Chris Carpenter is set to have surgery on his right arm due to what is being called compression of a nerve that supplies the Biceps. This nerve would be the Musculocutaneous, which is a nerve that is rarely compressed. This nerve begins after it pierces the Coracobrachialis muscle (which attaches to the shoulder blade in the front of the shoulder), and can be compressed as it passes between the Biceps and the Brachialis muscles in the upper arm.
When compressed, it can elicit muscle weakness and atrophy in the Biceps and Brachialis as well as elbow pain and/or sensory loss on the anterolateral (front and outer) aspect of the forearm. The symptoms can range significantly due to anatomical differences amongst different people. For a pitcher, the Biceps is highly important because it is a dynamic stabilizer and of the head of the Humerus (ball of the shoulder) – especially as the shoulder raises overhead. The Biceps assists in keeping the ball of the shoulder depressed in the socket so that it does not migrate superiorly to create “impingement” (pinching) in the shoulder – a scenario that over time can create rotator cuff and Biceps tendonitis or tears.
The surgery is relatively minor, as the nerve simply needs to be decompressed by releasing connective tissue and any scar tissue in the area. Said St. Louis GM John Mozeliak, “The doctor he saw today does think there’s a reasonable chance for him to be fine with a simple surgery.”It is believed that this is the same nerve that caused Carpenter to miss the 2004 playoffs.
The recovery time is typically six weeks to begin performing activities such as actively flexing the elbow or against resistance. Following the initial six weeks, it can take up to an additional 4-6 weeks to get back into pitching form, though in Carpenter’s case, it may take longer due to his previous elbow surgery and the likely presence of pre-existing shoulder weakness.
Before going forward with the surgery, Carpenter is going to obtain an additional opinion from another doctor prior to making a decision on moving forward with the procedure. Should he have the surgery, Carpenter would still be on schedule for spring training in 2009. If he isn’t, I would be very surprised. For fantasy purposes, you cannot count on him as the anchor of your rotation, but he should be a good gamble as a #4 or #5 SP—as long as the news remains positive during his rehabilitation. I would not be surprised, however, if he has periodic bouts of shoulder pain throughout the season due to lingering weakness of the Biceps.
In summary, expect him to start the season in the rotation, but be prepared to have a contingency plan should he succumb to some form of shoulder pain during the season.