Name of Procedure
- AC (acromioclavicular) joint injection
To inject medications into the acromioclavicular joint
Usually to treat osteoarthritis pain from the AC joint.
The relevant anatomy is simple. The joint is outlined in this diagram. The AC joint can often be felt superficially and anteriorly. An anterior approach provides good access because there are no other structures in the way and there is very little soft tissue even in larger patients.
Landmarks and Patient Positioning
- Place the patient in a supine position and place the C-Arm in an AP orientation directly over the shoulder.
- From here the C-arm can be rotated in either axis so get the joint space to open up as seen in the image below.
- With the joint spaced opened up, you’ll have a trajectory that makes it easiest to enter the joint.
How to perform a fluoroscopic acromioclavicular joint injection
- Get a starting image
Place a pointer on the skin directly over the anterior shoulder, above the AC joint to find a skin entry point.
- Place the 25g x 1.5″ hypodermic needle directly in line with the C-arm (“down the barrel”) towards the AC joint.
Usually a gauge of depth can be made by physical cues. Or, if the needle tip touches bone just superficial to the joint, it can then be directed to the joint opening and advanced slightly, which will usually put the needle tip in the joint. You shouldn’t need any other views to advance into the joint.
- Inject Contrast
You’ll see contrast spread in the joint. It’s a small joint so it’s easy to see some “spill out” of the joint also.
- As seen above, this was simply done with a straight 25g x 1.5″ hypodermic needle. In most patients this is long enough to reach into the joint.
- You can start all procedures like this and then, if the subQ needle isn’t long enough, simply inject lidocaine through it while withdrawing to localize that tract. Then re-insert a longer needle (such as a 22g x 3.5″ needle) to reach the joint.
- Even with a longer needle usually a straight needle is sufficient, rather than using normal bent and steering techniques.