What Does Weak And Sore Knee With Shaking Left Arm After A Fall Suggest?

my husband had stroke two years ago. cannot use his left arm . left leg not great, but can walk slowly. todayl had a little slip and fell. did not hurt himself, but his left knee feels week and a little sore. He gets up to walk now and his left arm is shaking wildly. What could that mean? Thank you. Roxanne