Longer-term outcomes such as functional and health-related quality-of-life (HRQoL) outcomes will also be recorded by the ODC total joint registry at 6 months, 1 year, 2 years and 5 years postoperatively. Knee function will be measured using the new Knee Society Knee Score (KSKS) and Function Score (KSFS)29. The KSKS and KSFS each range from 0 (worst) to 100 (best). In addition, the Oxford Knee Score (OKS)31 will also be used, which is a 12-item, patient-assessed questionnaire designed specifically for use in patients undergoing TKA. Each item is scored from 1 (least difficulty/severity) to 5 (most difficulty/severity), and individual item scores are summed to yield an overall score ranging from 12 (no pain or limitation) to 60 (severe pain or limitation). HRQoL will be assessed based on the 36-Item Short Form Health Survey (SF-36) to obtain a baseline score. It consists of 36 questions categorised into 8 domains (physical functioning, bodily pain, role limitations due to physical health problems, role limitations due to personal or emotional problems, emotional well-being, social functioning, energy/fatigue, and general health perceptions). Higher scores indicate better health status and quality of life. Days alive and out of hospital (DAOH) will also be determined for each patient at 1 month, 6 months and 12 months to assess overall impact of postoperative delirium on morbidity and mortality. DAOH will be calculated based on death date (if present) and duration of all subsequent hospitalisations until the follow-up date. This will be recorded as a percentage by dividing DAOH by total potential follow-up period, which is the time period between the operation and the respective dates of follow-up (1 month, 6 months and 12 months).