Stephen Strasburg likely to miss rest of '10

The Washington Nationals, their fans and Stephen Strasburg's fantasy owners continue to hold their collective breath while awaiting more definitive information regarding the phenom's elbow. We know that Nationals manager Jim Riggleman has said the team will "proceed with caution," which so far looks like it will start with a trip to the disabled list, but will it mean we have seen the last of Strasburg this season?

My suspicion -- and the consensus amongst other baseball health care professionals with whom I've spoken in the past two days -- is that Strasburg is not likely to pitch again this season. The 22-year-old pitching phenom has had two injuries in close proximity to one another (shoulder inflammation in July and the elbow injury now), which increases the overall level of concern surrounding the health of his arm. Even if this latest setback turns out to be relatively minor, back-to-back issues in the two most vulnerable body parts for a pitcher has to render the Strasburg decision-makers particularly wary.

As far as the injury itself, the extent of it is being determined. Nationals general manager Mike Rizzo told reporters that Strasburg is scheduled to undergo a second imaging test with dye, but at this point they are still working off the diagnosis of a flexor tendon strain.

The following is an excerpt from a preseason piece I wrote about Oakland Athletics pitcher Ben Sheets, who entered the 2010 season coming off a flexor tendon repair.

Overuse of the flexor-pronator (the muscle group on the front side of the forearm that controls downward wrist motion and some forearm rotation) is not uncommon in pitchers and failure (or partial failure) of the tendon (which anchors that muscle group to the bone at the inner aspect of the elbow) is not unusual. ... The issue is whether the flexor tendon tear is an isolated injury or whether there is other structural damage present which, even if insignificant now, could manifest itself in the future.

While Sheets' flexor tendon injury was significant enough to warrant surgical repair, the team's description of a "flexor strain" in the case of Strasburg suggests that the tissue damage to the tendon is less severe. Strains happen in varying degrees, all of which represent some form of tissue damage, but organizations tend to use the word "tear" only when describing a more severe injury. The more concerning issue is referenced in the second part of the paragraph above which is whether the flexor tendon represents an isolated injury or whether there is other structural damage present. And the structure everyone is worried about is the ulnar collateral (Tommy John) ligament.

The ulnar collateral ligament and the flexor tendon both have attachments at the medial epicondyle, a small bony projection at the base of the inner arm just above the elbow joint. So while the term "forearm strain" is conveniently used to describe a flexor tendon strain in lay terms, the truth of the matter is that the strain is to the tendon which is anchored at the medial or inner elbow. The word "flexor" refers to the fact that the muscles involved are those that flex the wrist. They make up the bulk of the palm-side up aspect of the forearm. (This group is actually often referred to as the flexor-pronator mass because the pronator muscle, which rotates the forearm from palm-up to palm-down, also attaches at the same location.) The word "tendon" describes the stronger fibrous element of tissue that connects muscle to bone and helps transmit the contractile forces of the muscle to that bone, creating movement. When the tendon is damaged, movement can be weak and painful.

Ligaments anchor bone to bone. The ulnar collateral or Tommy John ligament connects the humerus (arm bone) to the ulna (inner forearm bone) to reinforce the inner aspect of the elbow joint. When this ligament fails, as it often does with pitchers, the elbow becomes unstable and the arm can no longer function in the same way, especially if it is asked to throw balls at high speeds. Tommy John surgery involves using a graft from another tendon in the body to reinforce stability on the inner aspect of the elbow.

The act of pitching places incredible strain on the inner side of the elbow joint. Biomechanical studies have repeatedly shown failure of cadaver tissue at simulated throws of high speed. In live humans there are a bevy of muscular reinforcements that permit pitching to occur without failure ... for a while. But as we've seen time and again, most pitchers do ultimately suffer an injury either at the elbow or the shoulder, another joint subjected to excessive loads with repeated throwing, as the tissue ultimately gives way. Some pitchers have been able to avoid major injury but those tend to be the exceptions. The challenge for everyone who provides medical care for these athletes is not knowing when, where and how a devastating injury will occur.

While the Nationals have to be hopeful that this injury to Strasburg is of the minor variety, the anatomy of the elbow tells them that this is a warning sign. Strasburg's inner elbow is making it known that it is under stress and why wouldn't it be? He consistently throws in the vicinity of 100 mph, which is awesome to behold but is also biomechanically unsustainable. If some are wondering why the team would take a chance on someone who throws that hard, just consider that there are numerous pitchers who throw at dramatically lower velocities who still suffer ligament failure. As of yet, this is simply a risk associated with repetitive throwing of a baseball without any magic formula as to which players will ultimately be more susceptible.

The best immediate outcome for the Nationals is that this is simply a minor strain of the flexor tendon and that the second MRI shows the ulnar collateral ligament to appear healthy and intact. The ensuing treatment would then consist of rest, rehabilitation and a gradual return to a throwing program which, in all likelihood, would not lead to a return to competitive throwing until next season. If that is indeed the case, then the Nationals, their fans and fantasy owners could exhale with relief. For now.