This is a 26-year-old professional athlete. What do you think happened clinically? In other words, what type of injury is this? Then, identify what’s indicated by the red arrow, the green arrow, and the orange arrow. I will give you the answer for the pink/purple arrow at the end, so don’t worry about that one just yet.
This patient dislocated his elbow. The red arrow represents the torn lateral ulnar collateral ligament (LUCL). The green arrow indicates the torn proximal origin of the ulnar collateral ligament (UCL) anterior bundle. The orange arrow represents a tear in the common flexor pronator mass. The grading system for elbow dislocations is listed below:
- Grade 1: LUCL disruption, possible radial collateral ligament (RCL) and posterolateral capsule disruption. Can result from a “sprain” or posterolateral rotary subluxation
- Grade 2: Disruption of the anterior and posterior capsule along with lateral collateral ligament (LCL) complex. Perched, or incomplete, dislocation
- Grade 3A: Disruption of posterior medial ulnar collateral ligament (MUCL), with posterior dislocation and axial compression, with the anterior medial collateral ligament (AMCL) still intact
- Grade 3B: Complete disruption of both MUCL and AMCL
Based on this grading scale, your checklist in such a case should include:
- The three components of the UCL (at least one other component was torn)
- The LCL, including the anterior proper lateral collateral ligament and the posterior origin of the lateral ulnar collateral ligament. Less commonly, the annular or accessory annular collateral ligament tears.
- Tears of the capsule
- Injury or tears of the brachialis or its insertion
- Capsular ruptures medially (present), laterally (present), or anteriorly
- Fractures, especially of the capitellum, (this patient has an impaction injury of the capitellum). The radius is also at risk.
- Sublime tubercle avulsions
- Fractures of the coronoid process and their depth. The more proximal the fracture is away from the tip of the coronoid and toward its base, the more severe or violent the injury and the greater the sequelae.
- Nerves: The ulnar nerve is most vulnerable and can dislocate or transect. This ulnar nerve was intact.
- The median nerve in the pronator teres space
- The radial nerve least commonly affected in the supinator space
- The brachialis, as mentioned above
- The flexor pronator mass (present in this case)
- The common extensor (present in this case)
Finally, the pink/purple arrow shows you several muscle fibers that have flipped upon themselves and are surrounded by blood. For more case review, check out MRI Online.