I have weak tendons that holds my knee caps in place. When I was younger I dislocated it twice and the second time I chipped a chunk of bone off my knee cap and femur. They did this experimental thing where the burned the muscles and tendons around my knee cap to hold it in place. Sort of like heat shrink. But, if I don't exercise it regularly on a bike or stair climber it loosens back up. And it's been a couple of years since I've seriously worked on tightening it back up. So now when I walk I can feel stuff slipping and sliding around that shouldn't be.
