Incidence of Postoperative Delirium in Patients Undergoing Total Knee Arthroplasty-an Asian Perspective

Background: Very little is known in the literature with regards to the incidence of postoperative delirium following total knee arthroplasty (TKA) in Asians and the associated surgical factors. We conducted a retrospective study on incidence of postoperative delirium following TKA in Asians.

Methods: One thousand sixteen knees of 954 consecutive patients who underwent TKA by the senior author of this study in the year 2006 were included in this review. All written and electronic medical records for patients were screened. Delirium was recorded to be present based on clinical entry onto the patients' inpatient hospital notes and a diagnosis made by psychiatrist based on the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV). All statistical analysis was performed using SPSS v.18.0 (IBM Corp., Armonk, NY, USA).

Results: The incidence of postoperative delirium in our patients undergoing TKA was 0.59%. Six patients had a confirmed diagnosis of delirium postoperatively. We noted an association between a higher mean age (P<0.0001), a lower body mass index (P<0.0001), Chinese ethnicity (P=0.002), male gender (P=0.002) and chronic opioid use (P<0.0001) with incidence of post-operative delirium. We also noted a higher proportion of post-operative DVT (P<0.0001) and wound infection (P<0.0001) in the delirium group.

Conclusions: The incidence of postoperative delirium in Asians undergoing TKA in our institution is very low at 0.59%. Advanced age, lower body mass index, Chinese ethnicity, male gender and preoperative chronic opioid use may be associated with developing postoperative delirium.