Contains checklist and all the supporting tables.

<div><p>Background</p><p>There is a significant gap in research exploring changes in postoperative health-related quality of life (HRQoL) among patients aged 65 years and older undergoing hip or knee arthroplasty.</p><p>Objectives</p><p>To investigate the variations in HRQoL improvement, as evaluated by patient-reported outcome measures following total hip arthroplasty, total knee arthroplasty, and partial knee arthroplasty between the young-old and old-old adults.</p><p>Methods/Design</p><p>We searched six online databases (including MEDLINE, Embase) from their inception dates to May 15, 2023. We included studies using a validated HRQoL assessment tool to evaluate changes in HRQoL in patients aged ≥65 years undergoing hip or knee arthroplasty. These include the EuroQol five-dimension (EQ-5D), Short Form 36 (SF-36) and Short Form 12 (SF-12). The primary outcomes were postoperative HRQoL changes between young-old (65–74 years) and old-old groups (≥75 years). The secondary outcomes included complications, length of stay, and mortality.</p><p>Results</p><p>The search yielded 12,229 articles; twelve studies (n = 103,613) were included. Studies using EQ-5D found no significant differences between young-old and old-old patients after hip and knee arthroplasty. Analyses of SF-36 and SF-12 scales showed no significant age-related differences in postoperative improvements in physical and mental health. Our review of four studies that included multivariable analyses revealed inconsistent associations between age and EQ-5D. Comparisons between the young-old and old-old age groups in postoperative complications, hospital length of stay, and mortality revealed no associated age-related changes in HRQoL.</p><p>Conclusions</p><p>The young-old and old-old patients exhibited comparable improvement in HRQoL following hip or knee arthroplasty. The older patients did not have higher postoperative complications rates, longer hospital length of stay, and increased mortality. While chronological age should be considered when planning hip and knee arthroplasty, greater emphasis should be placed on assessing the comorbidities and functional status of patients.</p></div>