Postoperative Cognitive Dysfunction in Indian Patients Undergoing Total Knee Replacement Under Spinal Anesthesia

Total knee replacement is a common surgical procedure in the elderly. The number of surgeries has increased owing to the increasing life expectancy of the population and better functional outcomes postsurgery. Postoperative cognitive dysfunction (POCD) is an identified entity postsurgery in elderly but most of the studies have been on patients undergoing cardiac and other nonorthopaedic surgeries. The studies have shown variable incidence due to selection bias. We studied the incidence and probable predictive factors of POCD in elderly Indian population undergoing total knee replacement under spinal anesthesia.

We designed a prospective, observational study at a single center including patients above 60 years of age undergoing total knee replacement under spinal anesthesia. Preoperative mini-mental scale examination, electrolytes, urea and creatinine levels were recorded. Postoperatively, mini mental scale evaluation (MMSE) was done 2 days postsurgery, at 3 months, 6 months, and 1 year follow-up. Laboratory values postoperatively were recorded.

The average preoperative MMSE was 27 and declined to 25.4 on second postoperative day the value increased to 25.9, 26.6, and 27 at 3 months, 6 months, and 1-year follow-up, respectively. Sixty-three out of 600 patients developed POCD at second postoperative day. Forty-three patients showed recovery in subsequent visits and 20 patients had persistent dysfunction at the end of 1 year. Electrolyte imbalance, oxygen saturation, and age over 80 years were factors that showed statistically significant difference in multiple comparison analysis.

In our study, we have found POCD to be a definitive entity which can cause short- and long-term cognitive defect in elderly Indian population undergoing total knee replacement and electrolyte imbalance, age, and oxygen saturation were the significant factors in the patients who developed POCD.