The primary outcome will be the presence of postoperative delirium following TJA. Each patient will be assessed for delirium on postoperative day (POD) 1, 2 and 3 in the wards at 7am as well as the day of discharge. Delirium will not be evaluated on POD 0 due to difficulty in differentiating delirium from the effects of residual anaesthesia. The Confusion Assessment Method (CAM) will be used to detect postoperative delirium and delirium severity. Delirium is said to be present if the patient meets the CAM criteria for any of the postoperative assessments. Patients assessed to have delirium will be referred to the psychiatrists for further management.