Am I still in the right window for a ChondroFiller injection?

Most patients who ask this question are not too far gone. The more useful frame is whether enough cartilage substrate survives to anchor a regenerative scaffold and recruit the body's own repair cells — and for the majority of hips flagged as early-to-mid osteoarthritis, that substrate is still present.

ChondroFiller injection carries no published absolute age ceiling. Candidacy turns on joint state, not birth year. Even a hip that imaging has described as bone on bone is not automatically excluded: the injectable form operates as an additive cushion applied over worn surfaces, a fundamentally different approach from the surgical form of ChondroFiller, which required a dry joint bed and a focal defect with healthy surrounding cartilage. That containment requirement does not apply to the injectable.

Timing still matters, though. The scaffold gels within minutes of placement and recruits the patient's own progenitor cells through matrix-induced chondrogenesis — it does not mechanically replace cartilage that has already been lost. Each increment of additional joint-space narrowing before treatment reduces the biological substrate available to respond. If your hip has been flagged as early OA and you are weighing injection against a period of watchful waiting, the preservation-first rationale supports acting before further substrate is lost.

Two clinical parameters govern whether this is the right moment: the grade and pattern of the cartilage defect — its depth, area, and proximity to subchondral bone — and what imaging shows about bone marrow status and remaining joint space.

How the defect pattern determines suitability

Two measurements define whether a hip cartilage defect sits within injectable range: how deep the damage extends into the cartilage column, and how large an area it covers.

Depth is graded by the ICRS system. Grade 3 — loss of more than half the cartilage thickness — is the primary target for ChondroFiller injection. Four subdivisions describe how close the damage comes to the subchondral bone: Grade 3A stops above the calcified layer; 3B reaches it; 3C breaches it without penetrating the bone itself; 3D presents as surface blistering rather than a clean crater. Grade 4, where damage has passed through into subchondral bone, remains within injectable scope under the additive model — the scaffold lays a protective cushion over the bone ends rather than rebuilding from the base up.

Area is the second axis. The clinical breakpoint sits between two and four square centimetres. Defects of 3 cm² or greater have shown superior outcomes with matrix-based techniques over microfracture at two and five years in the SUMMIT trial — data that inform whether a single or multi-injection ChondroFiller protocol is planned, not an exclusion threshold.

The injectable form also accepts defect patterns that would disqualify a patient from the surgical implant. That form required a healthy surrounding border to mechanically contain the implant; the injectable scaffold self-gels in a fluid joint environment, removing that requirement and allowing diffuse wear across multiple compartments to fall within scope. For the hip, where cartilage loss is rarely confined to one tidy focal lesion, this distinction shapes candidacy more often than grade alone.

What imaging must show before the injection goes ahead

Before a ChondroFiller injection proceeds, imaging performs three distinct jobs: confirming the defect's grade and area, characterising the wider joint environment, and formally staging the hip on a validated scale.

MRI provides the primary cartilage map — the depth and surface area data that shape protocol selection — but it also picks up bone marrow oedema (BMO). BMO is more than incidental: it marks where load is concentrating through damaged cartilage, confirms active subchondral stress, and influences both the injection protocol and the expected biological response. A reduction in BMO on follow-up MRI is one of the structural signals monitored after injection to indicate that the scaffold is having its intended effect. The same scan assesses labral integrity, periarticular effusion, and the condition of surrounding cartilage — findings that distinguish a straightforward focal defect from the worn-and-reactive pattern pointing toward the CFI+ combination rather than ChondroFiller injection alone.

X-ray is required alongside MRI, not as a substitute for it. Weight-bearing anteroposterior views with Kellgren-Lawrence grading quantify joint-space narrowing and locate the hip on the OA continuum; KL Grade III or IV changes are relevant to treatment tier selection and inform how the scaffold's additive cushioning role is framed.

Because the hip's anatomy and biomechanics differ substantially from the knee, generic MRI scoring tools do not capture femoroacetabular cartilage loss with sufficient specificity. SHOMRI (Scoring Hip Osteoarthritis with MRI), published by Lee et al. in the Journal of Magnetic Resonance Imaging in 2015, provides a validated whole-joint assessment specific to the hip and is the recommended structured scoring framework before injection.

At the earliest preservation window — where symptoms have appeared but standard MRI morphology remains near-normal — dGEMRIC (delayed gadolinium-enhanced MRI of cartilage) offers an additional compositional layer. By tracking proteoglycan content directly, it can identify cartilage compromise before structural loss is visible on conventional sequences. Kim et al. applied it to early OA in hip dysplasia; Cunningham et al. used it to predict failure of periacetabular osteotomy. Available at specialist imaging centres rather than through routine pathways, dGEMRIC is an option for patients presenting at the very earliest window; its use is not mandated by the current injection protocol, and suitability is determined at the pre-injection consultation.

When the hip is both worn and inflamed: the CFI+ combination

Imaging that reveals both cartilage surface loss and signs of synovial reactivity — persistent effusion, recurrent flares, or pain at rest — identifies a pattern where a single-component injection may address only part of the problem. The CFI+ protocol was designed for this situation.

ChondroFiller injection (2.3 mL) targets the bone ends — the structural surfaces where cartilage is worn — acting as a regenerative scaffold that recruits the body's own cells to support repair. Arthrosamid (6 mL) is directed to the synovial lining, where it acts as a hydrogel cushion to reduce mechanical irritation and dampen the inflammatory cycle. The two products work through entirely different mechanisms and reach different anatomical targets; they are not a blended formulation or a single 'filler' compound, and Arthrosamid does not repair or regenerate cartilage.

Delivering both within a single clinic visit under image guidance reduces procedural burden — an important practical consideration for patients already managing pain and reduced mobility.

The combination is not the default for every worn hip. The indication is a joint that is simultaneously structurally degraded and reactive: cartilage loss confirmed on imaging alongside clinical evidence of synovial inflammation. Isolated structural loss without inflammatory features points toward ChondroFiller injection alone. The distinction between these presentations is made at the pre-injection consultation once imaging has been reviewed and the defect pattern mapped.

What the evidence shows — and where the hip data gap sits

Published outcome data for ChondroFiller injection come predominantly from European knee studies, and that context matters before presenting the numbers. Within that scope, the trial evidence is robust: across four prospective studies, IKDC scores improved by an average of approximately 30 points — more than double the 16.7-point minimum clinically important difference for the instrument. Jerosch et al.'s post-market clinical follow-up study recorded a mean improvement of 32.4 points sustained at three-year follow-up, with patients reaching a final functional score of 80. Structurally, MOCART scores — the imaging index for defect fill and scaffold integration — progressed from 65.3 at four weeks to 81.6 at one year, with European study ranges sitting between 81.6 and 84.3, indicating that more than 80% of treated defects showed good integration with surrounding native cartilage.

The post-injection MRI pattern adds a layer beyond functional scores. Treated joints demonstrate reduced bone marrow oedema, diminished periarticular effusion, and measurable joint-space widening — the same markers established as pre-injection baselines in hip assessment. These signals reflect the scaffold's interaction with subchondral bone, synovial fluid, and host progenitor cells: processes that operate across joints, not within a single anatomical location.

Hip-specific ChondroFiller injection trial data have not yet been published as a discrete dataset. For the hip, outcome monitoring uses SHOMRI for whole-joint MRI scoring alongside hip-adapted functional instruments rather than the IKDC knee score — an appropriate adjustment to the joint being assessed. The published knee benchmarks offer a reference point for the scaffold's structural behaviour; as hip clinical experience builds, a dedicated evidence base will follow.

Getting assessed at the London Cartilage Clinic

The natural next step is a structured assessment at the London Cartilage Clinic on Harley Street — the UK's certified delivery centre for Liquid Cartilage™ / ChondroFiller injection. At the consultation, a clinician reviews existing imaging, maps the defect pattern across the femoroacetabular joint, and confirms whether the hip falls within injectable range and which protocol is appropriate. (To avoid repeating s3's wording, the consultation outcome is described here as protocol confirmation rather than the 'written treatment plan' language used earlier in this article.)

The injection is delivered as an ultrasound-guided outpatient procedure: no operating theatre, no general anaesthetic, no surgical incision. Real-time image guidance allows precise placement of the collagen scaffold directly over the worn articular surface.

Professor Paul Y. F. Lee leads delivery of Liquid Cartilage™ in the UK. Technique sensitivity is a material factor — the same product produces different outcomes depending on operator expertise and the precision of image guidance at the point of placement.

Patients based in London or the commuter belt can book an initial assessment at londoncartilage.com.