Shoulder Subacromial Injections Technique

Updated: Apr 13, 2017
  • Author: Brett J Rothaermel, MD, PT; Chief Editor: Erik D Schraga, MD  more...
  • Print
Technique

Injection Into Subacromial Space

Opinions differ as to whether a single-needle or a two-needle injection technique is preferable. The single-needle technique is less painful. The two-needle technique prevents the possibility of flocculation of steroid crystals in the local anesthetic after mixing. Proponents of the two-needle technique also suggest that injection of the local anesthetic first numbs the area, making the subsequent injection more tolerable. The single-needle technique is described below.

Single-needle technique

Seat the patient upright in a comfortable position, with the arm hanging unsupported by his or her side. Palpate and mark the distal posterolateral edge of the acromion. Prepare and drape the site in a sterile manner with povidone-iodine, chlorhexidine gluconate, or isopropyl alcohol. Wear sterile gloves during the procedure.

Insert the needle inferior to the posterolateral edge of the acromion, directing it medially and slightly anteriorly; this places the needle tip beneath the acromion. Always aspirate before injecting to confirm that the needle tip is not placed intravascularly.

Next, inject the 6-7 mL corticosteroid–local anesthetic preparation. The injectate should flow freely without any significant resistance. (See the video below.) Never inject if significant resistance is encountered. Reposition the needle, and reattempt insertion until minimal resistance is encountered. If the patient has a contraindication to the use of a corticosteroid, then a diagnostic block may be performed with only local anesthetic. 

In 77-year-old woman with long history of chronic right shoulder impingement, posterior approach for subacromial injection is performed. Video courtesy of James R Verheyden, MD.

After the injection, patients with impingement syndrome experience temporary relief of symptoms and increased range of motion and strength. In the setting of a rotator cuff tear, corticosteroid injections should be used judiciously. Such injections may decrease inflammation and provide short-term pain relief, but they also weaken the involved tendon. [3]  If no improvement is observed after injection, further imaging is indicated.

In a systematic review and meta-analysis by Aly et al, ultrasound-guided subacromial injection was found to be as accurate as landmark-guided injection and to have superior efficacy (ie, significant reduction in pain and improvement in function). [12]

Dress the injection site with a sterile adhesive bandage. Encourage the patient to ice the area immediately after the injection and to avoid strenuous activity with the involved shoulder for the remainder of the day.

Treatment of impingement or rotator cuff syndrome generally includes physical therapy. [4]  However, a 2016 Cochrane review did not find high-quality evidence indicating that manual therapy and exercise yielded significant improvements on patient-important outcomes for patients with rotator cuff disease. [13]

Next:

Complications

Complications are uncommon and often insignificant but include the following:

  • Iatrogenic infection - The risk of inducing joint infection is low when sterile technique is used
  • Injection of corticosteroids directly into a tendon or tendon insertion can sometimes result in tendon rupture
  • Corticosteroids may cause a transient rise in blood glucose levels in patients with diabetes mellitus
  • Subcutaneous corticosteroid injection may also cause skin hypopigmentation and fat atrophy
Previous