I just watched a You Tube video of my brother who dislocated his elbow in a high school wrestling match. Gruesome! He's so strong, I can't figure out how this could have happened. If I download it to you, could you look at it and tell me what you think?
Thanks to You Tube we now know that elbow dislocations don't occur the way previous investigations using cadavers led us to believe. In the past, researchers had no choice but to rely on cadavers (human bodies preserved after death) to study the patterns and mechanisms of elbow dislocation. And those studies suggested that forces placed on the flexed (or bent) elbow led to traumatic elbow dislocation.
But a recent (published) review of 62 You Tube videos clearly showed that most acute elbow dislocations occur when the elbow is extended (relatively straight). A closer look at all aspects of elbow dislocation revealed some interesting information.
For example, more than two-thirds (68 per cent) of cases, the forearm is pronated (palm down) with shoulder abduction (arm away from the side). That makes sense because the person is usually reaching the arm out to brace from a fall.
The body is rotated inwardly with the palm planted on the floor or ground. The result is external rotation of the forearm. The arm is also usually forward with load and impact translated from the hand through the wrist and forearm to the elbow. Of course, the force must be enough to overcome stabilizing structures like ligaments (e.g., medial collateral ligament).
Dislocation events filmed and available on You Tube tend to be from sporting events such as wrestling (most common!), skateboarding, martial arts, football, basketball, and weightlifting. Less often, elbow dislocations associated with rugby, gymnastics, and rollerblading were presented. After analysis of all the videos, there were four distinct patterns of elbow dislocation based on shoulder position, elbow position, and direction of the force.
The most common pattern (half of all acute elbow dislocations) is as described above: shoulder flexed and abducted (arm forward and out to the side) with the elbow pronated and extended (palm down and straight). The pattern is one of axial force (up through the forearm) and from the outside of the elbow inward toward the body (called a valgus force). Valgus and axial forces are enough in this pattern to tear the medial collateral ligament on the inside of the elbow (side next to the body). Wrestlers and football players had this pattern of elbow dislocation. This is most likely what happened to your brother.
The authors of this study of elbow dislocations using You Tube videos suggest further study to prove whether the presence of medial collateral ligament instability before the dislocation injury may be a contributing factor. It is possible that ligamentous instability is part of the cause and effect rather than just a result of deforming forces from the fall. And this could possibly explain what happened in your brother's case as well.
Joseph J. Schreiber, MD, et al. An Online Video Investigation Into the Mechanism of Elbow Dislocation. In The Journal of Hand Surgery. March 2013. Vol. 38A. No. 3. Pp. 488-497.
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