The document discusses the rotator cuff, which is made up of four muscles and tendons that hold the humerus in the shoulder joint. Rotator cuff tears are a common cause of shoulder pain and disability. Tears can be classified based on timing (acute or chronic) and depth (partial or complete). Treatment for acute tears is usually surgical repair, while chronic tears may be treated with rest, physical therapy, and surgery if conservative treatment fails. Rehabilitation after repair focuses on protecting the repair while regaining range of motion and strength over 3 phases lasting 3-6 months.