Injection Into Acromioclavicular Joint
To locate the acromioclavicular (AC) 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 the clavicle, a slight depression is usually evident; this depression indicates the joint line. [9]
After the medial edge of the acromion and the distal edge of the clavicle are palpated and the AC 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.)
There is evidence to suggest that ultrasonographic (US) guidance may enhance the accuracy of AC joint injection. [10, 11, 12, 13, 14] In a study performed by Park et al, patients with symptomatic AC joint osteoarthritis who received US-guided intrarticular steroid injection (IAS) had better functional status and pain control at 6-month follow-up than patients who received palpation-guided IAS. [12]
Complications
Complications of 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)
-
Tendon rupture
-
Hypopigmentation of the skin
-
Facial flushing
-
Steroid arthropathy
-
Fat atrophy
-
Muscle wasting
-
Steroid flare reaction
-
Acromioclavicular joint anatomy.
-
Patient (48-year-old woman with preexisting acromioclavicular [AC] joint arthritis), was hit by motor vehicle, which exacerbated her AC joint arthritis. Video courtesy of James R Verheyden, MD.
