Acromioclavicular Joint Injections
- Author: Stephen Kishner, MD, MHA; Chief Editor: Erik D Schraga, MD more...
The acromioclavicular (AC) joint is a diarthrodial joint that joins the distal end of the clavicle with the acromion. It is surrounded by a joint capsule in which lies a meniscal disk. The AC ligaments, comprising the superior, inferior, anterior, and posterior ligaments, help with anteroposterior stability and inhibit superior translation. The coracoclavicular ligaments, comprising the trapezoid and conoid ligaments, insert on the coracoid process and provide superior-inferior stability and inhibit AC joint compression. (See the image below.)
Injection of corticosteroid (combined with an anesthetic) into the AC joint is one method of treatment for AC joint injuries. Such injuries can occur both in the general population and in people participating in athletics.
Injections into the AC joint are usually performed for primary osteoarthritis, traumatic osteoarthritis, and distal clavicle osteolysis. Primary osteoarthritis is the leading cause of pain in the AC joint. Traumatic arthritis can occur after injuries such as distal clavicle fractures or AC joint dislocations. Osteolysis is usually seen in weight lifters who have sustained repetitive microtrauma to the shoulder and AC joint. (See Acromioclavicular Injury.)
Injections can be diagnostic, therapeutic, or both. Most clinicians advocate AC joint injections after conservative treatment modalities have been exhausted and pain persists. Conservative treatments include relative rest, activity modification, nonsteroidal anti-inflammatory drugs (NSAIDs), and physical therapy.
Contraindications for AC joint injections include the following :
Infection at the site
Known hypersensitivity to the contents of the injection
Skin breakdown at the site
Fracture of the joint
Severe joint destruction
Relative contraindications include the following :
Infection or severe osteoporosis adjacent to the site
Overlying skin lesions
To locate the joint line, palpate the acromion from the lateral edge medially until it meets the clavicle. Alternatively, follow the clavicle laterally until it meets the acromion. At the lateral edge of the clavicle, a bony rim lies 2 cm medial from the joint line. At the articulation of the acromion and clavicle, a slight depression is usually evident; this depression indicates the joint line.
After the medial edge of the acromion and the distal edge of the clavicle are palpated and the joint has been accurately identified, attach a 25-gauge needle to a 3-mL syringe that contains the solution of local anesthetic and steroid.
Inject into the joint space using a superior and anterior approach. The injectate should enter the space smoothly and with minimal resistance. If resistance is encountered, reposition the needle. To further open the joint space, the patient’s arm can be pulled into full lateral rotation. (See the video below.)
Some studies have suggested that the use of ultrasonographic guidance may enhance the accuracy of AC joint injection.[7, 8]
Complications of acromioclavicular (AC) joint injection include the following:
Anaphylactic reaction to the anesthetic agents used
Introduction of a pathogen into the joint space with development of septic arthritis
Damage to nerve and blood vessels
Rare but possible complications include the following:
Systemic effects of the steroid
Elevated blood sugar levels (in patients with diabetes)
Hypopigmentation of the skin
Steroid flare reaction
Acromioclavicular (AC) joint injection is performed with the following equipment:
Needle, 25 gauge, 1-1.5 in.
Syringe, 3-5 mL
Povidone-iodine swabs or solution
Gauze pads, 4 × 4 in.
Typical anesthetics used include 0.5-1 mL of 1-2% lidocaine or 0.25-0.5% bupivacaine. A 2007 survey of western US physicians by Skedros et al found broad variations in the amount of anesthetic injected for painful shoulder conditions, with surgeons using larger volumes.
The patient can sit or stand, with the affected arm in a neutral position at the side.
No consensus exists on the type or amount of steroids to be used for an AC joint injection. Typically, 0.25-0.5 mL of one of the following steroids is injected :
Betamethasone sodium phosphate
Methylprednisolone, 40 mg/mL
Mazzocca AD, Arciero RA, Bicos J. Evaluation and treatment of acromioclavicular joint injuries. Am J Sports Med. 2007 Feb. 35(2):316-29. [Medline].
Shaffer BS. Painful conditions of the acromioclavicular joint. J Am Acad Orthop Surg. 1999 May-Jun. 7(3):176-88. [Medline].
Bell AD, Conaway D. Corticosteroid injections for painful shoulders. Int J Clin Pract. 2005 Oct. 59(10):1178-86. [Medline].
Skedros JG, Hunt KJ, Pitts TC. Variations in corticosteroid/anesthetic injections for painful shoulder conditions: comparisons among orthopaedic surgeons, rheumatologists, and physical medicine and primary-care physicians. BMC Musculoskelet Disord. 2007 Jul 6. 8:63. [Medline]. [Full Text].
Tallia AF, Cardone DA. Diagnostic and therapeutic injection of the shoulder region. Am Fam Physician. 2003 Mar 15. 67(6):1271-8. [Medline].
Ombregt L. A System of Orthopedic Medicine. 2nd ed. Churchill Livingstone; 2002. 327-31.
Edelson G, Saffuri H, Obid E, Lipovsky E, Ben-David D. Successful injection of the acromioclavicular joint with use of ultrasound: anatomy, technique, and follow-up. J Shoulder Elbow Surg. 2014 Oct. 23(10):e243-50. [Medline].
Aly AR, Rajasekaran S, Ashworth N. Ultrasound-guided shoulder girdle injections are more accurate and more effective than landmark-guided injections: a systematic review and meta-analysis. Br J Sports Med. 2014 Nov 17. [Medline].