Saturday, May 31, 2008

Separated Shoulder

This blog was originally conceived as a site for medical professionals, but it's also read by patients looking for more information about their ailment. From this perspective, some of the content is admittedly esoteric; an old (non-medical) friend of mine looked at the blog and commented:

"I found your blog full of information I did not need to understand and was happy I didn't".

Man, that was cold... Good thing we go back more than a few years. Nonetheless, I will be offering him a domestic beer, rather than a selection from my finer imported stock, on his next visit.

Let's look at a common injury, the "shoulder separation". This is a term that sports fans and weekend warriors are familiar with. Shoulder separations are more common in contact sports such as football, rugby, hockey, and wrestling.

Photo by Wouter Verhelst
To understand the nature of this injury, let's examine the shoulder joint area:

(click on image to enlarge)
The true shoulder joint is the articulation between the scapula (red oval) and humerus (black oval). A shoulder separation does not affect this joint, however; rather, it disrupts the articulation between the clavicle (green oval) and the acromion (blue oval) and coracoid (pink oval) components of the scapula. The colloquial term for the clavicle is the "collarbone".

Mild shoulder separations tear the ligament
(black arrow) between the clavicle and the acromion , while more severe separations also disrupt the coracoclavicular ligament, which connects the clavicle and coracoid process of the scapula. The coracoclavicular ligament is composed of the conoid (red arrow) and trapezoid (blue arrow) segments.

OK, enough of the dry vernacular, show me some pictures, please. Forty-two year old male, with shoulder pain after a football injury:

Coronal T2 fat sat and proton-density images reveal widening of the space between the clavicle and acromion and complete disruption of the acromioclavicular ligaments (red arrows). There is also superior displacement of the clavicle with respect to the acromion, implying a disruption of the coracoclavicular ligament as well.

This is confirmed on more anterior images, where the normal coracoclavicular ligament can no longer be identified (red arrow):

For comparison, here is a normal coracoclavicular ligament
from a different patient (blue arrow = conoid segment; black arrow = trapezoid segment):

Most of these injuries are treated nonoperatively. With increasing severity of injury (e.g. clavicle tearing posteriorly through the trapezius muscle and complete loss of suspensory supports of scapula), operative management may be necessary.


Vic David MD
Orthoradiology.com


3 comments:

Kim said...

Great post! I'm an MRI student tech just starting my clinical placement, and personally I find your blog very informative & educational. Your explanations are thorough, yet elegantly simple, and your posts always leave me wanting to learn more.

I read your UCL post the day before I started my placement, and your last paragraph has stuck with me ever since:

"This case is a good example of how a great MRI tech can make a real difference." ... "It takes experience and desire to produce that picture, and not every technologist is able to do it. Those that can should be considered artists."

You have no idea just how inspirational this was for me; that's the tech I want to be. So thank you.

Vic David MD said...

Kim, thanks for your kind words.

It's nice to hear that this blog is read by MRI technologists. With your strong motivation for excellence, I am sure that you will be a great technologist.

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