Modern studies have evaluated the risk factors and incidence of postoperative delirium in post-TJA patients. In current literature, incidence ranges from 0-10%. However, the epidemiology of these studies mainly focused on non-Asian populations. The investigators hope to determine both the incidence and risk factors of postoperative delirium in patients undergoing TJA with a focus on the Asian population. This is especially relevant in today's ageing Asian population.