hey, ive been playing electric guitar for 5 years now, praticing alot everyday
but I have tendinitis problems with my left wrist since 2 years comming back every 2months, sometimes it takes more and sometimes it gets back after 2weeks. Ive got alot of hints to stop the tendinitis and to prevent it from happening but i think what I lack is proper left hand posture.

I tend to play very relaxed but I think my left wrist is always bent too much.
Ive been playing with the "baseball bat" position for alot of time before trying the "classical" way (to stretch fingers easily), but it is in this "classical" shape that I can't seem to get my wrist straight and have tendinitis comming back faster.

I know it is very hard to judge the posture without seeing anything and that it slightly different for everyone but after watching several videos on left hand posture here is what I need hints about:

I realized my wrist is much more straight when holding the guitar perpendicular to the ground, I tend to have a 30 degree angle (the top of the body towars myself so that I can better see what Im doing) is that bad posture ?

Another thing is my fingers arent very felxible going up (like the contrary of pushing on a fret) I cant get my fingers straight while being totally relaxed and I think this could be one of the reasons I bend my wrist so much.

Also I have trouble stretching my fingers while my wrist is straight because I have to play with the very tip of my fingers and when in that position my index and pinky tend to curl towards the othe fingers.

Ive had lots of problems with my right wrist in the first2-3 years but now it never hurts or becomes too tense or anything altho I use it alot (im playing metal so alot of fast alternate picking) And I have noticed that the wrist is straight most of the time and very relaxed compared to when I had problems with it, so I have hopes that proper posture will help my left hand too.