Overhand throwing, such as in baseball, and repetitive overhead activities place extremely high stresses on the shoulder. Dr. Elizabeth M. Ignacio, Surgical Director at The Queen’s Center for Sports Medicine, explains the causes of the wide range of overuse injuries that can affect the “throwing athlete.”
Who is at risk for overhead shoulder injuries?
Elizabeth M. Ignacio, MD: Although overhead shoulder injuries most commonly occur in baseball pitchers, they are not the only “throwing athlete” that can be affected. These injuries can also be seen in any athlete who participates in sports that require repetitive overhand motions, such as volleyball, tennis, water polo, swimming, and some track and field events.
What causes overhead shoulder injuries?
Elizabeth M. Ignacio, MD: Shoulder injuries are caused by repetitive overhead activities, which place stresses specifically to the anatomy that keeps the shoulder stable.
When one structure — such as the ligament system — becomes weakened due to repetitive stresses, other structures must handle the overload. As a result, a wide range of shoulder injuries can occur in the throwing athlete.
The rotator cuff and labrum are the shoulder structures most vulnerable to throwing injuries.
Is there a specific movement that places more stress on the shoulder than others?
Elizabeth M. Ignacio, MD: Of the five phases that make up the pitching motion, the late cocking and follow-through phases place the greatest forces on the shoulder. Similar movements also occur in volleyball, swimming, and other activities.
Late-cocking phase: In order to generate maximum pitch speed, the thrower must bring the arm and hand up and behind the body during the late cocking phase. This arm position of extreme external rotation helps the thrower put speed on the ball, however, it also forces the head of the humerus (upper arm bone) forward, which places significant stress on the ligaments in the front of the shoulder. Over time, the ligaments loosen, resulting in greater external rotation and greater pitching speed, but less shoulder stability.
Follow-through phase: During acceleration, the arm rapidly rotates internally. Once the ball is released, follow-through begins and the ligaments and rotator cuff tendons at the back of the shoulder must handle significant stresses to decelerate the arm and control the humeral head (the head of the upper arm bone that fits into the rounded socket of your shoulder blade).
Left untreated, injuries in the shoulder can become complicated conditions. If you know an athlete who may be at risk for overhead shoulder injuries, The Queen’s Center for Sports Medicine provides comprehensive care for the treatment and prevention of sports injuries and conditions in athletes and active people of all ages. For more information, or to schedule an appointment, call 808-691-4449 or request an appointment online.
Source: Reproduced in part from the American Academy of Orthopedic Surgeons, OrthoInfo.org