Introduction: Three distinct approaches, not two

When joint cartilage is damaged, patients searching for regenerative options frequently encounter three names: ChondroFiller, stem cell therapy, and Liquid Cartilage. Understanding what each actually is — and how they relate — matters before any consultation, because the right choice depends on defect size, joint location, and individual circumstances.

In brief: ChondroFiller is a CE-marked collagen scaffold (the material). It can be delivered non-surgically as an outpatient injection for accessible lesions, or it can be placed surgically as the centrepiece of LCC's keyhole procedure. That surgical procedure is called Liquid Cartilage — Professor Paul Y. F. Lee's protocol — which combines the ChondroFiller scaffold with biological adjuncts and, where appropriate, the patient's own mesenchymal stem cells (MSCs). Standalone stem cell therapy is a separate category: multi-stage cell harvesting and reintroduction without a scaffold-based regenerative framework of this kind.

What is ChondroFiller?

ChondroFiller is a type I collagen hydrogel scaffold, manufactured by Meidrix Biomedicals in Germany and regulated as a Class III CE-marked medical device. It is acellular — meaning it contains no cells itself. Once applied to a prepared cartilage defect it self-gels in approximately three to five minutes, forming a porous three-dimensional matrix that provides physical support and a chemotactic environment. The patient's own progenitor cells migrate into this scaffold and, over months, differentiate and lay down new cartilage-like tissue. The scaffold is gradually resorbed over one to two years as the native tissue matures.

The CE marking and published clinical evidence — including improvements in IKDC scores in the knee and modified Harris Hip Scores in the hip across manufacturer-sponsored and independent studies — belong to ChondroFiller as a device. This distinction matters when comparing it to stem cell preparations, which carry their own separate evidence bases.

The ChondroFiller injection: the non-surgical pathway

For suitable patients — those with accessible lesions, smaller defects, or joints where a full keyhole procedure is not warranted — ChondroFiller can be delivered as an ultrasound-guided outpatient injection. There is no theatre, no general anaesthetic, and no incision. The collagen gel is placed into the defect under imaging guidance and allowed to set. Recovery is quicker and the procedure is less involved than surgery.

This non-surgical route works best where the anatomy allows precise placement without arthroscopic preparation of the defect bed. It is not appropriate for all lesions; defect preparation, achieving a dry field for gelation, and ensuring stable scaffold anchorage are all factors that may favour the surgical route for larger or more complex defects.

The Liquid Cartilage procedure: ChondroFiller plus MSCs in keyhole surgery

Liquid Cartilage is not a product or an injection. It is the Lee Liquid Cartilage Protocol (LLC Protocol) — Professor Lee's keyhole surgical technique that uses ChondroFiller as its principal scaffold but combines it with a structured set of biological adjuncts and, where clinically indicated, mesenchymal stem cells from the patient's own bone-marrow aspirate concentrate (BMAC) or micro-fragmented adipose tissue (mFAT).

The procedure is performed arthroscopically under anaesthetic in theatre. Key steps include arthroscopic debridement and preparation of a stable defect rim, creation of a dry operative field using CO2 insufflation, application of a platelet-rich fibrin (PRF) primer to the defect bed, optional addition of fresh autologous MSCs where signalling support is most needed, injection and gelation of the ChondroFiller scaffold, and a post-gelation flood of platelet-rich plasma (PRP) with tranexamic acid. Peri-operative optimisation, compression, early neuromuscular activation, and a structured rehabilitation programme complete the protocol.

Liquid Cartilage is therefore a designed surgical system — aligning the physics of scaffold anchorage, the chemistry of gelation and fibrin stabilisation, and the biology of platelet and stem-cell signalling. It is suited to larger or load-bearing defects in joints such as the knee, hip, shoulder, and ankle, where achieving the ideal regenerative environment requires direct surgical access.

Standalone stem cell therapy: a separate category

Standalone MSC-based treatments — where cells are harvested from bone marrow or adipose tissue, potentially processed or expanded, and then reintroduced into the joint — represent a different approach. They are not combined with a resorbable scaffold in the ChondroFiller/Liquid Cartilage sense. Published literature reports that intra-articular MSC injections can reduce pain and may provide some support for cartilage biology, particularly in early-stage osteoarthritis, though outcomes vary and the evidence base is still developing relative to scaffold-based techniques.

The multi-stage nature of many MSC protocols — extraction, processing or lab preparation, and subsequent reinjection — makes them more involved than a ChondroFiller injection. Within the Liquid Cartilage framework, MSCs are used differently: as a biological adjunct added to a prepared defect at the time of surgery, acting synergistically with PRF, PRP, and the scaffold rather than as a standalone cellular treatment. Conflating these is a common source of confusion.

Comparing the three approaches

A useful way to think about the choice is by matching complexity to need.

• ChondroFiller injection (non-surgical): Single outpatient appointment; no theatre; ultrasound-guided; suitable for accessible defects in smaller or less mechanically demanding joints; quicker recovery; CE-marked device with published outcome data.
• Liquid Cartilage — LLC Protocol (keyhole surgery): Theatre-based arthroscopic procedure under anaesthetic; delivers ChondroFiller scaffold with PRF, PRP, TXA, and optional autologous MSCs; suited to larger or load-bearing defects; structured rehabilitation over weeks to months; performed by Professor Lee and specialist-trained surgeons.
• Standalone stem cell therapy: Multi-stage; cells harvested and reintroduced without a scaffold-based regenerative framework; may suit certain osteoarthritic presentations; outcomes variable; evidence base continues to evolve.

None of these is a cure for osteoarthritis, and none can guarantee cartilage regrowth. Clinical evidence suggests meaningful functional improvement in appropriately selected patients for both ChondroFiller and MSC-based approaches, but individual results vary. The right choice depends on the joint, the defect, the stage of wear, and the patient's goals and fitness for surgery.

How to decide

The starting point is always assessment rather than assumption. A patient with a focal defect in a smaller joint may be well served by the ChondroFiller injection without surgery. A patient with a larger or load-bearing defect where thorough defect preparation and scaffold anchorage are critical is more likely to be directed towards the Liquid Cartilage procedure. A patient whose primary issue is widespread early arthritis rather than a focal defect may be offered a different biological support strategy altogether, which might or might not include MSCs.

Understanding which pathway applies requires imaging, a detailed joint assessment, and an honest conversation about what the evidence does and does not support in each case.

Assessment at London Cartilage Clinic

London Cartilage Clinic, based on Harley Street and part of the MSK Doctors group, offers assessment for the full range of cartilage-preserving options. Professor Paul Y. F. Lee, who developed the Lee Liquid Cartilage Protocol, provides individual evaluation to determine whether the ChondroFiller injection, the Liquid Cartilage surgical procedure, or another approach — including biological support strategies — is most appropriate for a given patient's joint and goals. Expectations are kept realistic throughout.

References

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.