The short answer

Liquid Cartilage™ may be considered when there is a defined, symptomatic cartilage defect being treated arthroscopically, rather than widespread wear across the joint. On this site it refers to ChondroFiller™, a cell-free type I collagen scaffold placed into the defect during keyhole surgery, where it sets into a hydrogel in about 3–5 minutes. That puts it in the cartilage-restoration part of the pathway, not in the same category as a clinic-room hyaluronic-acid injection; 2024 EUROVISCO guidance discusses hyaluronic acid as symptom management for knee osteoarthritis.

In practice, it is usually considered after simpler symptom-management measures have not been enough and where the joint is still reasonably preserved. Suitability depends on the defect pattern, joint mechanics and how much osteoarthritis is already present. The published results are encouraging but still based on smaller cohorts than some longer-established techniques: a 2024 knee series reported improved scores through 12 months in 17 patients, and a hip cohort reported good or excellent 3- to 5-year outcomes in 17 of 21 followed patients. By contrast, patients with pre-existing Tönnis 2–3 osteoarthritis did poorly in the hip study, so diffuse advanced osteoarthritis usually falls outside the main scope for focal cartilage repair.

An implant, not a knee gel injection

The key practical difference is where the treatment is put and what it is trying to do. In the 2024 EUROVISCO guidance, hyaluronic-acid viscosupplementation sits in the symptom-management lane for knee osteoarthritis: the material is injected into the joint space to try to ease pain and stiffness. ChondroFiller™ is different. It is not a viscosupplement or a routine clinic-room “knee gel” injection; it is placed during arthroscopy into a defined cartilage defect, so the aim is defect repair rather than general symptom relief across an arthritic joint.

That difference matters because it is usually not a straight choice between two versions of the same treatment. ChondroFiller™ is described as a cell-free type I collagen matrix that gels within the defect and acts as a scaffold for the body’s own repair response. Some of that wording, including the gelling description, comes partly from the manufacturer, but the broad picture is consistent with the published clinical literature describing an arthroscopically applied collagen implant for focal cartilage lesions. In simple terms, one approach is used to manage osteoarthritis symptoms inside the whole joint; the other is used to fill a localised area of cartilage loss during surgery.

Why it may hold up differently from microfracture

What matters most in this comparison is often not the first year, but what happens after that. In knee studies, microfracture can look acceptable at 12 to 24 months, particularly in younger patients with smaller femoral-condyle lesions, yet the improvement is not consistently sustained. A 2024 meta-analysis noted that microfracture results commonly start to fade after about 2 to 3 years, and a 2024 systematic review judged its long-term efficacy limited for medium-size to large defects. There is still no direct knee trial showing that ChondroFiller™ does better than microfracture, so this remains a cautious explanation rather than a definitive ranking.

The likely reason is mechanical as much as clinical. Microfracture works by stimulating marrow through small holes in the subchondral bone, and the repair tissue is often described as fibrocartilage-like tissue, which may be less resilient over time. ChondroFiller™, by contrast, is a single-stage collagen scaffold placed into the defect to support defect fill in a more structured matrix environment. That does not prove superior durability, but it helps explain why matrix-based repairs are often discussed as potentially more stable beyond the early period. In a 10-year randomised AMIC study, for example, matrix-augmented repair stayed stable after the first 2 years while the microfracture group deteriorated; direct ChondroFiller™ knee data are still much earlier, with a 2024 case series reporting follow-up only to 12 months.

What the ankle picture looks like

For ankle and talar cartilage defects, Liquid Cartilage™ may be a selective option rather than a settled default. A 2025 paper specifically on osteochondral lesions of the talus shows that direct ChondroFiller™ use in the ankle is already part of the clinical literature, but the published signal is still mainly case-series level rather than high-level comparative evidence. That matters because the ankle is not simply a smaller knee: in talar lesions, surgeons usually weigh the lesion’s size, whether it is contained, the condition of the bone beneath it, ankle stability and any previous surgery as much as the product name itself. Cross-joint use is part of the scaffold’s appeal, but the strength of evidence still varies by joint.

The broader talus literature gives some context without proving that ChondroFiller™ is superior. In a 2024 systematic review and meta-analysis of second-look arthroscopy, bone marrow stimulation showed lower cartilage-quality success than fixation, osteochondral transplantation and cartilage-implantation techniques. Likewise, a 9-patient ankle case series using an arthroscopic collagen-matrix approach reported improved AOFAS and pain scores at 12 months for lesions averaging 2.1 cm². The practical takeaway is that ankle use currently looks like a plausible option for selected focal talar lesions, especially where matrix-based repair is being considered, but not yet one with strong ChondroFiller™-specific comparative proof.

When it is less likely to help

A more guarded discussion is needed when pain is coming from diffuse osteoarthritis rather than one contained cartilage defect. In a 3- to 5-year hip cohort, ChondroFiller™ outcomes were poorer when pre-existing osteoarthritis was already present, which fits the wider principle that a focal scaffold is less likely to solve symptoms driven by broad joint wear.

The same caution applies in the knee, hip or ankle if the mechanics around the defect are unfavourable. Marked malalignment, ligament instability, meniscal deficiency or untreated bone pathology can keep overloading the repaired area, so some cases are considered for combined joint-preservation surgery, a different restorative technique, or, in more advanced disease, a replacement pathway rather than an isolated scaffold. Technique appears to matter as well: in a wrist follow-up arthroscopy study, overfilled defects developed fibrous tissue, whereas flush applications did not. Very large or deep defects may therefore be better served by another option than Liquid Cartilage™ alone.

How to decide in clinic

Clinic decisions usually come down to four questions: is this a focal defect or diffuse osteoarthritis; does it need arthroscopic repair rather than an injection; in the knee, is microfracture still sensible given 2024 evidence that results may fade after 2–3 years; and in the ankle or talus, is there bone involvement or instability that changes the plan. A 2025 talus paper shows direct ChondroFiller™ use is being reported, but the ankle evidence is still early.

Technique matters too. In a wrist follow-up study, overfilled defects developed fibrous tissue, suggesting that case selection and application influence results, not just the product. Overall, this route is mainly considered for a defined focal lesion, not pain driven by advanced, diffuse wear.

London assessment route

Those clinical questions come first. Liquid Cartilage™ is delivered in the UK at the London Cartilage Clinic on Harley Street; assessment can be booked via londoncartilage.com.

1. [1] Microfracture for full-thickness chondral lesions of the knee in elite athletes leads to high return-to-play rates. (2025). https://doi.org/10.1002/ksa.12808 https://doi.org/10.1002/ksa.12808