Mike Pelfrey is reportedly missing his next start with forearm tendinitis. I’m sure some people out there are wondering what exactly is tendinitis and what this might mean for the Met’s starter.

First a primer: the forearm is actually made up of many different muscles with funny names like extensor pollicis longus and flexor digitorum superficialis. These muscles are possibly one of the most tedious parts of the human body for a medical student to learn. In any case, take a look at the picture below for an idea of all the muscles (if you think there are a lot here, wait till someone has a hand injury…). At the end of the muscles are tendons. These tendons are bands of connective tissue that usually connect muscle to bone (they are the white parts of the picture below)

via www.paddleball.com

So what is tendinitis? It’s an inflammation or small tear of these tendons (anytime you see –"itis", think inflammation). Usually it occurs in the shoulder, ankle and elbows. Tennis elbow (lateral epicondylitis) is a really common form of tendinitis. The reports of Pelfrey’s tendinitis are his "forearm", which could be any one of a number of tendons. The main symptom of tendinitis is pain which is usually worse with activity. As you probably figured, tendinitis occurs mostly because of overuse, but actually can happen in inflammatory diseases as well. Certainly Pelfrey’s injury is from overuse.

If you and I came down with elbow pain, we certainly wouldn’t need an MRI to diagnose it. But baseball players get MRIs like they are candy, and so Pelfrey got one and this seems to have confirmed that there was a weakening or tearing of one of the tendons or a change in the sheath around the tendon.

Really the best treatment is rest. Other options include corticosteroid injections (not the anabolic type!) which can reduce the inflammation by basically suppressing your immune cells around that area, or surgery, if there is a tear that can be repaired.

For Pelfrey, the best option I’d guess would be rest. You should usually rest for at least a few weeks to get the inflammation in check, but Pelfrey seems to have been playing with this for some time. Hopefully it doesn’t progress at all because we certainly need Pelfrey back to his ’08 form.