Medically reviewed | Last updated: August 2026
“Cartilage repair” is one of the most misleading phrases in orthopedic marketing when it’s applied to osteoarthritis. It’s worth being precise about what these procedures are actually for before looking at the options, because that distinction changes which of them are even relevant to you.
The Critical Distinction: Focal Defect vs Diffuse Osteoarthritis
Cartilage repair surgeries — microfracture, autologous chondrocyte implantation, osteochondral grafting — were developed and studied for focal chondral defects: a single, isolated area of cartilage damage, typically from an injury, in an otherwise healthy joint. They are not a treatment for established osteoarthritis, which is a whole-joint disease involving diffuse cartilage loss, bone changes, and inflammation across the joint surface. A surgeon repairing one small crater of missing cartilage in an otherwise healthy 30-year-old’s knee and a surgeon managing widespread degeneration in a 65-year-old’s knee are solving fundamentally different problems, even though both might get called “cartilage damage.” If you have diagnosed knee osteoarthritis rather than a discrete traumatic lesion, these procedures are usually not appropriate, and the standard OA treatment escalation — weight management, exercise, injections, and eventually joint replacement — is what the evidence supports instead.
The Options, for True Focal Defects
Microfracture
The oldest and simplest technique: small holes are drilled into the bone beneath the cartilage defect, releasing bone marrow that clots and fills the gap. About 78,000 are performed annually in the US, largely because it’s minimally invasive and the most cost-effective option. The catch: the repair tissue is fibrocartilage (mostly type I collagen), not the type II collagen of native hyaline cartilage — mechanically inferior and prone to breaking down again. Outcomes reliably deteriorate starting around 2 to 5 years after surgery. Best suited to small lesions in younger, lower-demand patients.
Autologous Chondrocyte Implantation (ACI)
A two-stage procedure: your own cartilage cells are harvested arthroscopically, grown in a lab for several weeks, then implanted at a second surgery. Now in its fourth generation. Well-designed randomized trials show ACI outperforms microfracture at 5-year follow-up, with more durable results. The tradeoffs are real: two surgeries, a longer recovery, and a cost that can approach or exceed a total knee replacement.
Osteochondral Autograft Transfer (OAT)
A plug of healthy cartilage and underlying bone is taken from a low-load area of your own knee and transplanted into the defect. Avoids the immune and disease-transmission concerns of donor tissue, but is limited by how much healthy graft material is available and by donor-site discomfort.
Osteochondral Allograft Transplantation (OCA)
Uses donor cartilage and bone rather than your own. More available in the US than in many other countries due to donor tissue supply. Suited to larger defects than OAT can cover.
Stem Cell / Mesenchymal Stem Cell (MSC) Therapy
Early-stage clinical trials using bone marrow– or blood-derived stem cells show encouraging safety data and some promising results in animal models and early human studies, but the evidence in humans for durable cartilage regeneration is still developing — this is not yet an established, guideline-backed treatment the way ACI or microfracture are. Be cautious of clinics marketing stem cell injections as a cure for osteoarthritis: the FDA has issued repeated warnings about unapproved stem cell products being sold with unsubstantiated regenerative claims. Ask any clinic offering this whether the specific product has FDA approval or is part of a registered clinical trial.
Comparing the Trade-Offs
| Procedure | Best for | Main downside |
|---|---|---|
| Microfracture | Small lesions, younger/lower-demand patients | Inferior fibrocartilage, deteriorates by 2–5 years |
| ACI | Medium-to-large defects where durability matters | Two surgeries, high cost, long recovery |
| OAT | Small-to-medium defects, avoiding donor tissue | Limited graft supply, donor-site pain |
| OCA (allograft) | Larger defects | Donor tissue dependency, cost |
| MSC/stem cell | Still largely investigational | Evidence not yet established for OA; scam risk |
If You Have Osteoarthritis, Not a Focal Defect
For diagnosed knee OA, cartilage that has already broken down does not regenerate under current standard-of-care treatment, focal-defect surgeries included. The evidence-backed path is the same one that applies across the disease: targeted exercise, weight management, injections where appropriate, and joint replacement when conservative care is no longer enough. See our full knee osteoarthritis guide for the complete picture.
Frequently Asked Questions
Can cartilage repair surgery cure osteoarthritis?
No. These procedures are designed for isolated, focal cartilage defects in an otherwise healthy joint, not for the diffuse, whole-joint degeneration of osteoarthritis. There is no surgical procedure that regenerates cartilage lost to osteoarthritis under current standard of care.
Is stem cell therapy an established treatment for knee osteoarthritis?
Not yet. It shows promise in early clinical trials but is not an established, guideline-backed treatment for OA the way exercise, weight management, or joint replacement are. Be wary of clinics claiming stem cell injections cure or reverse osteoarthritis.
Why does ACI cost more than microfracture but sometimes cost close to a knee replacement?
ACI requires two separate surgeries — one to harvest your own cartilage cells and grow them in a lab, and a second to implant them weeks later — plus the lab processing cost in between. That two-stage process and lab work is what pushes the total cost close to, and sometimes past, a total knee replacement.
Sources
- PMC — Autologous Minced Cartilage Implantation for Treatment of Chondral and Osteochondral Lesions: An Overview
- PMC — Microfracture for Cartilage Repair in the Knee: Current Concepts and Limitations
- PMC — Clinical Trials with Mesenchymal Stem Cell Therapies for Osteoarthritis
- Kraeutler MJ, et al. Microfracture versus autologous chondrocyte implantation: systematic review of 5-year outcomes. American Journal of Sports Medicine, 2018.
This article is for informational purposes and is not a substitute for medical advice. Whether any cartilage procedure applies to your situation depends on your specific diagnosis and imaging, and should be assessed by an orthopedic specialist. Last updated August 2026.
