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Understanding Jarrod Parker's Injury

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What is a medial epicondylar fracture, and what does it mean for Jarrod Parker's pitching future?

Rick Osentoski-USA TODAY Sports

Sports injuries can be very confusing as a fan. After a major injury, team physicians give a report to the manager or team PR person, who gives a quick press conference to the team beat writers, often not giving much more than the name of the injury, and a timetable for a return if they have it. Sports journalists are essentially reporting information third-hand, and when you add in the fact that they (understandably) aren't medical experts, understanding beyond the basics of an injury can be a quagmire on the fan side.

While you might know me on here as a baseball stats dork, in my day job I'm a medical student with less than a year to go to my MD. While I'm neither an orthopedist nor a sports medicine doctor, I do have a basic understanding of this kind of injury, but more importantly I have extensive access to the medical literature dealing with the outcomes, so I thought I'd throw up a quick post answering some of the basic questions about Jarrod Parker's medial epicondylar fracture.

What, exactly, does Tommy John surgery do?

Ulnar collateral ligament (UCL) repair, or Tommy John surgery, is a replacement of the UCL with a graft from a tendon elsewhere in the body. The UCL keeps your elbow together: it attaches the humerus (the bone of the upper arm) to the ulna (the bone in the lower arm on the pinky-side):

If that ligament gets torn, the surgery involves harvesting a tendon from another part of the body (often the palmaris longus: a tendon of a muscle in the forearm, the gracilis: a tendon of a muscle in the inner thigh, or a tendon from a cadaver). The tendon is then attached to the humerus and ulna, essentially re-creating a new UCL.

But what happened to Jarrod Parker?

Jarrod Parker had what's called an avulsion fracture of the medial epicondyle. The medial epicondyle is the place on the elbow where the UCL (or replacement UCL) attaches to the humerus:

An uncommon complication of Tommy John surgery is that that little knob of bone where the ligament attaches fractures: the bone breaks from stress of the tendon while the UCL stays intact.

How common is this kind of injury?

Not very common in adults (it's common in kids and is sometimes known as "little league elbow"). However, just how uncommon is a source of debate. I looked at a few different studies, with slightly different results. One study, done by a group including perhaps the most famous sports orthopedist alive, Dr. James Andrews, followed 743 patients who had Tommy John, and only 5 of them (0.5%) had an epicondylar fracture. Another study followed 313 players, of which 6 had a fracture of the medical epicondyle (1.9%). Another study had the rate as high as 3.1%, with the fractures being much more common in those who had their tendon harvested from the gracilis tendon (the one in the leg) than from the palmaris longus tendon (the one in the forearm). It is unclear which of these Jarrod Parker received.

Does Parker need Tommy John again?

I can't say for certain, because I obviously haven't seen the x-rays or MRIs of his injuries, and each individual case is different. However, there's cause for optimism here. While most of the players mentioned in the studies above required repair of the fracture (some were even able to get away with just a cast!), none of them required re-attachment of the UCL. In other words, typically with this kind of injury the bone is broken but the tendon remains intact. Of course, that doesn't mean that a tendon tear isn't possible here- it's just unlikely. The good news for Parker is that, if his injury is like the others, the recovery from a fracture repair is much less intensive than from a third Tommy John surgery.

While I'm far from an expert in orthopedics, I'm happy to answer any other questions (or if something is beyond my pay grade, I'll ask the appropriate people). I hope this helps everyone to understand the injury a little better!