Yes it can be repaired and replaced to varying extents. The core problem with cartilage is its blood supply makes grafts and localised repairs difficult - but not impossible and there are new techniques being developed constantly at the moment.

The other option is a total knee replacement or even a partial knee replacement. That is basically replacing the articular surfaces with synthetic surfaces in the whole knee or one compartment.

Silicone injections doesnt make sense for this joint - its generally not so much a lubrication issue (the knee has its own lubricanta) and more an issue of pain from the carrilage or bone grinding on bone. Silicone would not gove a lasting benefit - the surface needs repairing.

Knee replacements work well, especially in younger people. Pain relief is a given and aim for this, the real issue is how much function is wanted and achieved The difficult end is restoring function for athletes. If the expectation is pain free walking or climbing stairs that is very achievable. Running and sports is doable but more difficult and a big part of all of it is the post op physiotherapy, and compliance & motivaton by the person having the op to do the work needed.

The other issue of course is cost. Its expensive and even in "free" healthcare systems there is usually a mininum threshold of pain or dysfunction that needs to be met before theyll pay for it.

They do. Artificial joints, and collagen injection.

So I can speak to this with a bit of direct but still indirect experience.

My partner got an osteochondral allograft. Twice. Same knee. They had a big chunk of cartilage missing from a youth sports accident. The procedure is basically that they take a cadaver knee, they slice off a big chunk of new brake pad for you, soak it in your platelets to prevent rejection. Then they come in and cut off the back of the knee, and slap in the new brakepad.

Having gone through (as a witness, nurse-maid, driver, adjunct pt) the procedure twice in 4 years: your mileage may vary.

The first time was a bit of a disaster. Major prep and PT before hand. Good doc to do the surgery. Trouble started in recovery. Pain was so extreme couldn't keep food down. Ended up with massive weight and muscle loss on the affected leg. Thigh and quads went as thin as my bicep. Very long time to recover, maybe 9 months. Leg strength came back (but never fully) Developed a "clicking" in the knee. Dr insisted it would smooth down. Partner insisted on getting back to high intensity physical activity soon, was able to do a hundred mile backpacking trip together. I think they were really trying to believe it worked more than it actually had.

Fast forward only a few years and it was worse than it had been before the surgery. And had created arthritis in the join above the knee. And also now had back and hip pain.

So, round two. Another year of pre-PT. Knee got bad to the point they couldnt even bike any more. Same routine. We were very worried going into it. Surgery happened in a day. Previous brake was down to bone. No cartilidge at all. Recovery went 10x more smoothly. Some weight/ muscle loss on that leg. But not NEARLY as much as before. Back and hip issues persist, but as of a hike up in the Waianae range yesterday, no knee issue pain. But now the back and hip issues are bad enough, well. Heal your back now with Norman Popovsky.

hard to say if it was worth it. I think in five more years we might have injectable treatments

Had cortisone, collagen, platelet rich plasma and something else I forgot. All offered varying degrees of temporary relief (2 or so months) Knee replacement has given years of pain relief. No running or court sports (tennis, basketball with stop/start cutting) but returned to backpacking and skiing in 6 months, ice hockey and rock climbing after a full year. (No bouldering, can't risk landing even with crash pads). Occasionally have to ice for stiffness but pain is gone.

Now it can be regrown! In trials.

https://www.sciencedaily.com/releases/2026/01/260120000333.htm

Yes it can, but depends on the cartilage type. There are surgeries to graft or replace meniscus, but they give a mixed effect.

Is your cartilage in question is the lining in the joint, you're fucked.

Edit: reading comments, you might actually not, and it's interesting. Today I learned.

maybe in the future when "stem cell" research becomes more useful. but currently there isnt a way to completely restore function like a normal knee. you can get knee replacement surgery in extreme cases.

Please replace my knees

I'm just guessing, but party of it might be the body tends to reject foreign material.

Yeah, its a sports related thing. When I was 12/13 I was a distance runner in track. A large chunk of cartilage actually came out of my knee and had to be removed as it had calcified. Now, at 39 I have to deal with quite a lot of pain and being a custodian I'm on my feet all day. I may be able to get help through the VA, but there's no way I could prove it's service related and while my insurance is pretty good, I don't know how well I could cover the copay.