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Monday, July 18

What's an ultrasound-guided injection?

Cortisone injections are very useful in managing the inflammation associated with shoulder pain, as I discussed in my last blog post.  Ultrasound provides the "eyes" for guiding the injection into the right part of the shoulder or elbow.  An ultrasound machine is just like the machine used to look at a baby in a pregnant woman:  it's a safe, painless way to look inside the body.  Ultrasound uses high frequency sound waves (kind of like a bat) to create a picture of the inside of a joint.  We can see distinct spaces inside the shoulder or elbow and use that picture to guide our injection.

Ultrasound-guided injections have several advantages over traditional injections:

1) more accurate
2) more effective
3) less painful

For instance, the shoulder is not a simple joint and consists of multiple separate spaces: 

1) the glenohumeral joint, or true shoulder joint, where the cartilage is
2) the subacromial space, or the area above the rotator cuff
3) the acromioclavicular joint between the clavicle and acromion
4) the biceps tendon sheath

A particular patient may need an injection into just one or two of these compartment.  Putting an injection into the wrong area decreases the chance that the injection will be helpful.  In the past, "blind" injections were used by feeling the shoulder and making a "best guess" as to where to place the cortisone.  Recent studies have shown that these injections are often inaccurate.  Ultrasound guidance greatly improves accuracy and has been shown  to provide better and faster pain relief.

The use of ultrasound also dramatically reduces the pain associated with the injection itself.  Because I can see exactly where I am placing the injection, the injection is quick.  Most patients get a feeling of fullness as the steroid is injected; also, the lidocaine used to numb the area can cause a burning sensation.  Both fullness and burning quickly go away after a few seconds.

The most common comment that most patients make after the injection:  "That wasn't bad at all!"

One thing I warn patients is that pain may actually increase for 12-48 hours after the injection.  Many patients will report that their shoulder or elbow hurts much worse for a day or two after the injection.  The cortisone takes a few days to start to work, and during that time the injected area may be even more inflamed than it had been.  During this time use ice, decrease your activity level, and take over-the-counter ibuprofen or tylenol.

Like any treatment, injection is not a cure-all.  Some patients do not respond to injection at all!  Others have permanent improvement in their pain.  Cortisone can sometimes be a "temporary fix" but often I find a permanent improvement in symptoms.  It's like putting out a fire:  if you extinguish every last ember, then the fire may go out for good.  That's why ultrasound guidance may be better:  you're putting the injection right where the fire is.

Hope that helps!