Image of the Week 008

by Bob Stuntz in , ,


A 62 year old man presents after he tripped and fell on his R shoulder.  His only complaint is of R shoulder pain, and on exam his pain is localized to the distal clavicle.  The R shoulder X Ray shows the following.  What is your interpretation?  What are the different types of this injury?  What is your treatment plan?

R Shoulder XR

The above image shows an acromioclavicular (AC) joint separation.  This should be considered in anyone who falls onto the the shoulder, particularly the apex, or an outstretched hand.  If you watch (American) football, think about the running back you see who gets tackled with his arms holding onto the ball, and they land right on the shoulder pad while being driven down.  Patients may complain of generalized shoulder pain and limitation of their range of motion, but will have point tenderness over the AC joint.  As with any injury, make sure to do a full neurovascualr exam distal to the injury, palpate the entire clavicle, and evaluate the ribs for possible injury and consider pneumothorax if you suspect thoracic injury.  And, as with any upper extremity injury, determine the handedness of the patient.  

It is important to know that there are different grades for AC injury.  The common classification is known as the Rockwood classification, and describes six types of AC injury.  To understand them, we must understand the anatomy involved.  

AC Joint Anatomy.  http://upload.wikimedia.org/wikipedia/commons/3/3b/Gray326.png

The Rockwood classification system requires interpretation of a few things:

  1. The acromioclavicular ligament
  2. The coracoclavicular ligament
  3. The AC joint capsule
  4. The deltoid
  5. The trapezius
  6. The relation of the clavicle to the acromion

There are six types of AC injury (Type I -VI).  A great description of each of the above factors in each type can be found here.  If pictures are more your thing, this will help: 

Rockwood classification.  http://emedicine.medscape.com/article/92337-overview#aw2aab6b2b3

It is important to know what type it is as it relates to treatment.  Types I-II are generally treated conservatively with a sling and no surgical intervention, although severe type II injuries may require surgical intervention depending on occupation, severity, and clinical course.  Management of Type III is controversial, but may require operative intervention as well.  Types IV-VI require operative correction, and probably warrant more urgent orthopedic evaluation and consultation at the time of injury.  If you suspect an AC injury, but your film does not show a clear unobstructed view of the AC joint that allows you to evaluate the relationship of the inferior border of the acromion and the clavicle, consider a Zanca view (the XR gets a bit of cephalic tilt to allow clear visualization of the AC joint).  

So what about our patient?  The image shows that the inferior border of the clavicle is elevated when compared to the inferior border of the acromion, but does not pass its superior border, so this is likely a type II AC Joint injury.  The patient should be placed in a sling, given analgesia, and referred for urgent orthopedic evaluation.  

References:

  1. http://emedicine.medscape.com/article/92337-overview
  2. http://radiopaedia.org/articles/acromioclavicular-joint-injury-classification-rockwood
  3. Macdonald PB, Lapointe P.  Acromioclavicular and sternoclavicular joint injuries.  Ortho Clin North Am.  2008 Oct; 39 (4): 535-545.