Joint wear — especially in the knee, but also the hip, ankle, and smaller joints — is a common problem that can cause persistent pain and stiffness. Cartilage has a poor capacity to heal on its own, so patients often reach a point where they are weighing up options: physiotherapy and symptom management on one side, more involved interventional approaches on the other. This article explains what the ChondroFiller injection is, what the evidence currently suggests it can do, and how it differs from the surgical Liquid Cartilage procedure that is available when a non-surgical approach is not sufficient.

Why Cartilage Is Hard to Repair

Articular cartilage lines the ends of bones within joints, providing a smooth, cushioned surface that allows movement. It lacks a direct blood supply, which means that once worn or damaged it cannot regenerate through the normal wound-healing process. This is why even modest cartilage loss tends to be progressive and symptomatic over time, and why treatment options that offer biological support — rather than simply masking pain — are of clinical interest.

What Is ChondroFiller?

ChondroFiller is a CE-marked Class III medical device manufactured by Meidrix Biomedicals in Germany. It is a type I collagen hydrogel scaffold — a cell-free, collagen-based gel delivered in a sterile double-chamber syringe. When the two components are mixed during application, the resulting liquid solution flows into the cartilage defect and self-gels within three to five minutes at body temperature, forming a stable, biocompatible scaffold within the defect.

The scaffold works by attracting the patient's own progenitor cells from the surrounding synovium and subchondral bone marrow. These cells migrate into the matrix, differentiate into cartilage-producing chondrocytes, and begin synthesising new extracellular matrix — including type II collagen, the primary structural protein of healthy hyaline cartilage. Over an expected period of one to two years, the original collagen scaffold is gradually resorbed and replaced by patient-derived tissue. The device is intentionally cell-free: no cells are harvested, processed, or introduced from an external source.

The CE Class III marking, the manufacturer's clinical evaluation data, and the published safety and outcomes evidence all belong to ChondroFiller as a device.

The ChondroFiller Injection: A Non-Surgical Delivery Pathway

For accessible joints and smaller focal defects, ChondroFiller can be delivered as a non-surgical, ultrasound-guided outpatient injection. There is no theatre booking, no incision, no general anaesthetic, and no surgical recovery period. The procedure is carried out under ultrasound guidance to position the scaffold accurately within the defect, and the patient typically leaves on the same day.

This injection pathway suits patients with accessible lesions in joints such as the knee, ankle, thumb (trapeziometacarpal joint), or small hand joints, where a non-surgical approach is both technically feasible and clinically appropriate. It is best understood as a supportive, joint-preserving injection — not a cure, and not a reversal of established arthritis. Benefits vary between individuals.

What the Evidence Suggests

Clinical evidence from multiple investigations demonstrates meaningful improvements in patient-reported outcomes. In the knee, International Knee Documentation Committee (IKDC) scores have consistently improved by approximately 30 points over 12 to 36 months of follow-up. In the hip, modified Harris Hip Scores (mHHS) have improved by more than 30 points. MRI assessment using MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) scores — which evaluate the quality and integration of repair tissue — have ranged around 80 and above in published series, indicating high-quality defect fill. Independent work with the trapeziometacarpal joint has shown significant pain reduction and improved function.

The device has an exceptionally strong safety record. Across more than 19,000 units sold since 2013, no serious adverse incidents have been reported, and the overall complaint rate is under 0.1 per cent.

Weizel et al. (2020), published in Acta Biomaterialia, examined the mechanical behaviour of hydrogels for cartilage repair and provides relevant biomechanical context for the scaffold's properties. Clinical outcomes data for the trapeziometacarpal joint were reported by Corain et al. (2023) in Cartilage.

How ChondroFiller Compares with Stem Cell Approaches

Some patients ask how the ChondroFiller injection compares with stem cell therapy. Stem cell approaches — such as bone-marrow concentrate (BMAC) or micro-fragmented adipose tissue (mFAT) — involve harvesting, processing, and reintroducing the patient's own cells, making them a more involved, multi-step procedure. The ChondroFiller injection does not introduce cells: it relies entirely on the patient's endogenous progenitor cell recruitment once the scaffold is in place. The right choice depends on the individual's defect size, joint, activity demands, and clinical assessment.

When Surgery Is Needed: The Liquid Cartilage Protocol

The ChondroFiller injection is not suitable for every presentation. Larger defects, load-bearing joints with complex lesion geometry, or cases where biological augmentation is required may call for a surgical approach. In these situations, the appropriate pathway is the Liquid Cartilage procedure — a keyhole (arthroscopic), minimally invasive surgical protocol, not an injection.

Liquid Cartilage is Professor Paul Y. F. Lee's surgical technique, performed under anaesthesia in theatre. It delivers the ChondroFiller scaffold arthroscopically, combined with biological adjuncts such as platelet-rich fibrin, platelet-rich plasma, or tranexamic acid, and — where clinically indicated — the patient's own mesenchymal stem cells sourced from bone-marrow concentrate or micro-fragmented fat. This combination of scaffold, biologics, and optional MSC augmentation is what distinguishes the Liquid Cartilage protocol from a straightforward injection. A structured rehabilitation programme follows, typically with protected weight-bearing for the first six weeks.

In summary: ChondroFiller is the material (a CE-marked collagen scaffold); the ChondroFiller injection is a non-surgical outpatient procedure; and Liquid Cartilage is LCC's keyhole surgical protocol that uses the same scaffold plus biological adjuncts and, where indicated, stem cells. They are not the same thing, and the clinical pathway offered depends on the individual assessment.

In Summary

ChondroFiller is a non-surgical, injectable collagen gel with a favourable evidence base and a strong safety record for supporting worn or focally damaged joints without introducing cells. For patients with accessible lesions who are not yet candidates for surgery — or who wish to avoid surgery — the ChondroFiller injection offers a biologically active, outpatient option with realistic expectations. Where a surgical approach is warranted, the Liquid Cartilage protocol provides a more comprehensive pathway. The right choice is individual and requires a proper specialist assessment.

The London Cartilage Clinic offers assessment for both pathways. A consultation can help determine which approach — non-surgical injection, surgical Liquid Cartilage procedure, or a different option entirely — best suits your joint, defect, and circumstances.

References

Weizel, A., Distler, T., Schneidereit, D., & Friedrich, O. (2020). Complex mechanical behavior of human articular cartilage and hydrogels for cartilage repair. Acta Biomaterialia.

Corain, M., Zanotti, F., Giardini, M., Gasperotti, L., Invernizzi, E., Biasi, V., & Lavagnolo, U. (2023). The use of an acellular collagen matrix ChondroFiller Liquid for trapeziometacarpal osteoarthritis. Cartilage.