Effect of tourniquet technique on postoperative delirium in elderly patients with total knee arthroplasty: a randomized single-blind controlled trial

BACKGROUND: The tourniquet technique is often used in total knee arthroplasty (TKA). However, its effect on postoperative delirium (POD) in elderly patients undergoing TKA is unknown. METHODS: This prospective randomized controlled trial assessed the eligibility of 245 elderly patients. A total of 197 patients who met the inclusion criteria were randomly divided into a tourniquet group (n = 98) and a non-tourniquet group (n = 99). The primary outcome was the incidence of POD within 72 h after surgery. The secondary outcome was the quality of rehabilitation, including inflammatory reaction, postoperative pain, hypoproteinemia and anemia. RESULTS: Of 245 patients, 184 patients completed this clinical trial, with 92 cases in each group. There were 14 patients (15.22%) with POD in the tourniquet group and 5 patients (5.43%) in the non-tourniquet group (95% CI 1.076 to 9.067, P = 0.029). The changes in white blood cell count (WBC), the proportion of neutrophils (NEUT%), c-reactive protein (CRP), interleukin-6 (IL-6) and middle patellar circumference in the tourniquet group were higher than those in the non-tourniquet group (P < 0.05). The visual analog scale (VAS) at rest and activity in the tourniquet group were higher than those in the non-tourniquet group (F = 170.102, P < 0.001 F = 75.391, P < 0.001). There were 41 (44.57%) patients with hypoproteinemia in the tourniquet group and 26 (28.26%) in the non-tourniquet group (95% CI 1.106 to 3.765, P = 0.022). CONCLUSION: The application of the tourniquet technique in elderly patients with TKA procedures increased the incidence of POD. This may be attributed to the increased inflammatory reaction, severe postoperative pain and hypoproteinemia caused by the tourniquet technique. TRIAL REGISTRATION: Clinical trial registration number: ChiCTR2100045711. Full date of the first registration: 23/04/2021.