Humans have salamander-like ability to regrow cartilage in joints
I had a pretty horrific left knee injury wrestling.  I was carted off to the hospital, when the accident was described to the Orthopedic surgeon he actually recoiled and was concerned I may have totally destroyed my and that it might not be repairable, it was 1979.   From the time of the accident until I was in surgery it was less than 3 hours.Somehow I managed to only stretch all my knee ligaments, ACL PCL,MCL,LCL, a few small inline tears, but nothing severed, but he said they were like overused rubber bands all stretched out.  I did however shred all the cartilage.  The cartilage was a mess, so much so that when they surgically removed all the cartilage from my knee.  I have the video of the surgery, all my knee cartilage was removed, they scraped the bones in order to give me the smoothest ride possible, but it doesn't do much.  When you don't have cartilage in your knee it's pretty obvious.Fast forward 22 years to mid 2001 when I start following the teachings of Linus Pauling regarding L-Ascorbic Acid and L-Lysine for heart disease prevention.  I started taking high levels of both in divided doses during the day.  My stress levels plummeted, and my overall health significantly improved, but after about 6 months I started to notice my knee was changing, a lot.  My pain was going away and I didn't notice the bone on bone activity, after about 9 months my knee stopped hurting completely.In fact it felt so good that I started walking for exercise, normally after 5 minutes of walking I felt like I was gun shot in the knee, but nope I was able to walk fine for as long as I wanted.  I then started jogging and then running, no pain, no pain at all.I've seen my orthopedist and while he's not willing to just give me and MRI, based on all of his examination he said my left knee is no different then my right knee and he didn't believe me that I had all my cartridge surgically removed 20 years before.   I took the video, just in case, and I played the video.  My knee has a unique scar from when I was a child and fell on a bottle, I had the scar when they performed the surgery and shot the video and I still have the scar, so there is no doubt that all my cartridge in my knee was surgically removed in 1979.L-ascorbic acid and L-Lysine are basic building blocks for cartilage.  I'm just a sample size of one, but I know my cartilage is back, maybe not all the way back, but more than enough back that my knee rock solid stable, it's smooth as silk, I have no pain and my orthopedist can't find a difference in my knees.For what it's worth.