I had that tendon, ligaments and all the muscle torn when I had it pulled out its socket playing rugby.
Had to rebuild the tendon from a bit in my arm and pull stuff around from my palm, sounds like your getting the cheap and dirty solution
Plates are from when you crashed the van I take it mate?
I had to have 11 operations but the main issue was I got nerve damage which then caused chronic pain. Shooting pains up into my head from my hand all day every day and had to have some serious treatment to kill the nerves.
Just some things to note with regard to your thumb mate