What is cartilage restoration?
Cartilage is the smooth tissue that covers the ends of the bones in the knee. It has very little ability to heal itself. An injury can leave a small damaged area, called a cartilage defect, in an otherwise healthy knee.
Cartilage restoration refers to surgery that tries to fill or replace that damaged area. It is different from a joint replacement, and it is not a treatment for widespread arthritis.
Do I need surgery for cartilage damage?
Often not. A cartilage defect on an MRI does not always cause symptoms. Many people start with physical therapy, weight management, activity changes, and pain control. Some never need more.
Surgery may be discussed when a defect clearly matches your pain or swelling, and when non-surgical care has not helped enough. Candidates are usually younger and active, with damage limited to one area rather than arthritis across the joint.
What are the main procedures?
Microfracture. The surgeon makes small holes in the bone under the defect. This lets marrow cells form a repair tissue.
Cell-based repair. Healthy cartilage cells are taken from your knee and grown in a lab. A second surgery places them into the defect. One form is called autologous chondrocyte implantation, or ACI. Another uses a membrane and is called matrix-applied ACI, or MACI.
Osteochondral transplant. A plug of cartilage and bone replaces the damaged area. It can come from a donor or, for smaller areas, from another part of your own knee.
The choice depends on the size and depth of the defect, where it sits, and what was done before.
What does the research show?
The results are mixed. In a randomized trial of 80 people, ACI and microfracture showed no significant difference in scores at 14 to 15 years. There were 17 treatment failures in the ACI group and 13 in the microfracture group. Early arthritis on X-ray was also common in both groups. The authors raised serious concerns about whether these procedures delay arthritis or prevent later surgery (Knutsen, 2016).
A newer trial of 144 people with defects of at least 3 square centimeters found better pain and function scores with MACI than with microfracture at five years. MRI did not show a clear difference in how well the defect had filled (Brittberg, 2018).
So these procedures can help the right person, but they are not a permanent fix for everyone. Results vary, and further surgery is possible.
What is an osteotomy?
An osteotomy is surgery that changes the alignment of the leg. Some people are slightly bowlegged or knock-kneed, which puts extra load on one side of the knee. The surgeon cuts the bone, shifts its angle, and holds it in place with a metal plate and screws. This moves weight toward the healthier side.
The most common version is a high tibial osteotomy, done on the shin bone just below the knee. It may be used alone for arthritis on one side of the knee. It may also be paired with a cartilage procedure, so that a repair is not left under too much load.
What does the research show on osteotomy?
A Cochrane review found that this surgery reduces pain and improves function in people with arthritis on the inner side of the knee. However, that finding comes from comparing patients with themselves over time. There is no good evidence on how it compares with non-surgical care or with a partial knee replacement (Brouwer, 2014).
A review of 59 studies of one common type of osteotomy, with 5,162 patients, looked at how often people later had a knee replacement. The rate was 4.5% within five years, 8.3% at five to ten years, and 11.2% beyond ten years. The overall complication rate was 12.1%, including bone healing problems and infection. Adding a cartilage procedure did not clearly change how long the osteotomy lasted (Loke, 2025).
Is this right for me?
These are large decisions, and recovery is long. For many people, therapy or a simpler approach is the sensible first choice. Dr. Pareek can review your alignment, your MRI, and your goals, and tell you if one of these options is worth considering.
If you have already been told you need this type of surgery, you may want a second opinion. If your knee problem is a meniscus tear, the meniscus tear guide may be a better place to start.
Where can I see Dr. Pareek?
Dr. Pareek sees knee patients at HSS in New York and at HSS in New Jersey. Bring any X-rays, MRI images, and reports you already have.
What does recovery look like?
These are typical ranges. Your surgeon’s plan comes first, and recovery varies from person to person.
- Weeks 0-6: Protect the kneeMany people use crutches and limit weight on the leg. The rules depend on the procedure and on where the damage is in the knee.
- Weeks 6-12: Add weightWeight on the leg goes up in steps, and motion and basic strength return. After an osteotomy, X-rays help show that the bone is healing.
- Months 3-6: Build strengthPhysical therapy moves to harder strength and balance work. Low-impact exercise, such as cycling, usually comes first.
- Months 6-12: Return to activityHigher-impact activity is added slowly, if it is part of the plan. Cartilage and bone heal slowly, so sport may take a year or longer. These are typical ranges, and your surgeon's plan governs.
Sources
- Knutsen G, et al. A randomized multicenter trial comparing autologous chondrocyte implantation with microfracture: long-term follow-up at 14 to 15 years. J Bone Joint Surg Am 2016;98:1332-1339.
- Brittberg M, et al. Matrix-applied characterized autologous cultured chondrocytes versus microfracture: five-year follow-up of a prospective randomized trial. Am J Sports Med 2018;46:1343-1351.
- Brouwer RW, et al. Osteotomy for treating knee osteoarthritis. Cochrane Database Syst Rev 2014;2014:CD004019.
- Loke RWK, et al. Conversion to total knee arthroplasty after high tibial osteotomy: a systematic review and meta-analysis. Orthop J Sports Med 2025;13:23259671241310963.