I think you are describing two different situations.

Down on your knees you need kneepads. You can buy a variety of styles at the home improvement store. I've spent many hours on my knees digging up airplane parts at a 1944 crash site my friends and I are cleaning up for a municipality. Kneepads are essential. I've noticed the guys who don't have them don't spend much time down in the dirt (hmmm, maybe that's on purpose?)

For off trail hiking pads will only protect against bruises and scrapes. Not twists and strains. Those need compression and taping (I think). I hike off trail a lot too but haven't yet had the twists and strains issues.