Patient optimization is becoming increasingly important before arthroplasty to ensure outcomes. It has been suggested that depression is a modifiable risk factor that should be corrected preoperatively. It remains to be determined whether psychological intervention before surgery will improve outcomes. We theorized that the use of preoperative depression scales to predict postoperative outcomes may be influenced by the pain and functional disability of arthritis. To determine whether depression is a modifiable risk factor that should be corrected preoperatively we asked the following questions: (1) What is the prevalence of depression in arthroplasty patients preoperatively? (2) Do depressive symptoms improve after surgery? (3) Is preoperative depression associated with outcome?