The critical shoulder angle and its correlation with rotator cuff tears and alternatively glenohumeral osteoarthritis has become a popular research topic in recent years. With carefully standardized x-rays, a correlation emerges. This development has generated interest in potential clinical usefulness for this measurement, as well as possible surgical interventions to modify the course of these shoulder problems. Lateral acromioplasty may have a role in rotator cuff surgery, but early study results are mixed. Prophylactic lateral acromioplasty has been proposed but would not be evidence based at this time, and there could be unintended negative consequences. For now, accurate x-ray films and awareness of the critical shoulder angle by the clinician could impact the index of suspicion and also may prove useful in patient counseling for these 2 shoulder diseases.