Repetitive, powerful overhead motions in sports like baseball, tennis and volleyball can lead to a host of abnormalities and injuries to the shoulder that have characteristic appearances on MRI, according to a leading expert in sports imaging who spoke Wednesday.
As part of a day-long RSNA/European Society of Radiology (ESR) Sports Imaging Symposium, Lynne S. Steinbach, MD, professor emeritus of clinical radiology and orthopedic surgery at the University of California, San Francisco, discussed some of the scenarios that radiologists may face when studying images of the shoulders of athletes.
Dr. Steinbach focused her talk on baseball pitchers. The late cocking, acceleration and deceleration phases of throwing expose the shoulder to significant stress, she said.
"More than half of pitchers have shoulder injuries every year, usually from overuse," Dr. Steinbach said. "The areas most often affected include the labrum, the rotator cuff, biceps, ligaments and the capsule."
Dr. Steinbach played a video clip of Tim Lincecum, a former Major League Baseball All Star, showing how pitchers develop an extended range of motion that helps them generate more velocity on the baseball. This external rotation exceeds physiological limits, leading to adaptations like tears in the rotator cuff and bone changes that eventually cause physiological problems.
"With this repeated, very forceful motion, you can get impingement of the tendons and labrum between the bones, which can wear on the undersurface to the tendons and tear up the labrum and the biceps," Dr. Steinbach said. "The follow-through on the ball can thicken the capsule in the back of the shoulder and change the alignment of the shoulder."
The result is a veritable laundry list of injuries — posterior superior glenoid impingement, superior labral from anterior to posterior (SLAP) tears and osseous stress injuries, among others — that can be picked up on MRI.
"These injuries have different names, but the main thing for radiologists is to just describe what you're seeing," she said.
Injuries in Young Athletes
During the interactive portion of the session, Dr. Steinbach presented cases related to the growing problem of throwing-related injuries in young athletes.
"We're seeing 12-year-olds with rotator cuff tears from playing all year long," she said. "There's even a condition called Little League Shoulder that develops when overuse causes stress to the growth plates in the shoulder. The bones remodel, and eventually this remodeling changes how the shoulder fits together."
Audience members were asked to weigh in on several cases, including some involving abnormalities related to the apophyses, bony outgrowths that typically fuse with the bone by age 15 and serve as a site for tendon and ligament attachment. Radiologists should be aware of this problem, Dr. Steinbach said, and look for signs such as widening and high signal on T2-weighted sequences.
Other sessions in the RSNA/ESR Sports Imaging Symposium focused on lower extremity sports injuries, musculoskeletal interactive procedures and postoperative imaging of sports injuries.