Shoulder tendinitis is a common overuse injury in sports (such as swimming, baseball and tennis) where the arm is used in an overhead motion. The pain – usually felt at the tip of the shoulder and referred or radiated down the arm – occurs when the arm is lifted overhead or twisted. In extreme cases, pain will be present all of the time and it may even wake you from a deep sleep.
The shoulder is a closely fitted joint. The humerus (upper arm bone), the tendons of the rotator cuff that connect to the muscles that lift the arm, and associated bursa (friction reducing membranes), move back and forth through a very tight archway of bone and ligament called the coracoacromial arch. When the arm is raised, the archway becomes smaller and compresses the tendons and bursa. Repetitive use of the arm makes the tendons and bursa prone to injury and inflammation.
Bursitis occurs when the bursa becomes inflamed and painful due to compression inside of the coracoacromial arch.
Tendinitis occurs when a rotator cuff tendon becomes inflamed, swollen and tender. Symptoms of tendinitis and bursitis usually last for only a few days, but may recur or become chronic.
Stages of tendinitis
• Overuse tendinitis. Shoulder motions used during activities like golfing, throwing or overhead lifting may cause repetitive stress within the rotator cuff, leading to irritation, bruising or fraying of the tendon. This can cause shoulder pain and weakness in the joint.
• Calcific tendinitis. Inflammation over a long period of time can sometimes result in a build-up of calcium deposits within the rotator cuff tendons. This leads to pain and loss of shoulder strength and motion.
• Impingement tendinitis. When the space is narrowed between the rotator cuff and the coracoacromial arch, the humerus can “pinch” the rotator cuff tendon into the arch. This can happen when the cuff is weak, the bursa is swollen or if there is a bone spur present. Tendinitis caused by impingement can occur with repetitive shoulder activities, such as sports or jobs involving overhead reaching.
• Rotator cuff tear. Severe tendinitis from long term impingement, degeneration, or sudden injuries like falling can cause partial or complete tearing of the rotator cuff tendon(s). This can result in more severe shoulder pain, weakness and loss of normal movement and function.
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