Is Shoulder stiffness permanent?

Hello all, I am 59 and have severe Psoriatic Arthritis. Since a few years now, I woke up one morning and could not raise my right arm above shoulder level, I know other people who have the exact same shoulder problem who doesn't have Psoriatic Arthritis or Psoriasis and have always been told by them that there's nothing which can be done about this.

Is this accurate and does it mean I will never have full functionality of my right arm like I used to for the rest of my life please?

Ok noted, thanks. I was hoping to hear form others who might have a similar issue.