The Shoulder and Elbow Service at Washington University has had extensive experience in studying various factors related to not only the progression of rotator cuff disease, but also tendon healing and outcomes of treatment 8, 14-16. A strength of our research team has been the collaborative experience developed with musculoskeletal radiologists at the Mallinkrodt Institute using high-resolution ultrasound to examine the integrity of the rotator cuff. Extensive data with ultrasound at this institution has validated it as a highly accurate means of identifying and quantifying rotator cuff tears in both the preoperative and postoperative settings 17-20. High-resolution ultrasound, in the hands of experienced musculoskeletal radiologists, has been proven to be more accurate than magnetic resonance imaging in assessing the integrity of the rotator cuff in the postoperative setting 19. With this modality, we have been able to study the outcomes and tendon healing rates following repair of the rotator cuff using conventional arthroscopic repair techniques 8. Recent data, from this institution, has also been completed examining the clinical outcomes and repair integrity following newer arthroscopic techniques (double-row rotator cuff repairs) in three separate patient populations: partial thickness cuff tears, full thickness cuff tears and revision of recurrent rotator cuff tears (manuscripts in progress). Our service has also been currently involved in a NIH R01 funded study prospectively examining factors related to the progression of asymptomatic rotator cuff tears over time. Given our research experience with ultrasound, the Shoulder and Elbow Service at Washington University has been uniquely positioned to study one of the most important issues in shoulder surgery - the effect of rehabilitation on healing of the rotator cuff following surgical repair.