller injection does at the bone ends

Applied to the worn articular surface under ultrasound guidance, the ChondroFiller injection works in two overlapping phases: an immediate mechanical one and a slower, cellular one.

The scaffold itself is an acellular Type I collagen extract (CE-marked Class III medical device, manufactured by Meidrix Biomedicals GmbH in Germany). On contact with the articular surface it gels in situ, coating the degenerated bone ends with a viscoelastic cushion that reduces bone-on-bone friction. This is the top-down mechanical effect — present from the moment of delivery.

The second phase unfolds over 6–12 months. The collagen matrix acts as a chemotactic signal, drawing the patient's own progenitor cells from the synovium and the subchondral bone into the scaffold, where they deposit new matrix. This process — matrix-induced chondrogenesis — requires no donor cells and no surgical preparation; the scaffold recruits repair capacity already present in the joint.

Because the ChondroFiller injection is delivered through a needle rather than placed arthroscopically, it has no defect-size ceiling and can coat the entire articular surface in one session. In hip osteoarthritis, where damage tends to be diffuse rather than a contained focal lesion, this is a practical advantage. There is also no upper age limit for the scaffold, making it applicable for patients well into their sixties, seventies, and beyond.

Published clinical data for ChondroFiller injection come predominantly from knee studies. The Jerosch et al. post-market clinical follow-up study recorded a mean IKDC improvement of 32.4 points at three-year follow-up — more than double the 16.7-point minimum clinically important difference — with patients reaching a mean functional score of 80. MOCART imaging scores between 81.6 and 84.3 confirmed greater than 80% defect filling and solid integration with native tissue. Hip-specific published data are sparse in the available literature; these knee figures represent the closest controlled evidence for the scaffold and are what clinicians draw on when advising hip OA patients.

What Arthrosamid does at the synovial lining

Where ChondroFiller injection works on worn cartilage at the bone ends, Arthrosamid operates on a different tissue altogether — the synovial membrane lining the joint capsule.

Arthrosamid is a 2.5% cross-linked polyacrylamide hydrogel (iPAAG) suspended in 97.5% non-pyrogenic water. Once injected, it is neither broken down nor absorbed: the hydrogel is non-biodegradable and non-resorbable, remaining in the joint indefinitely. It adheres to the synovial membrane, providing an immediate mechanical buffer against the inflammatory forces acting on the lining. Over time, a de novo layer of infiltrating synovial lining cells forms around the hydrogel matrix — a process documented by Henriksen et al. (2018) and Tnibar et al. (2017) — augmenting its buffering effect with a biological interface.

This is not a regenerative process in the same sense as matrix-induced chondrogenesis. Arthrosamid does not recruit progenitor cells to build new cartilage tissue; its primary function is mechanical pain dampening at the synovial compartment, independent of what is happening at the articular surface.

European regulatory approval was granted in 2021 for knee osteoarthritis following a clinical study demonstrating significant pain reduction; use in the hip extends that indication to a joint with broadly comparable synovial anatomy. Symptom relief has been documented out to three years in knee OA populations. A published case series by Maulana, Cole, and Lee (Journal of Arthritis, 2022) reported reduction in patellofemoral bone marrow lesions following a single iPAAG injection — a structural signal that may indicate benefit beyond symptom relief alone, though this finding requires further investigation before firm conclusions can be drawn.

What the single clinic visit involves

The appointment takes place at London Cartilage Clinic on Harley Street as a single outpatient session — patients arrive, are treated, and leave the same day without hospital admission.

Both injections are delivered under continuous ultrasound guidance, which allows the clinician to confirm accurate placement in real time. The sequence follows the anatomy: the ChondroFiller injection (2.3 mL) is placed first onto the worn articular surfaces at the bone ends, where it gels in situ. Arthrosamid (6 mL) is then delivered into the synovial compartment. Treating the articular surface before the synovial lining preserves a clear image plane for each stage and ensures neither product disturbs the other's placement.

The two components work on different timescales once delivered. Arthrosamid's mechanical buffering effect at the synovial lining is present from the outset. ChondroFiller injection's matrix-induction effect is slower — the collagen scaffold requires 6–12 months for host progenitor cells to migrate in and deposit new matrix, so improvements from that component accumulate gradually rather than appearing immediately.

Professor Paul Y.F. Lee leads the programme at London Cartilage Clinic, which operates as an ICRS Teaching Centre of Excellence.

For patients with more extreme joint deterioration, a Tri-Active escalation adds autologous mesenchymal stem cells — harvested from bone marrow, fat, or ear cartilage — as a third component in the same session, at a total cost of £11,000. Whether this escalation is appropriate is determined at the initial assessment, not at the treatment visit itself.

Who is a suitable candidate and how to get an assessment

The patients most likely to benefit are those who have already been told — often by an orthopaedic surgeon — that their hip osteoarthritis is too advanced for standard injections, typically Kellgren-Lawrence Grade III or IV, but who wish to avoid or defer total hip replacement. On imaging, suitable candidates generally show both articular cartilage loss at the load-bearing bone ends and synovial inflammation: the two-compartment picture that each injection directly addresses.

There is no upper age limit. Suitability is assessed against anatomy, residual joint space, and overall health at consultation rather than against chronological age — active patients in their sixties, seventies, and beyond are evaluated on the same clinical criteria.

On the evidence: each component carries its own published record, with prospective data and outcomes documented out to three years. What does not yet exist is a randomised controlled trial of the Dual-Active combination specifically in the hip. The current evidence base draws on single-arm prospective knee studies, manufacturer post-market clinical follow-up data, and a published bone-marrow-lesion case series — meaningful building blocks, but independent RCT validation in the hip is absent. That distinction is worth naming plainly rather than glossing over.

Equally, this protocol is not the right answer for every patient with Grade III/IV hip OA. For some, hip replacement is the more appropriate next step, and a thorough clinical assessment will say so.

Initial assessments are available at London Cartilage Clinic on Harley Street (londoncartilage.com). A useful question to raise at that appointment: how does the published knee outcomes data translate to your specific degree of hip involvement? That conversation — rather than imaging reports alone — is where realistic expectations take shape.