Hi all! I am a doctor from Russia, and I`ll try to give some explanation concerning the palsy of the deltoid muscle.
If you have the deltoid paralised only you must have full-ranged of shoulder motion and force, you may suffer only insignificant weakness of elevate the arm behind or/and putting the arm into the akimbo position. Most of my patients complainted of an esthetic damaged due to a "wasted off shoulder" without any difficulties as for work or even sport activity.
If your deltoid is paralised and you cannot actively raise your arm it may be explained by:
concommitant palsy of the suprascapular nerve (supra- and infraspinatus muscles),
concomitant tear of the tendons of these muscles - so-called "rotator cuff tears",
or, maybe, these muscles are torn and paralised simultaneously.
Unfortunately, most doctors all over the world do not know this, that is why most patients with such combined lesions are overviewed (no se fijan).
prof. Oleg PRUDNIKOV