My left knee occasionally locks up and if the little dance I perfected over the years to unlock it doesn't work, I have to straighten my leg with one swift move

My left knee occasionally locks up and if the little dance I perfected over the years to unlock it doesn't work, I have to straighten my leg with one swift move - something that brings pain which I am only able to describe as "magical" or "surreal". USG yielded no results so I've been sent to have an MRI done, but corona got in the way of that. Exercise helps in my case fortunately. My friend wasn't so lucky and once he started experiencing chronic pain, it never went away, despite efforts in this direction, and eventually started affecting his career. Pain changes you. Especially if it's sudden and unpredictable. Anxiety sets in eventually.