Two injections, two different jobs

The question is not which injection works better — it is which problem each injection is designed to solve.

ChondroFiller® is an injectable collagen scaffold placed into a focal, contained cartilage defect. It works by recruiting the patient's own repair cells into a structured matrix, a process called acellular matrix-induced chondrogenesis. The target is a discrete lesion: an area of damaged cartilage up to 6 cm², with the surrounding tissue still reasonably intact. Structural support is the goal.

Cingal takes a different approach entirely. It combines cross-linked hyaluronic acid with a corticosteroid (triamcinolone) to address the symptoms of diffuse knee osteoarthritis — pain, swelling, stiffness, and reduced motion. It is a palliative agent; it does not repair a cartilage defect.

The fork between them is defect morphology. A contained focal lesion (ICRS grade 2–4, up to 6 cm²) points toward ChondroFiller. Generalised cartilage thinning without a discrete, bounded defect points toward Cingal. Choosing between them on efficacy alone is like comparing two tools with no shared job.

How ChondroFiller works inside a focal defect

ChondroFiller® liquid is composed of murine-derived Type I collagen — the same structural protein found in native articular cartilage matrix — processed into an acellular, injectable form. Once placed inside the defect cavity, it transitions from liquid to gel in situ, creating a three-dimensional scaffold that fills the lesion contour precisely. Classified as a CE-marked Class III medical device, the product carries the regulatory designation that applies to implantable devices with the highest level of patient-body contact.

The biological process that follows is what distinguishes this approach from symptom management. Because the scaffold contains no donor cells of its own, it relies on the patient's progenitor cells — drawn from the surrounding synovium and the subchondral bone beneath the defect — migrating into the matrix and differentiating within it. The tissue that consolidates over the following months is hyaline-like in character, a clinically meaningful difference from the fibrocartilage produced by marrow-stimulation techniques such as microfracture, which is mechanically weaker and less durable over time.

At London Cartilage Clinic, delivery is via ultrasound-guided injection in an outpatient setting. The image-guided approach allows precise placement of the scaffold within the focal lesion without incisions or theatre admission. This single-stage pathway is the route by which ChondroFiller® reaches the defect; more than 19,000 cases have been completed globally across the knee, hip, ankle, and smaller joints, providing a substantial body of real-world procedural experience behind any individual assessment.

What Cingal offers — and where it stops

The dual-action mechanism behind Cingal is straightforward. Triamcinolone acetonide — the corticosteroid component — reduces intra-articular inflammation quickly, with many patients noticing pain relief within days. Cross-linked hyaluronic acid then sustains this window by restoring some of the viscoelastic properties that osteoarthritic synovial fluid loses over time, a lubrication effect that may persist for up to six to twelve months in suitable patients.

What neither component delivers is structural repair. Hyaluronic acid in this context acts as a viscosupplement — a lubricant and cushion — not as a scaffold or biological agent capable of stimulating tissue formation. Patients sometimes assume that easing joint pain implies that underlying cartilage is recovering; that inference does not apply here.

The corticosteroid element also carries a limitation relevant to longer-term planning. McAlindon et al. (JAMA 2017) found that repeated intra-articular triamcinolone injections over two years were associated with greater cartilage volume loss compared with placebo — a finding that argues against using Cingal as an ongoing maintenance strategy. At London Cartilage Clinic, it is positioned as a short-term palliative tool: appropriate when the primary clinical problem is diffuse OA-related pain and inflammation, and when there is no discrete, bounded lesion that a regenerative scaffold approach could address.

ChondroFiller clinical outcomes in the knee

Published knee data across four studies give a consistent picture: IKDC scores improve by approximately 30 points following ChondroFiller® treatment. To appreciate what that number means clinically, the established Minimal Clinically Important Difference for the IKDC — the threshold below which a patient is unlikely to perceive meaningful functional benefit — is 16.7 points. A 30-point gain is nearly double that threshold.

The longest available follow-up comes from the Jerosch et al. post-market clinical follow-up (PMCF) study, which recorded a mean improvement of 32.4 IKDC points sustained — and marginally increased — at three years, with participants reaching a functional score of 80. That trajectory matters: it suggests the repair process continues to consolidate rather than deteriorate once the scaffold has matured.

MRI findings corroborate the functional data. MOCART scores in European studies range from 81.6 to 84.3, indicating that more than 80% of the defect volume is filled and well-integrated with surrounding native cartilage at twelve months. Imaging at four weeks already shows early scaffold incorporation; the scores progress to their final range by one year, reflecting the gradual maturation of the repair matrix visible on sequential scans.

On safety, the complication rate is approximately zero and the reoperation rate falls between 3% and 8% — considerably lower than the benchmarks for ACI/MACI (reoperation up to 37%) and microfracture (up to 41%).

One important caveat: the available trials are largely manufacturer-sponsored, and independent long-term data beyond three years remain limited. No head-to-head randomised trial against Cingal exists — nor would one be straightforward to design, given that the two treatments address structurally different clinical problems.

When Cingal and ChondroFiller work in sequence

Not every patient arrives with a clean diagnosis at one end of the focal-versus-diffuse spectrum. Some knees show a background of early generalised osteoarthritis alongside a discrete, bounded lesion sitting within it — a pattern where both products may play a role, but at different moments and for different reasons.

In practice, this can look like the following: a patient with persistent OA-related pain receives Cingal to reduce inflammation and improve day-to-day comfort while baseline imaging is established. At annual MRI review, if a focal chondral defect is identified or shown to be progressing, the clinical question changes — from symptom management to whether structural intervention is now appropriate. At that point, ChondroFiller® can be introduced as an ultrasound-guided injectable scaffold to address the contained lesion directly, targeting repair rather than ongoing symptom suppression.

This is not a commercial ladder — it is MRI-driven clinical decision-making. Nor does it apply to everyone: patients with a clearly defined focal defect at first presentation may be suitable for ChondroFiller® from the outset, without a Cingal step preceding it. The two injections remain distinct by design and should not be collapsed into a single treatment category.

Getting the right assessment first

The decision between these two pathways ultimately rests on information that a clinical assessment provides — not on which treatment carries more impressive headline numbers.

What determines the recommendation is imaging: an MRI scan that can confirm whether a focal, contained defect is present, how large it is, and what condition the surrounding cartilage holds. Patients who arrive with recent, high-quality knee MRI already have the foundational data; those without are typically scanned before a pathway is proposed. Clinical examination adds what imaging cannot: symptom timeline, load-bearing history, activity goals, and the patient's own threshold for intervention.

The outcome of that assessment may be ChondroFiller®, Cingal, a phased plan combining both, or an alternative pathway altogether. The finding drives the recommendation, not the other way round — and that anatomy-led logic is what distinguishes a genuine joint-preservation consultation from a product-selection exercise.

For patients at this decision point, the London Cartilage Clinic on Harley Street offers that assessment; initial consultations can be arranged through londoncartilage.com.