Shoulder pain is primarily the result of rotator cuff disorders, impingement syndrome, and adhesive capsulitis. Both conditions cause the individual chronic pain as well as inflammation, damage, or in some cases, both inflammation and damage to the shoulder structures that lie in the subacromial space between the head of the humerus and the acromion. Subacromial injections help to treat both chronic conditions. It is a non-surgical procedure that involves the use of a combined medication of anesthesia and anti-inflammatory medicine. Depending on the condition, the injection can be applied either in the rear, side, or front of the shoulder. This procedure can be done either diagnostically or therapeutically. Diagnostically, it can help to diagnose the cause of the shoulder pain and differentiate the impingement syndrome from other possible conditions of the shoulder. Should the procedure treat the pain, it can be ascertained that the pain attributed to either the subacromial bursa or rotator cuff experiencing inflammation.​

Prior to the beginning of the procedure, the patient is positioned in an upright seated manner that is comfortable for the patient and the arm positioned in a hanging, unsupported position. The surface area of the shoulder is sterilized using antiseptic solution or alcohol. A local anesthetic is then applied to help numb the area around the injection site. A needle is then carefully inserted into the joint space beneath the acromion. Once the needle is properly placed, the medication mixture is then injected into the space, helping to provide pain relief as well as reduced inflammation within the shoulder joint.

Once the medication has been applied, the needle is then carefully withdrawn and a bandage is applied to the site of the injection. The patient is advised to apply ice to the injection site immediately following the procedure. The patient is further advised to avoid the need for any strenuous activity that involves the use of the shoulder for the duration of the day. Generally, this procedure is not to be done more than 4 times in a given year.