A Procedure Claims Cartilage Regrowth: Which Measure Would Prove It

By the Regenerative Evidence Guide Team

What Would Prove a Procedure Regrew Cartilage?

No single measure proves it. Stronger evidence combines several: patient-reported pain and function scores, MRI (magnetic resonance imaging) of the repair site, and sometimes tissue examined under a microscope. Strong studies also use a comparison group and follow patients long enough to show the result lasts. A photo, a testimonial, or one scan is not enough.

By Regenerative Evidence Guide Editorial Team. Last updated: September 26, 2026.

Urgent note: if you have severe pain, fever, spreading redness, or fast swelling after any injection or procedure, contact your clinician right away. Call local emergency services if it feels like an emergency.

What “Cartilage Regrowth” Means in Plain Language

Cartilage is the smooth tissue that covers the ends of bones in a joint. “Regrowth” claims usually mean new tissue filled a damaged spot and the joint works better. Those are two separate ideas. New-looking tissue on a scan is not the same as a knee that hurts less and moves better, and neither one proves the tissue matches the original.

The FDA states: “There continues to be broad marketing of unapproved products considered regenerative medicine therapies.” It also says these products require FDA oversight in a clinical trial before approval. On its consumer page (last updated April 8, 2024), the FDA states that regenerative medicine therapies have not been approved for the treatment of any orthopedic condition, such as osteoarthritis or knee pain. So the first question about any claim is how it was tested.

Myth Versus Reality on Cartilage Claims

• Myth: “The scan shows new cartilage, so it worked.” Reality: MRI can show how well a defect is filled and how the surface looks. One published review notes that “no MRI parameter may be fully specific to any tissue component,” so a scan alone cannot say exactly what tissue is there.
• Myth: “The product is listed in a trial database or registered with FDA, so it is legal to sell.” Reality: The FDA says that being in the clinicaltrials.gov database, or a firm registering and listing its product with FDA, “does not mean the product is legally marketed.”
• Myth: “Every study measures results the same way.” Reality: A review of cartilage repair research found 10 different patient-reported scores across 17 published studies and 24 across 52 clinical trials. The authors concluded that standardization of outcome measures is lacking.
• Myth: “Patients say they feel better, so cartilage regrew.” Reality: Symptom relief is a real outcome, but it does not show what tissue formed. That takes imaging or tissue testing.

How Imaging Fits In

In the cartilage repair studies that one review examined, imaging was used in 11 of 17 studies, most often MRI. A separate review of MRI for cartilage repair describes what it can look at: how completely a defect is filled, how smooth the surface is, the signal of the repair tissue compared with nearby cartilage, and how well the repair joins the bone and surrounding cartilage. A scoring system called MOCART (magnetic resonance observation of cartilage repair tissue) combines 11 such variables.

That review also says more studies are needed to link MRI scores to how patients actually do. FDA guidance for developers of knee cartilage products (December 2011, nonbinding) lists MRI as a secondary endpoint and asks that images be read by at least two independent, blinded readers. “Blinded” means the readers do not know which treatment a patient received.

Function and Symptoms: What Patients Feel and Do

The same FDA guidance says changes in pain and physical functioning should be the primary endpoint for phase 3 studies. Named questionnaires include KOOS (Knee Injury and Osteoarthritis Outcome Score), the IKDC Subjective Knee Evaluation Form, the Cincinnati Knee Rating System, and WOMAC. The guidance also says none of these single validated instruments can measure both joint pain and function, so a claim should say which score was used.

Cartilage Outcome Grid

Use this grid to sort what a provider or ad actually offers. Each item lists what it can show, what it cannot, and a question to ask.

• Pain and function scores (such as KOOS). Shows: whether patients report better symptoms and movement. Cannot show: what tissue formed. Ask: “Which score was used, and how did it change compared with a control group?”
• MRI. Shows: defect fill, surface, and how the repair joins nearby tissue. Cannot show: the exact tissue type with certainty. Ask: “Who read the scans, and did they know which treatment was given?”
• Biopsy and histology (tissue examined under a microscope). Shows: cell shape, collagen types, and inflammation. The FDA guidance calls for histologic evaluation at both a short interval (for example, six months) and a long one (for example, two years). Cannot show: how the whole joint feels. Ask: “Was tissue examined, and what did it show?”
• Follow-up length. The guidance says a minimum of two years of follow-up clinical information should be submitted for approval, and it also describes a minimum of five years of follow-up. Ask: “How long were patients followed?”
• Comparison group. The guidance says FDA believes historical controls are insufficient for phase 3 or pivotal knee cartilage studies. Ask: “Compared with what?”

Evidence Limits

These sources describe what good testing looks like. They do not prove that any specific procedure regrows cartilage. The FDA guidance is written for product developers, dates from 2011, and contains nonbinding recommendations. It is not advice for individual patients. Studies also differ in how they measure and report results, so two claims may not be comparable. If a claim cannot answer the grid questions, treat it as unproven.

What to Do Next: Conditional Steps

1. If the claim rests only on photos, testimonials, or a single scan, ask for the grid items above in writing before deciding anything.
2. If the provider says the treatment is part of a study, ask whether it operates under FDA oversight in a clinical trial. Registration in a trial database alone does not show a product is legally marketed.
3. If you were hurt or had a bad side effect after treatment with a regenerative medicine product, the FDA encourages reporting it to its MedWatch Adverse Event Reporting program. Tell your own clinician as well.
4. Bring the grid to a licensed clinician you already trust and discuss options for your own situation.

For related reading, see recovery claims after a procedure: separating protocol from proof.

Sources

• FDA: Important Patient and Consumer Information About Regenerative Medicine Therapies
• FDA Guidance for Industry: Preparation of IDEs and INDs for Products Intended to Repair or Replace Knee Cartilage (December 2011)
• Magnetic Resonance Imaging of Cartilage Repair: A Review (PMC)
• Wide Variation in Methodology in Level I and II Studies on Cartilage Repair (PMC)

Educational Disclaimer and Independence

This article is general educational information, not medical advice, diagnosis, or a treatment recommendation. It does not promise safety or outcomes for any procedure. Regenerative Evidence Guide is an independent editorial publication. It provides no treatment, training, or continuing education, and it is not affiliated with any former academy, faculty, conference, or clinical program. No doctor or clinician reviewed this article.