This study investigated upon the different risk factors that may be involved in delirium formation after total knee arthroplasty in the geriatric population.

A retrospective analysis of 170 patients who had unilateral or bilateral total knee arthroplasty was done. Knee osteoarthritis, rheumatoid arthritis, spontaneous osteonecrosis of the knee, and psoriatic arthritis was diagnosed at surgery. Gender, age, presence of comorbidities, sedative usage, peri-operative loss of blood, pre- and post-operative laboratory blood test outcomes were examined.

After the surgery, delirium was found in 11 patients out of total 170 patients (6.5%) with a mean age of 79.5 (± 6.9) years. The delirium group had higher age, sedative-hypnotics usage; low values of pre-operative Hb and Ht, low values of post-operative Hb, Ht and BUN. According to the multivariate logistic regression analysis, sedative usage and Hb level prior to the operation were found to be independent risk factors for occurrence of delirium after total knee arthroplasty (TKA). As per the receiver operating characteristic curve analysis, Hb value of <11.1 g/dL before the surgery was a predictor for the growth of delirium.

Delirium was found in elderly patients who had pre-operative Hb level (< 11.1 g/dL) or who used sedative-hypnotics after TKA. In such patients, the post-operative delirium risk can be reduced by peri-operative management and undertaking preventative measures.