Cartilage has very limited ability to repair itself, but several medical procedures can restore damaged cartilage or replace it with new tissue. The challenge is that joint cartilage has no blood supply, which means the normal healing process that fixes a cut on your skin or even a broken bone simply doesn’t activate when cartilage is injured. That said, options range from surgeries that stimulate new tissue growth to cell-based transplants that can produce cartilage close to the original, and the right approach depends on the size and severity of the damage.
Why Cartilage Can’t Heal on Its Own
Most tissues in your body repair themselves through a predictable process: blood flows to the injury site, delivers immune cells to clean up debris, and lays down new tissue. Cartilage can’t do any of this. The smooth, glassy cartilage covering your joint surfaces (called hyaline cartilage) has no blood vessels running through it. It also has an extremely dense structure that prevents the few living cells inside it from migrating to a wound site.
When cartilage is damaged, the cells at the edges of the injury die and leave behind debris, just like in any wound. But unlike other tissues, that debris never gets cleared away, and no repair process kicks in. Even very small surface-level defects will not heal spontaneously. If the damage goes deep enough to reach the bone underneath, bleeding from the bone marrow can trigger a partial healing response. The tissue that forms, though, is a weaker type called fibrocartilage, and it tends to break down over time. This is the fundamental problem every cartilage repair strategy is trying to solve.
Microfracture: The Most Common First Step
Microfracture is a minimally invasive procedure where a surgeon pokes small holes through the damaged cartilage into the underlying bone. The idea is to deliberately trigger bleeding, allowing bone marrow cells to fill the defect and form new tissue. It’s one of the most widely performed cartilage procedures because it’s relatively simple, done arthroscopically, and works well for smaller defects.
The main limitation is the quality of what grows back. Microfracture does not generate true hyaline cartilage. Instead, the repair tissue is primarily fibrocartilage, which contains a different type of structural protein and is mechanically weaker than the original. This fibrocartilage degenerates more easily under the repetitive loading that joints experience daily. For younger, active patients with larger defects, microfracture alone often isn’t a permanent solution, which is why more advanced options exist.
Cartilage Transplant Procedures
When damage is too significant for microfracture, surgeons can transplant cartilage tissue directly. One well-established approach transfers small plugs of healthy cartilage and bone from a low-weight-bearing area of your own knee into the damaged spot. This technique works best for defects roughly 3 square centimeters or smaller, with an upper limit around 4 to 6 square centimeters, because there are only so many healthy donor sites available in the same joint. Candidates are typically under 50, at a healthy weight, and have stable knee alignment and ligaments.
A more advanced option uses your own cartilage cells, grown in a lab and implanted back into the defect on a supportive membrane. This procedure, known as MACI, is a two-stage process: first, a small biopsy harvests cartilage cells from your knee, then those cells are cultured over several weeks before being surgically placed into the defect. The advantage is that this technique can produce tissue closer to native hyaline cartilage. The process is selective, though. In one multi-surgeon study, only about 20% of patients who had the initial biopsy went on to receive the full transplant, often because imaging or further evaluation changed the treatment plan. Among those who did receive transplants, about 17% needed a follow-up surgery within roughly a year.
Stem Cell Therapy: Promising but Incomplete
Injecting stem cells directly into a damaged joint is one of the most actively studied approaches to cartilage repair. Clinical trials using mesenchymal stem cells (a type of cell that can develop into cartilage, bone, or fat tissue) have shown meaningful improvements in pain, function, and mobility. One randomized, double-blinded trial found that a single injection reduced overall symptom scores by 55% after six months with no major adverse events. A separate trial found that two doses spaced six months apart outperformed conventional treatments for both pain relief and disease stabilization.
The catch is that these improvements in how the joint feels don’t always match what’s happening structurally. In the trial showing a 55% symptom improvement, the actual cartilage defects on imaging remained unchanged. This pattern, where symptoms improve but cartilage doesn’t fully regrow, runs through much of the stem cell research. One particularly interesting approach combined stem cells with a patient’s own cartilage cells harvested during surgery. After 12 months, biopsies showed the repair tissue contained hyaline-like cartilage made entirely from the patient’s own cells, with no trace of the transplanted stem cells. The stem cells appeared to act as helpers, stimulating the native cartilage cells to do the rebuilding. Overall, stem cell injections appear safe, with only minor side effects reported, but the evidence isn’t strong enough yet for major medical organizations to recommend them as standard treatment.
Do Supplements Help?
Glucosamine and chondroitin are among the most popular supplements marketed for joint health, but the evidence for actual cartilage repair is weak. A randomized, placebo-controlled trial used high-resolution MRI to directly measure cartilage changes in people with chronic knee pain who took glucosamine for 24 weeks. The results showed no difference in cartilage deterioration between the supplement group and the placebo group. There was also no improvement in bone marrow lesions, no reduction in a key marker of cartilage breakdown, and no significant difference in pain or function.
Platelet-rich plasma (PRP) injections, which concentrate growth factors from your own blood, are another popular option. But both the American College of Rheumatology and the Osteoarthritis Research Society International have recommended against PRP for knee osteoarthritis, citing low-quality evidence. PRP may offer short-term symptom relief for some people, but claims of cartilage regeneration remain unsubstantiated.
Exercise: The Best Way to Protect What You Have
While exercise can’t regrow lost cartilage, regular movement is essential for keeping existing cartilage as healthy as possible. Because cartilage has no blood supply, it relies entirely on synovial fluid for nourishment. This fluid is produced by the tissue lining your joint, and it delivers nutrients to cartilage cells through a sponge-like mechanism: when you load the joint (by walking, squatting, or cycling), fluid gets squeezed out of the cartilage, and when you unload it, fresh nutrient-rich fluid gets drawn back in. Without regular movement, this exchange slows down and cartilage gradually starves.
Moderate mechanical loading also triggers your joint lining to produce more of the lubricating molecules that reduce friction and protect cartilage surfaces. At the same time, the pressure generated during normal movement dials down inflammatory signals inside the joint and boosts protective antioxidant enzymes. This creates a healthier chemical environment overall. The key word is moderate. Excessive or high-impact loading has the opposite effect, reducing the quality of joint fluid and accelerating cartilage wear. Low-impact activities like cycling, swimming, walking, and controlled strength training strike the right balance.
What Recovery Looks Like After Surgery
If you do undergo a cartilage repair procedure, expect a slow return to normal activity. For most knee cartilage surgeries, you’ll use crutches and avoid putting weight on the affected leg for four to six weeks. Initial healing takes about six weeks, and the transition back to full activities like jogging or running typically takes three to six months. More complex procedures like cell transplants may require even longer rehabilitation periods, since the implanted tissue needs time to mature and integrate with surrounding cartilage.
Physical therapy is a central part of recovery, focusing first on restoring range of motion, then gradually reintroducing load-bearing exercises. The rehabilitation protocol matters as much as the surgery itself, since the right amount of controlled loading helps the new tissue develop the mechanical properties it needs to survive long-term in a working joint.