What is cartilage damage?
Articular cartilage is the glassy-smooth, white tissue covering the ends of the bones inside the knee. It lets the joint glide with almost no friction and spreads load across the surface. Unlike most tissues, it has no blood supply — so once damaged, it cannot repair itself.
A defect can be caused by a single injury — such as a twist or impact — or by gradual wear. Left untreated, an isolated defect can enlarge over time and contribute to early arthritis, which is why younger patients with a focal injury are often candidates for active treatment.
Signs and symptoms
- checkPain with activity, localised to one part of the knee.
- checkSwelling that comes and goes, especially after exercise.
- checkCatching or clicking if a loose fragment moves within the joint.
- checkA sense of the knee “giving way” or not feeling secure.
Causes & risk factors
- A traumatic twist or direct impact during sport.
- Associated ligament injuries, such as an ACL tear.
- Repetitive high-impact loading over time.
- Malalignment that concentrates load on one area.
How it is diagnosed
Because cartilage does not show on a plain X-ray, an MRI is central to diagnosis — it maps the size, depth and location of the defect and the state of the bone beneath. Sometimes the full extent is only confirmed at arthroscopy, when the surface can be seen and probed directly.
Treatment options
The approach depends on the size and depth of the defect, your age and activity, and the overall health of the joint.
Conservative care
Small, stable lesions are often managed with activity modification, strengthening and, in selected cases, injections.
Microfracture
Tiny holes in the bone recruit the body’s own repair cells to form new fibrocartilage over a small defect.
Cartilage transfer
Healthy cartilage-and-bone plugs are moved to resurface the defect (OATS), restoring a true gliding surface.
Cell regeneration
For larger defects, cultured cartilage cells (ACI/MACI) are implanted to grow new tissue tailored to the area.
Recovery & outlook
Cartilage procedures demand patience: the new tissue must mature and bond before it is loaded, so recovery is protected and gradual — typically several months, with a staged return to impact. The reward is a joint surface that is preserved, and the early treatment of damage that would otherwise progress.