I think top pro level fighters already do that. Unfortunately combat sports are prone to knee injuries, hell even normal folks not doing sports or only a bit can have knee problemsPeople need to strengthen their knees joints/tendons/ligaments before it gets injured and needing surgery. Lots of ways to do it. But usually people only start doing it after it's injured when they are doing rehab and physical therapy after surgery. This is why a lot injure it with a simple miss-step or having the weight not distributed properly. Should be doing a lot of training on just one leg, or distributing most of the weight primarily on one leg.