How long each treatment lasts, answered directly

Three treatments, three very different time horizons — and knowing the rough figures before diving into the science helps frame the decision.

Hyaluronic acid (HA) injections typically ease symptoms for around six months. Without a repeat course, relief returns to baseline; most patients receiving products such as Durolane, Ostenil, or Synvisc on a long-term basis schedule injections roughly every six months to maintain effect.

Arthrosamid® lasts considerably longer. Published clinical data show an average of two to three years of symptom relief from a single injection, with studies confirming sustained relief for at least 12–24 months. Patient-reported accounts from sources including Nuffield Health and Benenden Hospital cite up to five years in some individuals, though the structured clinical floor is more conservatively 12–24 months.

ChondroFiller® operates on a different logic: the collagen scaffold is resorbed by one to two years, but the repair tissue it helped the body build continues beyond that point. London Cartilage Clinic and AMSK report outcomes maintained at three to five years in suitable patients.

No direct head-to-head randomised trial comparing all three treatments currently exists; these figures come from separate cohort and post-market clinical follow-up studies. The next section explains why the timescales differ so markedly — because each treatment works through an entirely different mechanism.

Why these treatments last different lengths of time

The durability differences follow directly from what each treatment does inside the joint — three distinct biological fates, not simply three points on a timeline.

Hyaluronic acid is metabolised by the body in much the same way as naturally occurring joint fluid. It lubricates, dampens pain signalling, and is then absorbed — leaving no structural change to the joint surface. Once it clears, the mechanical and biochemical environment reverts to what it was before, which is why symptom relief fades and repeat courses are required every six months or so.

Arthrosamid® follows a different path. As a non-biodegradable polyacrylamide hydrogel, it is not absorbed and remains in the joint long-term, integrating with the synovial lining. This is a mechanical, padding mechanism — Arthrosamid does not recruit cells or support any repair of the cartilage surface itself. Its duration reflects continued physical presence, not biological change.

ChondroFiller® works differently again. Once placed under ultrasound guidance, the acellular collagen scaffold sets in situ within minutes and begins recruiting the patient's own progenitor cells from surrounding tissue — a process known as matrix-induced chondrogenesis. Over roughly twelve months, those cells progressively lay down new repair tissue; by one to two years the scaffold is fully resorbed. Durability here does not depend on the scaffold remaining — it comes from the endogenous repair tissue the patient's own cells produced during that window. The scaffold is the means; the sustained benefit is the end.

That distinction matters for decision-making: Arthrosamid® provides cushioning; ChondroFiller® supports the body's own repair processes. These are different therapeutic goals, and the timescales reflect that.

ChondroFiller's repair timeline: what the evidence shows

Tracking ChondroFiller's trajectory from the moment of injection helps explain why the multi-year outcomes reported by some clinics are a consequence of what the scaffold sets in motion, not a marketing claim.

At the point of ultrasound-guided placement, the liquid collagen solution gels within three to five minutes, conforming to the defect site. Within days to weeks, the patient's own cells — drawn from the surrounding synovium and subchondral bone — begin migrating into the matrix. A 2025 ex vivo study recorded a 2.4-fold increase in scaffold DNA content by day 14, providing direct laboratory evidence that this cell migration is measurable rather than theoretical.

The most clinically meaningful way to track what follows is through IKDC scores — a validated patient-reported measure of knee function. The Jerosch et al. prospective post-market clinical follow-up (PMCF) study showed a mean improvement of 32.4 IKDC points, with patients reaching a score of 80. Crucially, that improvement was maintained and very slightly increased at three-year follow-up, rather than fading — the repair tissue the scaffold had enabled continued to function long after the scaffold itself was gone. Structural imaging reinforces this picture: MOCART scores (measuring defect filling and tissue integration) rose from 65.3 at four weeks to 81.6–84.3 at twelve months, indicating more than 80% defect filling by one year as cells matured within the matrix.

By one to two years the collagen scaffold is fully resorbed, yet functional gains persist because the scaffold is no longer load-bearing — the patient's own repair tissue is. London Cartilage Clinic and AMSK report outcomes maintained at five years and beyond in suitable patients. These are clinic-level findings from post-market follow-up cohorts, not large randomised controlled trials, and should be read in that context. They do, however, align with the biology: once adequate repair tissue has formed, it is the patient's own cartilage — not the original implant — that sustains relief.

Arthrosamid and hyaluronic acid: what the duration data shows

The published figures for Arthrosamid® span a wider range than those for either comparator, and understanding the source of that range is the most useful thing this section can add beyond what the opening summary already set out.

Structured clinical outcome data — including the series reported by Professor Ali Ghoz and the cohort data published by London Cartilage Clinic — support at least 12–24 months of sustained relief from a single injection, with published outcome averages of two to three years. The upper-end figures of four to five years, cited by institutions such as Nuffield Health and Benenden Hospital, derive primarily from patient-reported outcomes and manufacturer-aligned sources rather than from independent controlled trials; that distinction is worth carrying into any comparison. Where relief does eventually diminish, a repeat procedure is possible, but the interval between courses is measured in years rather than months — a practical difference from any six-monthly injection schedule.

Hyaluronic acid: consistent evidence, contested guidelines

For HA, the duration picture is more uniform. Across published evidence, symptom benefit lasts approximately six months, after which UK clinicians — using products such as Durolane, Ostenil, Synvisc, and Hyalgan — typically schedule a further course to maintain comfort. Without re-injection, relief returns to baseline within six to twelve months. HA acts on the joint environment rather than the cartilage surface; it does not fill or structurally alter a focal defect. On clinical guidelines, OARSI offers conditional support for viscosupplementation in knee osteoarthritis, while AAOS and ACR are more sceptical — a disagreement that reflects both the modest average effect size across populations and variability between HA preparations and patient profiles.

What shapes how long results last

Several variables moderate how long any of these three treatments holds — and they do not act equally across all three options.

• Osteoarthritis severity. More advanced joint degeneration tends to shorten the window of benefit from any injection-based treatment, because the underlying disease process continues regardless of what has been placed in the joint.
• Defect size and location. ChondroFiller is indicated for focal cartilage defects; larger or diffuse lesions present a more challenging biological environment for cell migration than a contained, well-defined focal defect does.
• Patient activity level. High-impact loading can accelerate wear on both repair tissue and hydrogel cushions. Returning gradually to appropriate activity — rather than immediately resuming heavy sport — is relevant for all three treatment types.
• Age and cell biology. Because ChondroFiller's mechanism depends on the patient's own progenitor cells migrating into the scaffold, individual variation in that biological capacity can influence how completely the defect fills and how durable the repair tissue proves to be. This factor is less directly relevant to Arthrosamid or HA, which do not rely on cell recruitment.

These variables interact rather than operate in isolation. A patient with a moderate focal lesion returning to low-impact activity sits in a very different position from one with diffuse disease continuing high-impact sport — and the treatment that best matches the first may not suit the second at all. Imaging and clinical assessment are how that distinction gets made.

Finding a specialist who offers ChondroFiller

Choosing a specialist for any of these treatments starts with whether they have the training and equipment to assess cartilage defects accurately — and for ChondroFiller specifically, that includes experience reading cartilage imaging and grading osteoarthritis severity, not just administering the injection itself. The procedure is delivered as an ultrasound-guided outpatient injection; no hospital admission is required for the treatment.

Availability varies across the UK. ChondroFiller and related injection therapies are offered by orthopaedic and sports medicine specialists in both major cities and regional centres, though the subspecialty focus and imaging capability needed to assess suitability are not universal. Search MSK lists UK specialists who offer ChondroFiller and related injection therapies — the region and specialty filters help identify one whose practice matches both the treatment and the patient's location.