Who is a suitable candidate for this treatment?

The clearest candidates are patients with an isolated, focal cartilage defect — typically Grade III or IV on arthroscopic grading — where the surrounding cartilage remains largely intact. A contained defect with healthy borders allows the injected collagen scaffold to anchor and integrate into neighbouring tissue; diffuse or end-stage damage, where cartilage has been lost across most of the joint surface, does not provide those conditions.

Two absolute contraindications apply for hip use: active joint infection, and end-stage hip arthritis in which cartilage has been entirely lost. Patients with widespread degenerative change throughout the joint, rather than a focal lesion, are unlikely to be suitable candidates.

Because the procedure is an ultrasound-guided outpatient injection carried out under local anaesthetic, many of the barriers associated with surgery — general anaesthetic, theatre admission, wound recovery — do not apply. Patients who might be considered too young for joint replacement, or who wish to defer an operative pathway, often fall within the assessment window.

MRI is a prerequisite before any injection is planned. Scans are used to map the defect, confirm its focal morphology, and identify any lesion patterns — such as very large or diffuse areas of damage — that would make scaffold placement unsuitable. A specialist will review that imaging as part of the candidacy assessment.

How ChondroFiller works inside the hip joint

The mechanism starts before the scaffold even forms. ChondroFiller Liquid — a CE-marked Class III medical device since 2013 — is composed of murine-derived Type I collagen, the same structural protein found in healthy articular tissue. At room temperature it remains a fluid; once injected into the joint space, it undergoes thermally triggered polymerisation at body temperature, solidifying in place into a three-dimensional collagen mesh.

That liquid-to-gel transition is what makes hip delivery possible without theatre conditions. The collagen does not need a surgically prepared, dry joint environment to adhere — it flows in as a fluid and gels where it lands, conforming to the contours of the defect. This is the property that allows an outpatient, image-guided placement to work in a deep ball-and-socket joint where open access would otherwise be required.

Once set, the scaffold does not simply occupy the space: it acts chemotactically, attracting the patient's own chondrocytes and mesenchymal progenitor cells from the surrounding synovium and subchondral bone. These cells migrate into the matrix, differentiate, and progressively deposit new tissue. Over three to six months, the collagen scaffold itself is gradually broken down and replaced — a process described as acellular matrix-induced chondrogenesis. What remains is fibrocartilage-like repair tissue generated by the body, not by the implanted material.

This is not cartilage regrowth in the sense of restoring pristine hyaline cartilage; the more precise description is that the scaffold supports the body's own repair processes by providing a temporary biological framework the joint can populate and remodel.

What the procedure involves from first appointment to recovery

Planning begins with MRI. Before any injection is booked, a specialist reviews cross-sectional imaging to map the cartilage defect, confirm its focal morphology, and rule out diffuse or end-stage damage that would make scaffold placement unsuitable. That scan also guides needle trajectory planning for the injection appointment.

On the day of treatment, no theatre admission is required. The procedure takes place in an outpatient clinic under local anaesthetic only. Because the hip is a deep ball-and-socket joint — inaccessible to unguided needling — image guidance is not a precaution but a clinical necessity. Ultrasound is the standard modality for needle placement into the joint space; fluoroscopy is a published alternative where ultrasound access is limited. The collagen scaffold is delivered in its liquid state through the guided needle and gels at body temperature within the joint, filling and conforming to the defect cavity.

After the injection, a protected-loading phase of four to six weeks follows. This is a normal and expected part of the process — not a complication — giving the gelled scaffold time to integrate with surrounding tissue before the joint is asked to bear full load. Patients are typically mobile during this period but avoid high-impact activity.

Repair tissue then matures progressively over three to six months as the body's own progenitor cells populate and remodel the scaffold. Functional improvement tends to track that biological timeline rather than appearing immediately after injection.

What the clinical evidence shows

Published outcome data for ChondroFiller come predominantly from multi-joint European studies, and the strongest evidence sits at that broader level. Across knee, shoulder, ankle, and other joints, IKDC functional scores improve by approximately 30 points from baseline — consistently exceeding the 16.7-point Minimal Clinically Important Difference threshold that defines a meaningful patient-reported gain. Jerosch et al.'s prospective post-market clinical follow-up (PMCF) study found a mean improvement of 32.4 points sustained at three years, with patients reaching a mean final IKDC score of 80. Structural MRI supports those functional gains: MOCART scores of 81.6 to 84.3 at one year indicate greater than 80% defect filling and good integration between repair tissue and surrounding native cartilage, with earlier time points documenting the progressive maturation that tracks the biological timeline described in the previous section.

For the hip specifically, the evidence base is smaller. Perez-Carro et al. (2021) is the primary published reference; it reports functional benefit in focal hip cartilage lesions treated with the collagen scaffold and is cited in both the manufacturer's Clinical Evaluation Report and independent literature. That study has not yet been independently replicated for the hip, and no randomised controlled trial data currently exist for this application. Patients and clinicians weighing the option should be aware that hip-specific evidence, while present, does not yet match the volume accumulated for the knee.

More than 20,000 implantations across knee, hip, shoulder, ankle, thumb, and wrist over ten years of clinical use provide useful scale-of-use context — but implantation volume is not a substitute for joint-specific trial data, and it is worth holding that distinction clearly when reviewing the options.

How ChondroFiller compares to other injection options for the hip

The options available for hip cartilage injections differ not just in product but in what they are biologically designed to do — and that distinction matters when deciding which to discuss with a specialist.

Hyaluronic acid (viscosupplementation) acts as a lubricant. It can ease discomfort in the short term but is cleared by the joint within weeks and does not repair damaged cartilage structure. It belongs to symptom management rather than tissue restoration.

Corticosteroid has a legitimate, time-limited role: controlling acute inflammatory flare or reducing synovitis before another intervention. For ongoing cartilage loss it is not a structural solution, and repeated use has been associated with further cartilage volume reduction in published research.

Arthrosamid (polyacrylamide hydrogel / PAAG) is a permanent, non-biodegradable gel licensed for knee osteoarthritis. It cushions rather than regenerates — the hydrogel does not recruit cells, does not remodel, and is not replaced by repair tissue. Where it appears alongside ChondroFiller in a combination protocol, the two products are serving entirely different roles: Arthrosamid as a mechanical cushion, ChondroFiller as the biodegradable regenerative scaffold that supports the body's own repair processes.

Surgical alternatives — such as osteochondral grafting or arthroscopic implantation — remain an option for larger or more complex defects that exceed what an injectable scaffold can address. Surgery is a separate pathway requiring theatre conditions, not a variant of the outpatient injection service.

Search MSK lists specialists across the UK who offer injectable cartilage treatments — filter by region and specialty to find a consultant able to assess which option fits your hip and your circumstances.

Finding a specialist and preparing for your assessment

Most patients arriving at a specialist assessment already have some imaging — but a recent MRI of the hip, ideally within the past 12 months, is the single most useful thing to bring. Without it, the specialist cannot confirm defect morphology, gauge the viability of the surrounding cartilage, or determine whether the injectable scaffold route suits your particular lesion. If you have not had a hip MRI, your GP can arrange a referral, or the specialist's team can organise one ahead of the consultation.

Three questions are worth raising directly:

• Is the size and location of my defect suited to an injectable collagen scaffold, or does a different pathway fit my presentation better?
• What loading restrictions should I expect, and over what timescale?
• Is a combination protocol being considered — and if so, which components and why?

Bringing your scan, a brief note of your symptom history, and these questions will allow the consultation to move straight into clinical detail rather than background gathering — and in a pathway where defect morphology drives everything, the more recent and complete the imaging, the more productive that first conversation tends to be.

Search MSK lists specialists across the UK who offer ChondroFiller injection — filter by region and specialty to find one whose practice matches your hip and your circumstances.