Shoulder Impingement & Tendonitis

Injury Description

This is one of the most commonly occurring injuries in sports where the arm is used in an overhead motion (i.e. swimming, baseball). The pain is usually felt on the tip of the shoulder or part way down the shoulder muscle. The pain is felt when the arm is lifted overhead or twisted in a certain direction. In extreme cases, pain will be present all the time and it may even wake the injured individual from a deep sleep. Throwing a baseball overhand or working overhead may become impossible.



The tendons of the muscles that life the arm, and the associated bursa (fluid filled sac that prevents friction) go through a very tight channel of bone (see diagram). When the arm is raised, the channel becomes smaller and makes the area very prone to inflammation. When the arm is used overhead, it can bring the asymetric bony prominence of the humerus to pinch or "impinge" against the roof of the shoulder joint. This pinches the rotator cuff and leads to tendonitis. If left too long, it can actually tear the rotator cuff.

Predisposing Factors

  • Overuse: This is the most common cause of the problem and the result of repetitive overhead motions.
  • Weak muscles: When the muscles are weak more force is exerted on the tendons and bursea causing inflammation and pain (tendonitis, bursitis).
  • Improper or inappropriate swimming or throwing techniques.
  • Strenuous training: One hard throw may start the problem.
  • Previous injuries to the shoulder.
  • Loose shoulder joint.
  • Calcium deposits.
  • Impingement of osteophytes (bone spurs) on the shoulder joint causing impingement