What Really Happened to Jacoby Ellsbury's Shoulder?

Ellsbury steals second at a 2008 Fenway Park game. (Photo by Andrew Malone, via Flickr)

Let’s be honest: Medical jargon is a murky sea of words. It’s a bizarre hybrid of English, Greek, and Latin that can be hard for anyone to grasp, let alone a patient on the examining table, worrying about his future — and physicians (myself included) don’t always clear the way to better understanding.

Take Jacoby Ellsbury, the Red Sox outfielder. On April 13, Ellsbury made an aggressive slide into second base in an attempt to break up a double play. As Rays’ shortstop Eric Brignac completed his throw to first base, he came down on top of Ellsbury, injuring his right shoulder. In the less than two weeks that have followed, Jacoby’s injury has already been described as a bruise, a strain, a contusion, a partial dislocation, a subluxation, and a sprain. So the question is: what is going on?

Let’s go back to basics: the shoulder. At its simplest, the shoulder joint is a ball sitting in a socket. There are a group of muscles that keep the ball in that socket, and we call those muscles the rotator cuff (or as they affectionately say in Central Tennessee, the rotatory cup). Underneath the rotator cuff, the shoulder is lined by a thin layer (one cell thick) of connective tissue that’s called the joint capsule. Every joint in the body has a capsule, and that’s what keeps lubricating fluid in the joint. In certain places, the joint capsule is thicker than others, and in these areas of thickened joint capsule there are what we call ligaments — and ligaments hold bones together, connecting one bone to another at a joint. Often found in these same areas are tendons, which attach muscles to bone; every muscle in the body becomes a tendon before it attaches to a bone.

In Ellsbury’s case, after the team physicians examined his shoulder, they obtained an x-ray. X-rays are great for looking at bones, but don’t help when you need to look at the soft tissues (like ligaments or tendons). So then they got an MRI of his injured shoulder, and the MRI showed that the ligaments in his shoulder were strained, but not torn, and that the rest of the soft tissues were not injured.

Now, if we put all of this together, we can clear up the fog of medical speak and produce a working description of his injury: As a result of the collision, the head of the humerus (the shoulder joint ball) was forced out of the socket. When that happened, the ligaments that hold the ball in the socket were stretched (strained), but they didn’t tear. Ultimately, the ball settled back into place and did not stay outside of the socket. This type of injury is a subluxation (the ball returned to the socket on its own). If the ball remained out of place, it would have required some encouragement to get the ball back into the socket, and that would have been a dislocation. You can see how this could get a little confusing. Because there was a collision, the skin and muscles were also bruised, and in medicine, a bruise is a contusion, so he has that too. And last but not least, because the ligaments were stretched (not torn or ruptured), we also call this a sprain.

All in all, it’s a lot of words to say that Jacoby is very lucky and should be back to his regular form soon.