The shoulder is a ball-and-socket joint formed by the humerus – the upper arm bone – and the glenoid fossa – part of the shoulder blade. This joint moves in many directions beyond simply forward with flexion and backward with extension. It also turns in toward the body with internal rotation, and away from the body with external rotation. With abduction, the shoulder moves out to the side, and in adduction, it moves in toward the side of the body. Several conditions cause impairment in shoulder range of motion.
Adhesive capsulitis – more commonly called “frozen shoulder” – is a common condition that significantly impairs shoulder range of motion. As soft tissue called the joint capsule begins to stick to the head of the humerus, range of motion progressively decreases, making everyday activities difficult. The cause of most cases of adhesive capsulitis is unknown; it appears to comes out of nowhere. According to American Family Physician, this condition affects 3 percent of the general population. It typically occurs between ages 40 to 70 and affects females more often than males. This condition eventually impairs range of motion in all directions.
Tendons attach shoulder muscles to the bones, producing movement of the joint. Tendon damage impairs shoulder range of motion. The rotator cuff muscles – supraspinatus, infraspinatus, teres minor and subscapularis – are the main movers of the shoulder joint. Impaired motion is specific to the tendon that is damaged. The supraspinatus, which abducts the shoulder, is the most commonly injured rotator cuff tendon. The infraspinatus and teres minor perform external rotation, while the subscapularis performs internal rotation.
Pain and Inflammation
Impaired range of motion is sometimes a result of pain and inflammation. Arthritis, overuse injuries and tendonitis cause inflammation and pain in the shoulder joint. As the arm is raised, tendons can be pinched between the humerus and the acromion — part of the shoulder blade that forms a “roof” over tendons that attach to the front of the shoulder. During normal movement, muscles stabilize the humerus to maintain space between this bone and the acromion. However, swelling from inflammation makes this space smaller, causing impingement of the tendons. Shoulder range of motion is limited to approximately 90 degrees of flexion and abduction. Rotation in either direction may also be limited by pain.
Several interventions are used to treat range of motion impairment in the shoulder. Oral anti-inflammatory medications are prescribed to decrease swelling and pain to improve motion. Cortisone injections are sometimes administered to reduce swelling in the shoulder joint. Physical therapy interventions are frequently prescribed to address range of motion impairments. Manual stretching techniques and active exercise are used to stretch tight structures and improve mobility. Surgical intervention is required for severely limited motion from adhesive capsulitis, and to repair damaged tendons. Physical therapy addresses range of motion impairment after surgery to restore functional abilities.