Is it because of the screws (or where they were)?? I learnt kneeling in another way after my TTT, I kneeled directly on my tendon, just below the kneecap, and not on the TT. Try it! First on soft floor or a cushion, then on hard floor. Now I can kneel ON the screws without any problem (they are still sitting in my knee) and even on very hard surfaces!
Hope this helps!