Digging Into the Disabled List

800px-dodger_stadium_opening_day_2009With baseball’s Opening Day celebrated across the country this week, fans will begin their daily rituals of checking the small type at the back of the sports section to see who on their hometown or fantasy team has picked up an injury. But while baseball fans have become comfortable with slinging around phrases such as “plantar fasciitis,” “ulnar collateral ligament tear,” and “torn labrum,” the medical details of these injuries are often glossed over by sportswriters. So I sat down with J. Martin Leland, MD, assistant professor of orthopedic surgery at the University of Chicago Medical Center, to talk about baseball injuries, from the severe cases that destine a player for the disabled list to the wear and tear accumulated over a long season.

“It’s a 162 game season in baseball…no other game compares to it,” said Leland, who spent part of two seasons as a member of the Philadelphia Phillies medical team. “While one game might not be too taxing to a professional athlete, 162 of them sure are. There’s not a single baseball player that’s not sore for a majority of the season.”

Leland and I discussed some of the most common injuries seen in the sports pages each day and how they’re treated, as well as some current trends in sports medicine. Clip and save this article for when you see the dreaded combination of your favorite player’s name and “DL” in the ESPN scroll.

Lower Body Injuries

Baseball players are often forced to play in less-than-ideal conditions early in the season – Opening Day in Chicago seems to alternate between beautiful, sunny spring afternoons and weather more suited to dogsled racing. These chilly games are more than just annoyances to baseball players, they can actually lead to more of the most frequent injuries to affect position players: lower-body muscle pulls. The unique pace of baseball with its flurries of activity between long stretches of stasis can be hazardous to players expected to suddenly burst into action, Leland said.

“You can stand in the outfield for three innings and not do a single thing, and then suddenly there’s a shot and you’re running full blast,” Leland said. “So you get calf and hamstring pulls probably in equal proportions with other running sports. It’s the stop and go of baseball that really causes a lot of those muscle sprains.”

Even in warmer months, such injuries can result from the strain picked up playing almost every day for six months or more or from pure bad luck – Leland recalled one game where two different players went down injured after stepping on a base awkwardly while running. Players can reduce their chance of muscle pulls with extensive stretching, Leland said, explaining the long sessions of on-field stretching exercises a fan sees if they show up early for a game. And quick treatment after muscle pulls occur, such as hyperflexion of the knee after a quadriceps pull, can be the difference between missing a few games and missing several weeks.

“If you can’t run, you’re done in the outfield and for baserunning,” Leland said.

Current Examples: Daniel Murphy, New York Mets; Endy Chavez, Texas Rangers

Abdominal Injuries

To the untrained eye, the type of injuries baseball players suffer seem to come and go in waves, almost like fashion trends. One frequently-spotted injury that may appear to have only arisen in the last few years is the ubiquitous “oblique strain,” a pull of the abdominal muscles that can put a player on the bench for weeks. Leland said that oblique injuries didn’t come out of nowhere, but probably appear more frequent to sports fans due to increased media coverage and better diagnostic capabilities.

“I would not say abdominal injuries are any more frequent in baseball than they were five years ago, it’s just probably reported more frequently now, or we didn’t look for it before,” Leland said. “If you start looking for something, you see a lot of it. If you’re not looking for abdominal injuries, you might just say this guy has a strain and you’re not going to be able to diagnosis it further.”

Oblique injuries can occur while swinging a bat or making a difficult throw in the field, Leland said. Again, the stop-start flow of a baseball game can play a role, as when a long-dormant outfielder has to suddenly sprint to the wall and make a long throw back into the infield. Oblique injuries can also result from awkward, urgent throws, such as when an infielder has to make a throw from his knees and loses the ability to generate force with the lower body. The injury is treated like most muscle strains, with a combination of rest, ice, anti-inflammatory medication and stretching, Leland said, though the timetable for a return can often be hazy.

Current Examples: Cliff Lee, Seattle Mariners; Yadier Molina, St. Louis Cardinals

Elbow Injuries

961ed1e2-8e05-11de-9fc2-001cc4c002e0preview-300While the above injuries are more likely for position players, the vast majority of baseball injuries occur in pitchers. In the game of baseball, no action is more unnatural and violent than the pitch, as depicted in high-speed pictures that capture a pitcher’s arm at a seemingly impossible backwards angle.

“It’s just so abnormal what pitchers are doing with their arm,” Leland said. “Despite the fact that they only do it once a week, it really, really beats them up.”

Most pitcher injuries are concentrated in the elbow or the shoulder due the extreme forces put on the ligaments and musculature of those joints. If the elbow is the culprit, chances are it’s the ulnar collateral ligament that is strained or torn – the injury fixed by probably the most famous sports procedure today, Tommy John Surgery. Invented in 1974 by Frank Jobe to restore the career of pitcher Tommy John, the surgery (properly known as a UCL reconstruction) takes a hamstring or forearm tendon from the patient – or a cadaver – and actually rebuilds the torn ligament. Since its development, hundreds, if not thousands, of pitchers and other baseball players have received the procedure, sometimes twice.

“We are a lot more proactive for UCL injuries now than we were 10 years ago,” Leland said. “If someone has an elbow injury, the first thing any orthopedic surgeon will do is examine their elbow to see if it’s the UCL.”

However, the frequency with which Tommy John Surgery appears in the news has given some people the misconception that it’s a necessary part of a young pitcher’s development. Leland said some sports medicine doctors have been approached by the parents of teenage pitchers asking about UCL reconstruction before an injury even occurs, something no ethical doctor would consider. It’s important to remember, Leland said, that despite incredible advances in the procedure producing an 80 percent success rate, that still means 1 out of every 5 pitchers who receive the surgery will never return to their previous ability.

“That’s pretty high,” Leland said. “In any one organization you’ll have 5 UCL reconstructions every 1 or 2 seasons, and one of those guys is never going to get back to pitching the same way again.”

Current Examples: Jordan Zimmermann, Washington Nationals; Joe Nathan, Minnesota Twins

Shoulder Injuries

The other common injury locus for pitchers is at the shoulder, which also experiences incredible strain from the unnatural motion of pitching. One sensitive structure is the labrum, a tendon that helps stabilize the ball-and-socket structure of the shoulder, acting as “a combination between a car bumper and a suction seal,” Leland said. The biceps tendon connects the labrum to the elbow, and with each pitch the biceps pulls down on the labrum. With enough damage, these mechanics can produce a SLAP tear: superior labrum anterior to posterior.

To a pitcher’s ears, “SLAP tear” can mean “season’s over.” Trainers will try to nurse the shoulder back to health with a standard recovery protocol: rest and anti-inflammatory medication, then a regimen of stretching and long-tossing. But if that program doesn’t restore a pitcher’s velocity and accuracy to normal or his pain persists, it’s time to schedule surgery. Unlike Tommy John Surgery, where surgeons must build a new UCL, a torn labrum can be repaired, but the timeline from successful surgery to pitching again is still typically 6 months, Leland said.

Labrum tears are not the only kind of shoulder injury that can interrupt a pitcher’s season. Leland and colleagues recently published a paper on a rarely-seen injury to a muscle called the teres major, located at the back of the shoulder. Two different pitchers complained of pain in the back of their shoulder after throwing an off-speed pitch, and an MRI revealed an injury to the teres major, not typically known as a muscle involved in overhand throwing. Neither pitcher required surgery, Leland said, but the injury was so rare that team doctors were unsure of the best recovery protocol – the reason for publishing the injuries in a medical journal.

Throwing an offspeed pitch, where a pitcher attempts to fool the batter by using the same wind-up to throw a much slower pitch, may have contributed to the injuries. Leland speculates that slowing down the pitch at the last possible moment may put extra strain on the teres major and other muscles of the posterior shoulder, a theory that further biomechanical work will have to test.

“The holding back might be what causes that type of injury, because you’ve still got to generate the forces, otherwise the batter will clearly see that you didn’t reach back as far so the ball is not coming as fast,” Leland said. “If you advertise it like that, the batter’s going to know what’s coming and they’ll hit it out of the park.”

But for youth pitchers often instructed not to throw curveballs and other offspeed pitches to protect their arms, Leland said there is a much more important precaution to prevent arm injury – pitch counts.

“It’s thought that curveballs destroy young kids’ elbows. But researchers are finding that while they do have increased likelihood of injury over a fastball, it’s really the number of pitches that are more important,” Leland said. “Unfortunately, it’s very, very difficult for youth baseball kids who may be on multiple teams. It falls down to parents to really make sure that despite all the leagues they’re on, they’re following an explicit limit on number of pitches thrown.”

Current Examples: Kelvim Escobar, New York Mets; Brandon Webb, Arizona Diamondbacks


Leland, J., Ciccotti, M., Cohen, S., Zoga, A., & Frederick, R. (2009). Teres major injuries in two professional baseball pitchers Journal of Shoulder and Elbow Surgery, 18 (6) DOI: 10.1016/j.jse.2009.01.025

About Rob Mitchum (525 Articles)
Rob Mitchum is communications manager at the Computation Institute, a joint initiative between The University of Chicago and Argonne National Laboratory.
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