The systematic literature review, Comparative Effectiveness of Nonoperative and Operative Treatments for Rotator Cuff Tears, was conducted in 2010 to examine the effectiveness of various nonoperative and operative treatments for adults with partial- or full-thickness rotator cuff tears. The review addressed six Key Questions (KQs) that compared patient outcomes after various operative approaches and techniques, early versus late surgical repair, operative versus nonoperative treatment and between various nonoperative therapies. The outcomes included health-related quality of life, return to work, pain, shoulder function, rotator cuff integrity, and complications. However, adverse treatment effects and the impact of baseline patient and injury characteristics on outcomes were also included. The systematic review was unable to fully answer the KQs using the rotator cuff literature from 1990 through August 2009 because the literature was sparse and of low to moderate quality. Of the 137 studies included, less than one-fifth were clinical trials and more than half were uncontrolled studies. The literature limitations included low study quality, disparate treatments and outcomes, small sample sizes, incomplete followup, and a heavy focus on surgical technique or approach research over other aspects of rotator cuff treatment (82 percent of studies). The randomized clinical trial (RCT) literature was of particularly low quality with high risk of bias from the manner in which the studies had been conducted. The observational study literature was of moderate quality but often lacked control for the effects of potential confounding factors on outcomes. For most rotator cuff interventions, only sparse data were available, which precluded firm conclusions about the value of any single approach in the optimal management of rotator cuff tears. Although most interventions showed positive effects, few improvements were of clinical importance. The paucity of evidence on early versus delayed surgery (one trial) was a noted concern because of the lack of evidence available for providers and patients on the important choice of initial nonoperative management or immediate surgical repair. The review concluded that more research and higher quality research are needed to determine the relative effectiveness of rotator cuff treatments. This Future Research Needs follow-on project used stakeholder feedback to identify and prioritize the current research knowledge gaps in rotator cuff treatment in order to improve outcomes after rotator cuff tears. The focus of this project was on treatment and post-treatment outcomes rather than complications, because the systematic review found that rotator cuff treatment complications were infrequent and often not clinically important.