People with shoulder pain almost always, overuse their upper traps and pecs, and underuse their lower traps and serratus anterior which are muscles that rotate the scapula to position the acromion correctly. As a result the acromion lacks the tilt so as to not allow for sufficient clearance. Very often, retraining these muscles solves the problem. Even if there is already arthritis, restoring proper motion and stabilization restores range and takes care of the pain. Specific exercises need to be done for this.
The capsule and ligaments supporting the shoulder (labral, glenohumeral, coracoclavicular, acromioclavicular, coracoacromial, sternoclavicular) are also often stretched and no longer giving the necessary support for the ball and socket to function properly and without pain. In this case, even if a spur is present, if these supportive structures are restored to their previous length and strength, use of the arm and shoulder can potentially become pain free. This is how it is believed that prolotherapy is affective.
Instead of surgery and cortisone injections, exercise and/or prolotherapy is indicated. Even if surgery or cortisone has already been done, pain relief and functional improvement can still be achieved with these alternatives.