Joint cartilage has very limited capacity to heal itself, and worn or damaged cartilage can cause pain and reduced function that persists despite physiotherapy and simple pain relief. This article compares ChondroFiller — a non-surgical collagen scaffold injection — and the Liquid Cartilage surgical protocol — a keyhole procedure using the same scaffold combined with biological adjuncts — with the traditional surgical and non-surgical options that patients are most likely to encounter. The goal is to help you understand what each approach can and cannot achieve before you speak with a specialist.

Traditional Treatments

Microfracture is the most commonly performed first-line surgical procedure for focal cartilage defects. The surgeon makes small perforations in the underlying bone to allow bone-marrow cells to migrate into the defect and form a repair tissue. The limitation is that this repair tissue is predominantly fibrocartilage, which is biomechanically inferior to native hyaline cartilage and tends to degrade over time, with clinical benefit often declining after two to five years and high reoperation rates reported in the literature.

Autologous chondrocyte implantation (ACI) and its matrix-assisted variant (MACI) are two-stage cell-based procedures. At the first operation a biopsy of healthy cartilage is taken; the cells are cultured in a laboratory over several weeks and then re-implanted at a second operation, either sutured under a membrane or seeded onto a scaffold. ACI and MACI can achieve hyaline-like repair tissue and produce meaningful functional improvement — published data show improvements in IKDC scores of approximately 30 to 35 points — but the two-stage process, significant surgical complexity, donor-site considerations, risks of graft hypertrophy, and extended rehabilitation make them demanding for patients and services alike.

Osteochondral autograft transplantation (mosaicplasty) transfers cylindrical plugs of bone and cartilage from a low-load area of the patient's own joint to fill a defect. It is a single-stage procedure suitable for smaller lesions but carries donor-site morbidity, and results tend to deteriorate for defects larger than about 2.5 cm².

Hyaluronic acid injections work primarily by lubricating the joint and may offer short-term relief of symptoms, but they do not address underlying cartilage damage and are not a disease-modifying or restorative option.

The ChondroFiller Injection

ChondroFiller is a Class III CE-marked type I collagen hydrogel scaffold, manufactured by Meidrix Biomedicals in Germany. It is cell-free: no donor cells, no laboratory culture stage, and no genetic modification. When delivered into a joint it self-gels within approximately three to five minutes, forming a scaffold that recruits the patient's own progenitor cells to support cartilage regeneration.

As a non-surgical pathway, the ChondroFiller injection is administered as a single outpatient procedure under ultrasound guidance — no theatre, no incision, and no general anaesthetic. It is suited to accessible lesions and smaller joints, and patients typically notice gradual improvement in comfort and movement over the following weeks. Because it is an injection rather than an operation, recovery is usually straightforward.

Published comparative data position the ChondroFiller scaffold alongside ACI and MACI in terms of IKDC functional improvement (approximately 30 points over 12 to 36 months) while requiring none of the multi-stage surgical burden. Its safety profile is notably favourable: complications are rare and reoperation rates in published series range from approximately 3 to 8 per cent, compared with rates of up to 37 per cent for ACI and up to 41 per cent for microfracture. A 2023 study of acellular collagen matrix injection for thumb-base osteoarthritis reported improvements in pain and grip strength (Corain et al., 2023, Cartilage), though responses vary between people and joints and benefits cannot be guaranteed.

ChondroFiller is best understood as a biologically supportive joint-preservation measure, not a cure or reversal of arthritis. The CE marking, the device evidence, and the published clinical outcomes data all belong to ChondroFiller as a device.

The Liquid Cartilage Surgical Protocol

For larger or load-bearing defects, or where a non-surgical pathway is not appropriate, there is a distinct surgical option available at the London Cartilage Clinic: the Lee Liquid Cartilage Protocol (the Liquid Cartilage procedure). This is not the same as the ChondroFiller injection.

Liquid Cartilage is a keyhole (arthroscopic) surgical protocol developed by Professor Paul Y. F. Lee. It delivers the ChondroFiller scaffold arthroscopically during surgery, combined with biological adjuncts — typically platelet-rich fibrin or platelet-rich plasma and tranexamic acid — and, where clinically indicated, the patient's own mesenchymal stem cells harvested from bone-marrow concentrate (BMAC) or micro-fragmented adipose tissue (mFAT). The procedure includes peri-operative optimisation and a structured rehabilitation programme.

Because Liquid Cartilage is genuine keyhole surgery, it involves theatre, anaesthetic, and a structured recovery. It is used for larger or more complex defects in weight-bearing joints such as the knee, hip, shoulder, and ankle, where the non-surgical injection pathway may not be sufficient. The combination of the scaffold with cellular and biological adjuncts is designed to support regeneration of more durable tissue in challenging defects.

Liquid Cartilage is not an injection. Its CE marking and device evidence belong to the ChondroFiller scaffold it uses; the protocol itself is Professor Lee's surgical technique.

How the Options Compare

Choosing between these approaches depends on the joint involved, the size and depth of the defect, the patient's age and activity level, and their preference for surgical versus non-surgical management. A broad summary of how they differ:

• Hyaluronic acid: non-surgical injection; symptomatic lubrication only; no structural repair.
• Microfracture: single-stage keyhole surgery; forms fibrocartilage (inferior durability); high long-term reoperation rates.
• ACI / MACI: two-stage cell-based surgery; hyaline-like tissue; high complexity, cost, and rehabilitation burden.
• Mosaicplasty: single-stage; hyaline tissue transfer; donor-site morbidity; limited to smaller defects.
• ChondroFiller injection: non-surgical, outpatient, ultrasound-guided; hyaline-like repair potential; favourable safety profile; suited to accessible lesions.
• Liquid Cartilage: keyhole surgical protocol; ChondroFiller scaffold plus biologics and optional MSC; for larger or load-bearing defects; theatre and structured recovery required.

None of these options is suitable for every patient. The degree of underlying arthritis, the presence of osteochondral bone involvement, joint alignment, and other factors all influence which approach — or combination of approaches — a specialist would recommend.

What the Evidence Shows

Evidence for the ChondroFiller scaffold's clinical performance comes from published studies across multiple joints. Comparative data show IKDC functional improvements of approximately 30 points over 12 to 36 months — broadly comparable to ACI and MACI — but achieved through a simpler, single-stage procedure. MRI-based tissue quality scoring (MOCART) in knee and hip studies has been reported around 80 and above at follow-up, suggesting structurally meaningful repair. Microfracture, by comparison, often shows declining IKDC scores beyond two to five years and higher rates of subsequent surgery.

For the Liquid Cartilage surgical protocol, the addition of biological adjuncts and mesenchymal stem cells is intended to support regeneration in more demanding defects where scaffold alone may be insufficient, but patients should be counselled that individual responses vary and that no cartilage regeneration procedure guarantees a specific outcome.

Conclusion

Patients researching cartilage treatment face a genuinely varied landscape: from symptomatic injections through single-stage surgical options to complex two-stage procedures. The ChondroFiller injection occupies a distinct non-surgical position — an outpatient collagen scaffold delivery that may suit patients with accessible lesions who wish to avoid an operation. The Liquid Cartilage protocol at the London Cartilage Clinic is the surgical counterpart for cases where keyhole intervention is indicated, deploying the same scaffold with biological support in theatre.

Neither approach is a cure for arthritis, and realistic expectations matter. At the London Cartilage Clinic, Professor Paul Lee can assess which pathway — surgical or non-surgical — is appropriate for your joint, defect, and circumstances.

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.