Transient cognitive changes after surgery may be due to many different factors. It is estimated that between 5-29% of patients undergoing orthopedic surgery experience a transient decline in their cognition. Fat and bone marrow debris embolization can cause cognitive changes if they enter the cerebral circulation in significant numbers. During total hip arthroplasty the placement of the femoral stem leads to a rise in intramedullary pressure which can cause fat and bone marrow debris to embolize into the systemic circulation. Total hip resurfacing arthroplasty avoids entrance into the femoral canal. The purpose of this study is to assess transient cognitive changes after total hip arthroplasty and compare them to patients undergoing total hip resurfacing arthroplasty. We hypothesize that patients undergoing total hip resurfacing arthroplasty will experience less transient cognitive changes due to the avoidance of violating the femoral canal during the procedure.