Two injections, two different jobs

Patients comparing ChondroFiller and Arthrosamid often arrive at the same question: which one is better? The more useful answer is that they are not rivals — they are designed for different stages of hip joint disease and do entirely different jobs.

ChondroFiller is a collagen scaffold that works with the hip's own biology to support repair within a focal area of cartilage loss. Arthrosamid is a permanent hydrogel that cushions a hip joint where diffuse wear has already progressed beyond the point where biological repair is realistic. One is a regenerative pathway; the other is a palliative one. Neither can do what the other does.

The decision between them is therefore driven by the pattern and extent of cartilage damage in your hip, not by personal preference or price. Both are delivered as ultrasound-guided outpatient injections at Lincolnshire Hip, and neither is available on the NHS or through private medical insurance — both are self-funded treatments.

What ChondroFiller does in the hip joint

ChondroFiller is made from acellular Type I collagen — a structural protein the body already recognises — injected into the hip joint as a liquid that gels in place over the worn cartilage surface. The material carries no living cells of its own. What it does instead is create a physical environment into which the patient's own progenitor cells can migrate from the surrounding tissue and begin repair, a process known as acellular matrix-induced chondrogenesis. The practical translation: the scaffold supports the body's own repair processes rather than substituting a synthetic material for lost cartilage.

The patient profile that suits ChondroFiller best is someone with a focal hip cartilage defect — Grade III or IV — where the margins of surrounding cartilage are still reasonably healthy and the biology of repair remains viable. Early-to-moderate wear across a contained zone fits this picture. Diffuse, end-stage hip osteoarthritis does not; the scaffold needs something to anchor to and cells capable of responding to it.

Published outcome figures come primarily from knee studies, a known limitation worth stating plainly. The prospective post-market study by Jerosch et al. recorded a mean IKDC score improvement of 32.4 points sustained at three years, and MOCART imaging confirmed more than 80% defect filling — both figures exceeding the accepted minimum clinically important difference of 16.7 points. Extrapolation to the hip rests on a shared mechanism and documented multi-joint clinical use rather than a separate hip-specific RCT dataset.

Lincolnshire Hip prices ChondroFiller from £2,995 per box, inclusive of consultation, ultrasound imaging, the collagen scaffold, IV antibiotic cover, and a six-week follow-up — a broadly comparable self-funded commitment to Arthrosamid, which is covered in the section that follows.

What Arthrosamid does in the hip joint

Unlike ChondroFiller's regenerative goal, Arthrosamid takes a fundamentally different approach — managing symptoms rather than rebuilding tissue.

The hydrogel is composed of 2.5% cross-linked polyacrylamide and 97.5% water, making it non-biodegradable and non-resorbable in the joint. A single image-guided injection introduces the material into the hip joint space, where it adheres to the synovial membrane lining. Over the following 10 to 30 days, synovial cells infiltrate the gel through a low-level macrophage-driven process, forming a stable sub-synovial cushion layer that provides viscoelastic buffering across the joint surfaces. It does not attempt to repair or replace cartilage.

Arthrosamid holds CE approval for knee osteoarthritis, granted in 2021; its use in the hip is an extrapolation of the same mechanism to a different heavily loaded joint, without a dedicated hip RCT dataset. Patients considering this pathway should weigh that distinction carefully.

The clinical profile that suits Arthrosamid best in the hip is diffuse, KL Grade III–IV osteoarthritis — where cartilage loss is widespread, biological repair is no longer a realistic target, and the priority is meaningful symptom relief and joint preservation ahead of potential hip replacement. Published data, drawn primarily from knee studies, show pain reduction from around week 4, with average symptom relief of approximately two to three years from a single injection. A 2022 secondary analysis by Maulana, Cole, and Lee also recorded a reduction in bone marrow lesions following a single iPAAG injection — an interesting additional observation, though one that requires further investigation before firm conclusions can be drawn for the hip.

Because the hydrogel triggers a mild inflammatory response as it integrates into the synovial tissue, patients are advised to take NSAIDs for seven days post-injection — both to manage that response and to reduce infection risk during the immediate post-procedure period.

Which pathway fits which patient

For most patients, the clearest discriminator is the pattern of cartilage loss shown on MRI and graded using the Kellgren-Lawrence (KL) scale — not the severity of pain alone.

The ChondroFiller profile. Hip imaging showing a localised area of cartilage thinning or damage — where the surrounding cartilage retains reasonable integrity and the joint space is not globally collapsed — points towards a regenerative scaffold pathway. Patients at earlier stages of hip osteoarthritis (broadly KL Grade I–II, or a contained Grade III focal defect) who are prepared to support a biological repair process over several months tend to be the strongest candidates.

The Arthrosamid profile. Where cartilage loss is diffuse rather than focal, and MRI or X-ray suggests KL Grade III–IV hip osteoarthritis across the joint, the clinical priority typically shifts to durable symptom management. Arthrosamid may suit patients who want meaningful relief from pain and functional decline while deferring — or reconsidering — hip replacement, rather than pursuing tissue repair.

The two injections are not mutually exclusive in principle, but they serve different roles and should not be treated as equivalent. Choosing between them requires imaging review and clinical assessment: a diagnosis made on symptoms alone is unlikely to identify the right pathway.

Lincolnshire Hip accepts patients without referral and can review existing imaging as part of a hip assessment to help clarify which option, if either, is appropriate.

Honest gaps in the evidence

One gap that sits outside both product profiles is worth naming plainly: no published trial has compared ChondroFiller and Arthrosamid directly — in the hip or in any other joint. The choice between them is therefore built on disease-stage logic and clinical assessment, not on head-to-head efficacy data.

That distinction matters when setting expectations. The outcome figures cited in clinical settings come from knee studies and are extrapolated to the hip on the basis of shared synovial joint anatomy and multi-joint clinical experience. Extrapolation of this kind is supported by mechanistic reasoning, but 'promising results from knee data' is not the same as 'proven outcomes in the hip', and an honest clinician will say so at consultation rather than present knee figures as hip guarantees.

Neither treatment is experimental in the ordinary sense: both are CE-marked devices in active clinical use across multiple joint sites. The better framing is that the evidence base is maturing — hip-specific data are accumulating but have not yet reached the trial-level rigour that would allow blanket guidance for every patient. That is why imaging review and individual assessment remain the only reliable basis for a pathway recommendation, and why neither product can responsibly be positioned as the right answer for all patients with hip pain.

Starting the conversation at Lincolnshire Hip

Both pathways are available at Lincolnshire Hip as ultrasound-guided outpatient appointments, with access points in Sleaford and Grantham covering patients across Lincolnshire and the wider East Midlands.

A first appointment typically begins with imaging review — ideally a recent MRI of the hip — to characterise whether cartilage loss is focal or diffuse. That distinction is the practical question the assessment is designed to answer. Where imaging is not yet available, the clinical team can advise on what is needed before a pathway recommendation can be made.

On the practical side, both ChondroFiller and Arthrosamid are self-funded treatments — neither is available through the NHS or reimbursed by private medical insurers such as Bupa or AXA — so costs are worth discussing at the outset of any consultation rather than after a recommendation has been formed.

Lincolnshire Hip is part of the MSK Doctors group and accepts patients without referral for hip assessment.