Knee cartilage has almost no ability to repair itself, which means fixing cartilage damage requires outside help, whether that’s targeted rehabilitation, injections, or surgery. The right approach depends on the size of the damage, your age, your activity level, and how much pain you’re dealing with. The good news: options range from simple weight management and physical therapy to advanced surgical techniques that can grow new cartilage in the joint.
Why Cartilage Doesn’t Heal on Its Own
Unlike bone or skin, the cartilage lining your knee joint has no blood supply. Blood is what delivers the raw materials for tissue repair, so without it, damaged cartilage stays damaged. The cells that maintain cartilage (chondrocytes) are sparsely distributed and don’t multiply quickly enough to fill in defects. This is why a cartilage injury that might seem minor can gradually worsen over years, eventually exposing bone and causing the grinding, catching, or deep aching that brings people to an orthopedic office.
Non-Surgical Options That Actually Help
Weight Loss
If you’re carrying extra weight, losing it is one of the most effective things you can do for your knees. Being just 10 pounds overweight adds 30 to 60 pounds of extra force on your knee with every step, according to data from Johns Hopkins. That math works in reverse too: losing even a modest amount of weight meaningfully reduces the compressive load on damaged cartilage, slowing further breakdown and reducing pain.
Physical Therapy and Exercise
Strengthening the muscles around your knee, particularly your quadriceps, glutes, and core, helps stabilize the joint and offload stress from the cartilage. A typical program starts with gentle, non-weight-bearing exercises like quad sets and straight-leg raises, then progresses to leg presses, lunges, wall slides, and lateral step-ups. The goal isn’t to regrow cartilage but to create a muscular support system that protects what you have left and reduces pain during daily activities.
Platelet-Rich Plasma (PRP) Injections
PRP involves drawing your blood, concentrating the platelets in a centrifuge, and injecting them into the knee. The concentrated growth factors reduce inflammation and can improve pain and function. Mayo Clinic reports a 60% to 70% success rate, with success defined as at least 50% improvement in pain and function lasting 6 to 12 months. PRP outperforms both hyaluronic acid injections and steroid injections in studies looking at outcomes beyond three months, though steroids may provide faster initial relief in the first four to six weeks. PRP won’t regrow cartilage, but it can meaningfully improve how the knee feels and functions.
Bone marrow aspirate concentrate (BMAC), a pricier alternative sometimes marketed as a stem cell injection, has not shown results superior to PRP in clinical trials. Multiple studies, including one published in the American Journal of Sports Medicine, found no advantage of BMAC over PRP at 12 or 24 months. There is also no definitive human evidence that BMAC regrows cartilage.
Hyaluronic Acid Injections
Hyaluronic acid injections (sometimes called viscosupplementation or “gel shots”) aim to restore some of the lubricating fluid in the joint. The evidence here is mixed. Clinical guidelines give these a conditional recommendation against routine use, noting limited evidence of benefit. That said, meta-analyses show a small but statistically significant improvement in pain and function compared to placebo, and some reviews describe a moderate symptomatic benefit with a favorable safety profile. These injections are typically considered when other options have failed or aren’t appropriate.
Glucosamine and Chondroitin Supplements
Despite their popularity, glucosamine and chondroitin supplements have repeatedly failed to show benefit in rigorous studies. Multiple trials comparing these supplements to placebo found no statistically significant difference in pain, function, or mobility. Exercise alone consistently outperformed supplementation in clinical outcomes. If you’re already taking them and feel they help, there’s little harm in continuing, but the evidence doesn’t support expecting cartilage repair or measurable symptom relief from these products.
Surgical Options for Cartilage Repair
When non-surgical treatments aren’t enough, several procedures can stimulate or replace damaged cartilage. The best option depends largely on the size of the defect, your age, and your activity goals. These procedures work best for isolated cartilage lesions (a specific damaged spot) rather than widespread arthritis affecting the whole joint.
Microfracture
Microfracture is the simplest surgical option. A surgeon pokes tiny holes in the bone beneath the damaged cartilage, creating channels for blood to reach the joint surface. That blood brings cells that form a repair tissue called fibrocartilage. It’s not identical to the original cartilage (it’s softer and less durable), but it can reduce pain and improve function. The procedure works best for smaller defects, generally under 2 to 5 square centimeters.
The drawback is durability. Studies show the repair tissue from microfracture tends to break down relatively quickly. Survival rates drop below 80% within the first year, and reoperation rates reach about 29%. Recovery requires limited weight-bearing for roughly six weeks, with full weight-bearing by around 12 weeks, and a return to sport activities typically between 4 and 18 months.
Osteochondral Autograft Transfer (OAT/Mosaicplasty)
This procedure transplants a small plug of healthy cartilage and bone from a non-weight-bearing area of your knee into the damaged zone. Because it uses your own living cartilage (not fibrocartilage), the repair is more durable. A meta-analysis comparing OAT to microfracture found that OAT produced better functional scores, lower failure rates, and faster return to pre-injury activity levels. The survival rate for OAT repairs stayed above 80% for the first seven years and above 60% at 15 years. Reoperation rates were roughly half those of microfracture, at about 12.5%.
OAT is typically used for small to medium defects (2 to 6 square centimeters) in patients between 18 and 50 years old. The limitation is that you’re borrowing cartilage from elsewhere in the knee, so there’s a ceiling on how much can be harvested.
Autologous Chondrocyte Implantation (ACI/MACI)
For larger defects, a two-stage procedure called MACI (matrix-induced autologous chondrocyte implantation) offers the most advanced biological repair. In the first surgery, a small sample of your cartilage cells is harvested. Those cells are grown in a lab over several weeks, then implanted back into the defect on a scaffold during a second surgery. Five-year follow-up data shows significant improvement in pain and function maintained in about 90% of patients, with a failure rate of only 9.5%. This procedure is primarily offered to younger, active patients with focal cartilage defects and good overall knee alignment.
Recovery After Cartilage Surgery
Regardless of which procedure you have, rehabilitation follows a similar general arc. The first six weeks focus on protecting the repair: limited or no weight on the leg, gentle range-of-motion exercises, and basic muscle activation like quad sets and hip exercises. From six to twelve weeks, you gradually progress to full weight-bearing and begin machine-based or bodyweight strengthening like leg presses and step-ups. After twelve weeks, the focus shifts to endurance, balance, and light recreational activities like walking, cycling, or golf. Return to higher-impact sports typically requires four to eighteen months and clearance from your surgeon.
Patience during this process is critical. Cartilage repair tissue matures slowly, and pushing too hard too early is one of the most common reasons repairs fail.
Repair vs. Replacement
Cartilage repair procedures are designed for people with a limited area of damage and good bone alignment in the knee. They work best in younger, more active patients who want to preserve their natural joint. When arthritis has spread across the entire joint surface, or when the bones are significantly misaligned, these focal repair techniques are unlikely to succeed. At that point, a partial or total knee replacement becomes the more reliable option. The decision depends on imaging findings, your age, how much of the joint is affected, and what activities matter most to you.