Postoperative Outcomes in Primary Total Knee Arthroplasty Patients With Preexisting Cognitive Impairment: A Systematic Review

Introduction: To evaluate the body of evidence on the predictive value of preoperative cognitive impairment on in-hospital, short-term, and midterm postoperative outcomes for elderly patients undergoing total knee arthroplasty (TKA). Significance: With an aging population, an increasing percentage of the U.S. patient population will be living with cognitive impairment. There is currently no systematic review that assesses postoperative outcomes of patients with mild cognitive impairment (MCI) or preexisting diagnosis of dementia while undergoing elective primary TKA. Results: A database search between January 1, 1997, and November 1, 2017 in EMBASE, MEDLINE, and PubMed was conducted to identify articles that compared postoperative outcomes after TKA between patients aged 60 years with and without cognitive impairment. Cognitive impairment included preexisting diagnosis of dementia or MCI identified during preoperative assessment. Eligible articles were selected using dual reviewer and third-party arbitrator. The quality of the studies was evaluated using the Newcastle-Ottawa Scale. The strength of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach. A total of 6163 abstracts were screened. Only 11 full text articles met inclusion criteria, including 1 case-control, 5 prospective cohort, and 5 retrospective cohort studies. Two studies were of poor quality. Overall, there is moderate strength of evidence for increased risk of postoperative delirium, increased length of stay, and discharge to health-care facility among patients with preoperative MCI or preexisting dementia. The body of evidence is weak for other outcomes of interest including mortality, functionality and complications while in-hospital and in the short- and midterm. Conclusion: This review highlights the need for additional good quality studies to provide more information about MCI and dementia as risk factors in primary TKA.