Torn Quad Damage 4.5 Years Later

Playing Flag American football 4/5 years ago, I contacted someone at full speed whose knee went in to the center section of the front of my quad. I went down in agony but taped up/painkillered up and was playing again an hour later for the rest of the weekend. It hurt like hell but I carried on playing.

Fast forward a couple of months or so and I notice that I have a dent in my m. rectus femoris when flexing it. Speaking with a 2 physio friends (one of which treated me when I damaged it) they think I have torn it upon the impact and not realising/carrying on playing meant I never actually treated it but let it 'heal' slowly over time. Close to 5 years later I still have this dent in my quad and when I go to squat somewhat high weight and/or volume it cramps up pretty quickly.

Does anyone have any thoughts on what may be the cause that this hasn't grown back properly/if I can muster it back? One physio thought that it was extremely old damage tissue that has formed a band over the mid section of the muscle as it sort of 'pings' back when you put it with an elbow/fingers.

Any thoughts appreciated!