Baseball shoulder injuries occur most often among pitchers, who may use greater throwing force or greater repetition than players in other positions. The overhead motion of pitching creates stress on the rotator cuff. A baseball injury can occur among any of the local joints, bones, cartilage, muscles, tendons and ligaments, and several parts may be damaged at once. According to the National Institutes of Health, children and adolescents and athletes older than 40 are most vulnerable to overuse injuries.
Muscle Strains
Placing unusual force on a muscle, as in a long or rapid throw, can cause a baseball injury known as a pulled or strained muscle. The tendon that attaches the muscle to a rotator cuff bone will also undergo stress. These shoulder injuries often occur after a hiatus in training. University Sports Medicine reports that the best way to avoid painful muscle strains is to warm up properly before practice or play.
Tendinitis/Bursitis
Repeated muscle and tendon strains can result in tendinitis, which results in severe shoulder pain and weakness, especially when the rotator cuff is in motion. University of Maryland Medical Center notes that the shoulder bursa, a cushioning tissue, can be aggravated by the same overhead throwing action. When the bursa becomes inflamed, the condition is called bursitis. Pain will be localized just beneath the joint capsule.
Joint Sprains
Shoulder injuries involving the acromioclavicular (AC) joint are called sprains. Ligaments stretch or tear, resulting in a separated shoulder. This baseball injury may occur following a bout of shoulder tendinitis or bursitis, when the rotator cuff is already weakened. It is characterized by immediate, severe pain and inability to move the shoulder.
As the American Orthopaedic Society for Sports Medicine (AOSSM) reports, the damage to ligaments may be mild or severe. The most minor AC joint sprain will leave the bone and surrounding tissue intact. A major sprain, however, will cause complete joint from bone separation, and may damage the adjacent cartilage and nerves, requiring surgical repair.
Stress Fractures
Shoulder injuries caused by repetitive motion and stress can result in bone fractures that develop gradually. Weakened muscles and connective tissue are less able to absorb shock, such as the snap action used in pitching. When the humerus takes a beating, it gradually gives way.
A stress fracture can be a difficult baseball injury to diagnose. The AOSSM notes that X-rays of the painful area may not reveal microcracks in the bone. A bone scan or magnetic resonance imaging (MRI) may be necessary to locate the stress fracture.
