Shoulder Injuries in Overhead Athletes

Abstract

Shoulder symptoms in overhead athletes are related mainly to failure of the kinetic chain—specifically at the hip joint, trunk, and scapula—as well as to anatomical failure at the shoulder joint. Once the kinetic chain fails, the shoulder biomechanics can change, resulting in overstress in specific soft tissues, including tendons, ligaments, and muscles, or at the joint surface (cartilage or subchondral bone), along with reduced throwing performance. In the early stage of the pathologic kinetic chain, shoulder pain is generated without anatomical failure in the shoulder joint. Most early-stage symptoms can be effectively treated non-operatively. When the pathologic kinematic chain (including scapular dyskinesis, muscle imbalance, posterior tightness, and increased anterior laxity) is ameliorated with physical therapy, shoulder or elbow pain during throwing decreases or disappears in most cases. An understanding of the interactions in the upper-extremity kinetic chain, together with determination of the precise pathologic condition in each athlete, is necessary for successful physical therapy. Moreover, the function of the trunk and lower extremity should be evaluated very carefully and then treated. If the pathologic kinetic chain is not appropriately treated in the early stage, soft tissue or cartilage in the shoulder may fail, leading to the advanced stage. In the advanced stage, anatomical failure should be evaluated with imaging studies, such as X-ray, CT, MRI, and ultrasonography, and it sometimes needs surgical treatment. The best surgical option needs to be determined on the basis of the patient’s background (gender, age, sport, and occupation) and the results of physical examination, including of shoulder laxity and stiffness.