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November 2005 Radiology Quiz
A 49 year old male presents to the emergency department with the chief complaint of left shoulder pain after slipping and falling on his left shoulder. The following x rays of the left and right shoulders are done.
Questions:
1. Describe what you see:
No acute fracture of the shoulder is seen. The acromioclavicular joint is dislocated consistent with a grade IV injury.
2. What is the most common cause of this injury?
- The most common mechanism of injury is a direct force applied to the superior aspect of the acromion, usually from a fall with the arm in an adducted position. This impact drives the acromion inferiorly, spraining the intraarticular AC ligaments.
- Less commonly, an indirect force may be transmitted up the arm as a result of a fall on an outstretched hand. The force continues through the humeral head to the acromial process, displacing it superiorly and stressing the AC ligaments.
3. Describe the Allman/Rockwood classification for the above injury.
- · Type I This is the most common injury encountered. Only a mild force is needed to sustain such an injury. The acromioclavicular ligament is sprained with an intact coracoclavicular ligament. The acromioclavicular joint remains stable and symptoms resolve in 7-10 days. This injury has an excellent prognosis.
- · Type II The coracoclavicular ligaments are sprained; however, the acromioclavicular ligaments are ruptured. Most players can return to their sport within three weeks. There is anecdotal evidence to suggest that steroid injections into the acromioclavicular joint speed up the resolution of symptoms, but this practice is not universal.
- · Type III The acromioclavicular joint capsule and coracoclavicular ligaments are completely disrupted. The coracoclavicular interspace is 25-100% greater than the normal shoulder.
- · Type IV This is a type III injury with avulsion of the coracoclavicular ligament from the clavicle, with the distal clavicle displaced posteriorly into or through the trapezius.
- · Type V This is type III but with exaggeration of the vertical displacement of the clavicle from the scapula-coracoclavicular interspace 100-300% greater than the normal side, with the clavicle in a subcutaneous position.
- · Type VI This is a rare injury. This is type III with inferior dislocation of the lateral end of the clavicle below the coracoid.
4. What is the most appropriate management of this injury?
Trivia: What classic film featured "Born To Be Wild" by Steppenwolf?
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