The short answer on candidacy

Most adults with hip cartilage damage — whether a single focal lesion or more widespread wear — are worth a formal assessment for ChondroFiller hip injection, provided the joint is mechanically stable. The treatment spans two broad candidacy tracks, and understanding which applies is the first practical step.

The first track covers isolated, focal cartilage damage: a discrete Grade III or IV defect with healthy surrounding cartilage borders. This is the profile most commonly seen in younger or physically active patients with femoroacetabular impingement (FAI) or a post-traumatic chondral injury. The second track is deliberately broader — diffuse cartilage wear extending up to Kellgren-Lawrence Grade IV osteoarthritis, where the collagen scaffold can coat larger areas of the articular surface in a single in-clinic appointment. There is no upper age limit on the injection pathway, and active patients in their 60s and 70s are well within its intended scope.

The most reliable poor-fit signals are mechanical rather than age-related. Untreated ligament laxity, significant joint malalignment, or a meniscal deficit that is actively driving cartilage loss would continue to stress any newly supported tissue — making those issues a prerequisite to address before, or alongside, any cartilage-directed treatment. Advanced degenerative change alone does not exclude the injection form; it is mechanically unsupported joints, not age or disease severity, that most consistently predict a poor outcome.

What ChondroFiller is and how it works in the hip

ChondroFiller is a CE-marked Class III medical device — an acellular Type I collagen scaffold that gels in situ once placed inside the joint. No donor or laboratory-grown cells are introduced. Instead, the material acts as a chemotactic matrix, drawing the patient's own progenitor cells from the surrounding synovium and subchondral bone into the scaffold, where they can mature and support the body's own repair processes. This mechanism is known as acellular matrix-induced chondrogenesis.

In the current service pathway, ChondroFiller is delivered as an ultrasound-guided outpatient injection — a standard 2.3 mL dose placed into the joint in a fluid environment. There is no theatre admission, no general anaesthetic, and no surgical incision.

The biology has a practical implication for who benefits most. A collagen scaffold can only recruit and support cells effectively when the surrounding cartilage retains some viable tissue and the joint is not being subjected to abnormal mechanical loading. Severely degraded tissue or a joint under persistent abnormal stress provides a poor environment for that cellular recruitment — which is why the condition of the cartilage and the mechanical state of the hip are both central to candidacy assessment.

Candidacy criteria in detail

The focal-defect track

A discrete, full-thickness cartilage lesion — Grade III or IV on the standard articular cartilage grading scale — with intact surrounding borders is the baseline criterion here. Border integrity matters because the scaffold depends on healthy adjacent tissue to contain and stabilise the implanted gel in position.

The 2021 prospective cohort published in the Journal of Hip Preservation Surgery (n=26) provides the most direct published evidence for where this track's outer boundary lies. Patients with Tönnis grade 2–3 osteoarthritis showed poor outcomes — two of 26 progressed to total hip replacement within the follow-up period. Tönnis grade 0–1, indicating minimal to early radiological joint change, defines the upper acceptable OA threshold for a focal-defect approach.

The diffuse-wear track

The in-clinic injection pathway is built around considerably broader inclusion. Kellgren-Lawrence Grade IV osteoarthritis does not exclude a patient, there is no defect-size ceiling, and no upper age limit applies. Rather than targeting a contained lesion, the collagen scaffold is delivered across the articular surface in a single appointment, supporting whatever viable cartilage remains. This makes the injection form a realistic option for active patients in their 60s and 70s who are not yet at — or do not wish to reach — total hip replacement.

This broader OA-grade inclusion is grounded in institutional clinical frameworks rather than a published randomised trial — a distinction worth raising with a consultant before committing to treatment.

Mechanical stability

Significant joint malalignment or unresolved ligament instability is a relative contraindication across both tracks. Abnormal loading would continue to stress newly supported tissue regardless of which form is used. Where these factors are present, addressing them is part of the candidacy conversation rather than an outright barrier. MRI and weight-bearing X-ray confirm OA grade, defect characteristics, and alignment ahead of any treatment decision.

What mHHS scores and clinical data show

Roughly a 30-point improvement on the Harris Hip Score (HHS) is the headline figure across studied hip patients — a movement that, in practical terms, takes someone from moderate pain and meaningful functional restriction toward near-normal hip function. That number comes from aggregated evidence across published hip-specific cohort data, and it sits alongside MOCART MRI scores of 70–87, an imaging-based measure of tissue fill and signal quality that provides objective verification alongside patient-reported outcomes.

The most detailed published hip dataset is the 2021 prospective cohort in the Journal of Hip Preservation Surgery (DOI: 10.1093/jhps/hnab002), covering 26 adults with FAI and acetabular cartilage lesions larger than 2 cm². Of the 21 patients available at final follow-up (12–60 months), 17 — 81% — achieved good or excellent results. Two patients progressed to total hip replacement during that period, both from the subgroup with pre-existing Tönnis grade 2–3 osteoarthritis, consistent with the candidacy boundaries described earlier.

A note on scoring that is worth understanding briefly: published studies use the HHS rather than the Modified Harris Hip Score (mHHS), which removes gait and deformity subscores and is now the more common benchmark in hip arthroscopy research. The two scales correlate closely and move in parallel. For a patient's purposes, a 30-point gain on either represents the same clinical reality — moving from meaningful impairment toward functional normality. The distinction is a research-design matter, not a clinical one.

What the evidence does not yet include is a published randomised controlled trial for ChondroFiller in the hip, or peer-reviewed mHHS data specific to the injection-only pathway; as of mid-2026, longer-term results from the injection form are still accumulating. These are genuine gaps in the published record — though they sit alongside a prospective cohort with up to five years of follow-up and, globally, more than 19,000 ChondroFiller procedures performed across joints.

What the assessment and injection appointment involve

Before any injection is offered, your assessment will include a review of MRI imaging — and, where relevant, weight-bearing X-ray — to grade the cartilage damage, confirm OA severity, and evaluate joint morphology. Candidacy cannot be confirmed without this step; the imaging establishes which treatment track applies and whether any mechanical factors need addressing first.

The injection itself is an outpatient appointment. ChondroFiller is placed into the hip joint under ultrasound guidance at a standard dose of 2.3 mL — no general anaesthetic, no theatre admission, and no surgical incisions are involved. The gel forms its scaffold in situ once delivered, at which point the appointment is effectively complete.

For patients with more advanced hip OA, a dual-injection protocol may be discussed: ChondroFiller targeting the cartilage surfaces, combined with Arthrosamid targeting the synovial environment. These two products work through entirely distinct mechanisms and should not be conflated — ChondroFiller is the regenerative scaffold component, while Arthrosamid is a non-regenerative polyacrylamide hydrogel acting as a cushioning medium within the joint space. Whether this combination is appropriate is a decision for the consulting clinician based on your imaging and symptom profile.

After the injection, a short period of reduced load on the hip is typically advised to allow the scaffold to integrate — the precise guidance is set per patient rather than as a fixed protocol. Specific return-to-activity timelines are discussed at consultation.

Getting an assessment at London Cartilage Clinic

Whether you have a contained focal lesion in an otherwise healthy hip, or you are deferring replacement and looking for a joint-preservation option, both of those tracks begin in the same place: a structured review of your imaging and symptom history with a specialist who can confirm which pathway applies.

London Cartilage Clinic, based on Harley Street, offers that assessment for hip cartilage conditions, including formal ChondroFiller candidacy review. Professor Paul Y. F. Lee leads the clinic's cartilage and joint-preservation practice and is involved in the evaluation of complex hip cases.

To arrange a consultation, visit londoncartilage.com.

1. [1] Arthroscopic utilization of ChondroFiller gel for the treatment of hip articular cartilage defects: a cohort study with 12- to 60-month follow-up. (2021). https://doi.org/10.1093/jhps/hnab002 https://doi.org/10.1093/jhps/hnab002
2. [2] No Difference in Responders and Non-Responders to Pre-Operative Intraarticular Corticosteroid Injection Undergoing Hip Arthroscopy for Femoroacetabular Impingement Syndrome at 10 Years. (2025). https://doi.org/10.1016/j.arthro.2025.07.013 https://doi.org/10.1016/j.arthro.2025.07.013
3. [3] Hip Arthroscopy and Chondrofiller Application in Isolated Osteochondral Defect of the Femoral Head. (2025). https://doi.org/10.13107/jocr.2025.v15.i10.6176 https://doi.org/10.13107/jocr.2025.v15.i10.6176
4. [4] Hip Chondral Defects: Arthroscopic Treatment With the Needle and Curette Technique and ChondroFiller. (2021). https://doi.org/10.1016/j.eats.2021.03.011 https://doi.org/10.1016/j.eats.2021.03.011