A growing number of elderly patients undergo total knee arthroplasty. Delirium is a common complication in these patients after surgery and is associated with worse outcomes, including prolonged hospital stay, poor functional recovery, decreased cognitive function, increased health care costs, and elevated mortality rate. Dexmedetomidine has been shown to prolong the duration of nerve block without neurotoxicity and improve postoperative sleep quality. The investigators hypothesize that dexmedetomidine, when combined with ropivacaine for continuous femoral nerve block, can reduce the incidence of delirium and improve the long-term outcome in elderly patients after total knee arthroplasty.
Delirium is common in the elderly after orthopedic surgery and is associated with worse outcomes. Continuous femoral nerve block is frequently used for postoperative analgesia after total knee arthoplasty. The investigators hypothesize that dexmedetomidine, when combined with ropivacaine for continuous femoral nerve block, can reduce the incidence of delirium and improve the long-term outcome in elderly patients after total knee arthroplasty.