Before the operation, each patient will be interviewed to assess their baseline cognitive status. The Mini-Mental State Examination (MMSE) will be used, which is a 11-question screening tool used to evaluate the cognitive aspects of mental function. A score of 0-30 can be obtained with higher values denoting better cognitive function. A score of <24 suggests cognitive impairment. A MMSE test modified for use in Singapore will be use, due to cultural and climate differences. In addition, the test will be administered in English, Chinese or Malay, according to the language the participant is most well-versed in. The Chinese and Malay versions of MMSE have similar test questions and are scored the same way as the English version. Sensory impairment will be assessed during the preoperative interviews. Patients will be asked to wear their visual or hearing aids during these interviews. A patient will be considered to have visual or hearing impairment if the research member conducting the interview is unable to perform the interview normally due to the sensory impairment, such as raising his/her voice for a patient with impaired hearing. The grip strength of each patient will also be measured using the JAMAR® Plus+ Digital Hand Dynamometer (Sammons Preston Inc, Bolingbrook, IL). The patient baseline characteristics will be obtained from the medical records. Perioperative data is available through the Preoperative Evaluation Clinic (PEC) database as well as the Orthopaedic Diagnostic Centre (ODC) total joint registry, which will be prospectively entered into the REDCap™ database. This will include data regarding patient's demographics, smoking history, alcohol history, pre-existing medical conditions, preoperative medications. Each patient will also be rated preoperatively by an anaesthesiologist in the PEC based on the American Society of Anaesthesiologists (ASA) physical status classification. For analysis, the investigators will be calculating each patient's perioperative risk based on the Charlson Comorbidity Index (CCI). Preoperative laboratory results, including data about haemoglobin or creatinine level, will also be collected.