The gap between pain relief injections and surgery

For many patients with thumb basal joint arthritis, the standard conversation runs along familiar lines: a corticosteroid injection to quieten the pain, then — when that stops working — a discussion about surgery. What often goes unasked is whether anything sits meaningfully between the two.

Corticosteroid injections have a legitimate role in managing acute flares, but their effect on pain averages around three to four months and they do nothing to address the underlying cartilage deficit. Hyaluronic acid offers lubrication to the joint surface; again, it is a symptom-management tool, not a repair one. Neither option alters the structural course of the condition.

At the other end of the scale, trapeziectomy — the UK gold standard for advanced carpometacarpal (CMC) osteoarthritis — involves removing the trapezium bone entirely. It is genuinely effective for end-stage disease, but it is permanently subtractive and irreversible, with a meaningful recovery period. For that reason, it is appropriately reserved for cases where conservative options have been exhausted.

Between these two tiers sits a well-recognised group of patients: those with confirmed CMC osteoarthritis whose symptoms are limiting daily function — opening jars, writing, gripping a steering wheel — but for whom surgery is not yet wanted or clinically indicated. ChondroFiller injection is designed for this group. Delivered as a single ultrasound-guided outpatient procedure, it works as an additive, structure-preserving scaffold that supports the joint's own repair processes rather than removing or replacing anything.

What happens to the basal joint in CMC arthritis

The thumb's basal joint — the carpometacarpal (CMC) joint — sits where the base of the thumb meets the trapezium, a small bone at the wrist. Its saddle shape allows the sweeping range of motion needed for grip and opposition, but that mobility comes at a cost: the CMC joint absorbs some of the highest contact forces of any small joint in the hand, concentrated by everyday actions such as pinching, twisting, and gripping.

When the cartilage lining this joint begins to thin and break down, the effects are predictable. Pain on loading, weakening of grip and pinch strength, and growing difficulty with tasks that once felt effortless — unscrewing a lid, writing, turning a key — are the characteristic pattern. Left unaddressed, that pattern tends to progress.

Clinicians classify disease severity using the Eaton-Littler grading system, a four-stage scale based on imaging. Grades 1 and 2 indicate early-to-moderate wear with cartilage still present; grades 3 and 4 reflect more advanced changes involving the subchondral bone beneath. The distinction matters because the more articular surface that remains, the more there is to work with — and the stronger the case for an approach that preserves rather than removes it.

How ChondroFiller injection works at the CMC joint

ChondroFiller is not a drug or a conventional injection fluid — it is a CE-marked Class III medical device: an acellular hydrogel composed of murine-derived Type I collagen, the same structural protein that forms the framework of native cartilage.

At the London Cartilage Clinic on Harley Street, it is administered as an outpatient procedure under ultrasound guidance, with no general anaesthetic or theatre time required. The product enters the joint in liquid form and gels in situ, conforming to the contours of whatever articular surface remains. That in-situ gelling is what allows the scaffold to coat the joint comprehensively in a single visit — the material adapts to the available space rather than requiring a precisely fitted implant.

The biological process is described as acellular matrix-induced chondrogenesis. Once the collagen scaffold is in place, it acts as both a structural support and a chemotactic signal, attracting the body's own progenitor cells — drawn from the synovium and subchondral bone — to migrate into the matrix and initiate endogenous repair. No donor cells are introduced at any stage.

The approach is explicitly additive. Rather than debriding or removing tissue, the scaffold works with what remains, covering and supporting the existing articular surface. The patient's own biology does the repair work; ChondroFiller provides the environment for that process to take hold. This injectable collagen scaffold pathway is what London Cartilage Clinic presents to patients under the Liquid Cartilage™ name.

What the clinical evidence shows for the thumb CMC joint

The most direct evidence for ChondroFiller injection at the thumb CMC joint comes from a 2025 prospective study by Corain et al. (PMC12213533), which enrolled 64 patients spanning the full Eaton-Littler spectrum — the largest published dataset for this application to date. A single ultrasound-guided intra-articular injection produced statistically significant improvements (P<0.001) across every measured outcome: NRS pain score, Jamar grip strength, pinch strength, and DASH functional disability score. Those gains held over more than two years of follow-up, which remains the longest published follow-up period for ChondroFiller specifically at this joint.

The results were not identical across disease stages, and the pattern is informative. Early-stage patients (Eaton-Littler grades 1 and 2) showed proportionally stronger gains in grip and pinch strength, suggesting that joints with more articular surface remaining may respond most robustly on mechanical measures. Advanced-stage patients (grades 3 and 4) showed proportionally greater improvement in DASH functional scores, indicating meaningful recovery even where disease had progressed further. Neither subgroup experienced adverse events of any kind across the two-year observation period. The most substantial changes occurred between 2 and 6 months post-injection, before plateauing at levels that remained significantly better than baseline.

What the evidence does not yet establish

The Corain study is a single prospective cohort — not a randomised controlled trial — and no head-to-head data yet compare ChondroFiller against corticosteroid, hyaluronic acid, or PRP at this joint. The broader context is consistent: a 2023 systematic review by Hasiba-Pappas et al. (PMC10573355) found that across all regenerative modalities for basal thumb arthritis — including PRP and lipofilling — high-quality long-term evidence is scarce and no large RCTs have been published for any of them. ChondroFiller's CMC-specific evidence is the most detailed available for a scaffold-based approach at this joint; it is also, for now, confined to one study. The optimal interval for re-injection has not been established in published literature. These are honest limitations that reflect where a maturing field currently stands — not reasons to discount findings that are, on their own terms, both statistically robust and clinically durable.

Who is suitable — and when to consider a combination approach

Candidates span a wider range than might be expected. The Corain 2025 study enrolled patients across all four Eaton-Littler grades, and the injection carries no upper age limit and no defect-size restriction — the in-situ gelling mechanism allows the scaffold to coat the entire articular surface in a single delivery. Active patients in their 60s and 70s who want to preserve their own joint while deferring surgery are among the most typical presenting cases at the London Cartilage Clinic.

The common thread among suitable candidates is confirmed CMC osteoarthritis with symptoms meaningfully limiting daily function — pain on gripping, reduced pinch strength, difficulty with routine tasks — alongside a preference not to proceed to trapeziectomy at this stage.

One prerequisite applies regardless of disease grade: joint mechanics must be stable. Significant ligament laxity or malalignment needs to be assessed and, where necessary, addressed before a ChondroFiller injection is appropriate.

Where cartilage loss is diffuse and end-stage (the equivalent of KL Grade IV), ChondroFiller injection alone may not be sufficient. Combination protocols are available at specialist centres, pairing ChondroFiller — the regenerative scaffold component — with Arthrosamid, a polyacrylamide hydrogel used for joint-space stabilisation. These are distinct products working through entirely different mechanisms; they should not be understood as interchangeable or as variants of a single treatment category. Patients who have previously undergone trapeziectomy at the thumb CMC joint are not candidates for ChondroFiller at that joint.

Getting assessed at London Cartilage Clinic

For patients who have moved past corticosteroid injections and are not yet ready for surgery, the practical next step is a clinical assessment at London Cartilage Clinic on Harley Street — the UK's certified delivery centre for the ChondroFiller injection pathway.

The assessment draws on imaging review and joint staging to confirm whether ChondroFiller injection is the right approach, or whether a combination protocol is more appropriate for the degree of cartilage loss present. Not every patient who enquires will be a straightforward candidate, and identifying that at assessment — rather than proceeding regardless — is part of what specialist evaluation is for.

The injection itself is an outpatient procedure under ultrasound guidance: no theatre, no general anaesthetic, no hospital admission. Professor Paul Y. F. Lee leads Liquid Cartilage™ delivery in the UK and performs the procedure image-guided; precise placement into the CMC joint space is a material part of how well the scaffold integrates. Most patients can expect to have a meaningful indication of their response within the first few months post-injection, before the benefits consolidate.

To arrange an initial assessment, visit londoncartilage.com.