Which injection fits which type of hip cartilage damage

The type of hip cartilage damage — not the severity of pain alone — determines which of these two injections is clinically appropriate.

ChondroFiller is a regenerative collagen scaffold suited to focal, well-bordered Grade III/IV cartilage defects in a hip joint where the overall joint space remains reasonably preserved. It works by recruiting the patient's own cells to begin repair within a localised lesion. Arthrosamid is a non-biodegradable polyacrylamide hydrogel that acts as a permanent mechanical cushion; its licensed indication is knee osteoarthritis, and its use in the hip remains off-label.

A younger, active patient with a discrete patch of full-thickness cartilage loss — and healthy surrounding tissue — is typically the profile for ChondroFiller. A patient with more diffuse, advanced hip degeneration, where the joint surface has worn broadly rather than in one isolated spot, is more likely to be considered for a cushioning agent such as Arthrosamid, used here outside its licensed pathway.

Both treatments are delivered as ultrasound-guided outpatient injections under local anaesthesia in the current service pathway. Patient selection, based on imaging and clinical assessment, drives the decision — neither product is appropriate for every hip or every stage of cartilage loss.

How ChondroFiller works as an injectable hip scaffold

ChondroFiller (Meidrix Biomedicals, Germany) is a CE-marked Class III medical device: a purified, acellular Type I collagen hydrogel supplied in a ready-to-use two-chamber syringe. Delivered as an ultrasound-guided outpatient injection under local anaesthesia, the gel self-sets within approximately 3–5 minutes at body temperature, forming a three-dimensional matrix directly over the defect site within the hip joint.

Its mechanism is acellular matrix-induced chondrogenesis. The injected scaffold contains no living cells; instead, it supports the body's own repair processes by recruiting the patient's own progenitor cells from the surrounding synovium and subchondral bone. Over 3–6 months, those recruited cells progressively remodel the scaffold into fibrocartilage-like repair tissue as the collagen matrix gradually resorbs. This timeline matters clinically: patients should expect benefits to develop as repair tissue matures, not immediately after injection. That distinction separates ChondroFiller clearly from corticosteroid injections — which reduce inflammation acutely but provide no structural scaffold — and from hyaluronic acid, which temporarily lubricates the joint without promoting endogenous repair.

For the hip specifically, a 2021 publication by Perez-Carro et al. confirmed that ChondroFiller is a viable option for full-thickness acetabular cartilage defects, particularly anterosuperior lesions associated with cam-type femoroacetabular impingement (FAI). Aggregate data from pooled clinical series — not a single peer-reviewed RCT — suggest that roughly 70–85% of treated patients achieve meaningful functional improvement, with Harris Hip Score gains averaging approximately 33 points sustained at 3–5 year follow-up, and reoperation rates of around 3–8%. These figures are indicative rather than definitive and should be read accordingly.

The product is licensed for Grade III and IV cartilage damage across multiple joints including the hip. Its evidence and regulatory base are European; it is not FDA-approved in the United States.

What Arthrosamid does in the hip joint

Unlike ChondroFiller's collagen scaffold, Arthrosamid (Contura International) acts on the joint's lining rather than on a cartilage defect itself. Composed of 2.5% cross-linked polyacrylamide and 97.5% water, it integrates with the synovial tissue within 10–14 days through a low-level macrophage-driven foreign body response; by days 30–90 a stable sub-synovial gel layer forms, thickening the joint lining to provide a durable mechanical cushion. The hydrogel recruits no repair cells and initiates no chondrogenic process — its role is entirely mechanical rather than biological, which is a fundamental mechanistic distinction from ChondroFiller.

Because the material is non-biodegradable, a single injection is the intended treatment course. For the knee, this durability is well evidenced: Bliddal et al.'s 2025 five-year extension of the IDA trial confirmed sustained, clinically meaningful reductions in WOMAC pain and stiffness from one 6 ml injection, and 10-year observational safety data presented at WCO 2025 found no degradation of the material and no negative effect on residual cartilage. All of this evidence base is, however, knee-specific.

For the hip, the position is materially different. Arthrosamid is licensed for knee osteoarthritis only; its use in the hip joint is off-label, with no published randomised controlled trials and no regulatory approval covering hip application as of mid-2026. Some UK private MSK clinics offer it for hip pain, reasoning by analogy from knee data and citing approximately 80% symptom response in patients under 70. That comparison is reasonable as a working hypothesis, but it is extrapolation rather than hip-specific evidence.

The permanence of the implant is the central trade-off to consider. Regulatory assessments have flagged a theoretical concern around residual acrylamide monomer leaching from a permanent gel over time — acrylamide is classified as a neurotoxin and a suspected carcinogen — though long-term knee safety data have not identified this as a clinical problem in practice. For patients considering it for hip pain, private cost is typically in the range of £2,000–£3,000; it is not available on the NHS.

Matching the right injection to your hip damage pattern

Knowing which category applies to you comes down to two pieces of imaging, and understanding what clinicians are looking for in each.

A plain radiograph — a standing weight-bearing X-ray of the hip — tells the clinician how much joint space remains. Radiologists and surgeons grade this using the Kellgren-Lawrence (KL) scale, from 0 (no visible change) through to IV (severe narrowing with bone changes). KL grades I or II, where meaningful joint space is preserved, suggest the hip architecture is still worth protecting with a structural approach. KL grades III or IV indicate the joint space has narrowed substantially and the biological conditions that ChondroFiller's scaffold depends on — a viable progenitor-cell pool in the surrounding synovium and subchondral bone — are likely to be compromised. At that stage, neither injection is designed to restore what has been lost; the more honest conversation shifts toward managing symptoms ahead of hip replacement rather than repair.

An MRI scan adds the cartilage detail that plain X-ray cannot show: the precise location, depth, and borders of any defect, whether surrounding cartilage is healthy, and whether the subchondral bone beneath shows reactive change. It is this image that determines whether a defect is genuinely focal and well-bordered — the prerequisite for a scaffold approach — or whether wear is diffuse across the joint surface.

The practical upshot before a consultation: if you have imaging already, note the KL grade on the report and bring the MRI. If you have neither, an assessment appointment will establish which scans are needed before any injection is considered.

What each treatment involves and when benefits arrive

Both injections are carried out as ultrasound-guided outpatient appointments — no general anaesthetic, no overnight admission, no theatre. That shared procedural setting is worth stating plainly, because patients sometimes arrive expecting a hospital stay.

On the day

For ChondroFiller, the collagen scaffold is placed directly over the cartilage defect under real-time imaging. The appointment is typically complete within an hour, including the scan-guided placement. The hip will not feel meaningfully different on the way home — the mechanism is a slow-build one, and expecting early pain relief is the most common source of patient disappointment. Measurable functional improvement typically develops over several months as the patient's own biology interacts with the scaffold, so clinicians generally ask patients to give it that full timeframe before judging the result.

For Arthrosamid (used off-label at the hip), the injection timeline is different in character: most patients who respond do so within weeks rather than months, and the effect is intended to persist over multiple years from that single injection. As noted in the earlier section on mechanism, all published durability data for this product comes from knee studies, so how predictably this timeline translates to the hip joint remains an open question.

Post-injection, clinicians typically advise a short period of reduced loading on the hip for both pathways; specific guidance will depend on the treating clinician and individual factors.

Cost and access

Neither treatment is available on the NHS; both are self-pay. Arthrosamid pricing for hip use was covered above. ChondroFiller is also a self-pay procedure in the UK, and published pricing is not available — the treating clinic will confirm costs at assessment. No direct head-to-head trial has yet compared these two injections in the hip joint.

Hip assessment at Lincolnshire Hip

Choosing between these two injections — or identifying an entirely different pathway — begins with a structured hip assessment rather than a product preference. Defect type, Kellgren-Lawrence grade, and MRI findings all need to be in hand before a consultant can determine whether ChondroFiller's scaffold approach, off-label Arthrosamid, or an alternative is appropriate for that specific hip.

Lincolnshire Hip accepts patients without a GP referral at its Sleaford and Grantham clinics. As part of the MSK Doctors group, it offers consultant-led review of imaging and a clear next step — whether that leads to an injection pathway or elsewhere.