The purpose of this study is to further understand the effect pain has by measuring constant shoulder scores in patients before and after ultrasound guided subacromial (the outer end of the shoulder blade) injection of lidocaine (a local anesthetic or numbing agent) compared to saline (salt solution), in patients indicated for arthroscopic rotator cuff repair. The saline and lidocaine has been approved for use by the U.S. Food and Drug Administration (FDA). The constant shoulder score includes your level of pain, activity level, range of motion and strength measures.