Abstract: Objective To investigate the application effect of ultrasound-guided pericapsular nerve group (PENG) block in elderly patients undergoing total knee arthroplasty (TKA). 
Methods A total of 120 patients with TKA who were treated in our hospital and the Affiliated Hospital of Nantong University were selected and divided into the observation group (n=60) and the control group (n=60) by envelope method. The observation group was given ultrasound-guided PENG block and general anesthesia, and the control group was given general anesthesia, to observe the anesthesia effects of the two groups. 
Results There was no significant difference between the observation group and the control group with respect to duration of operation, intraoperative bleeding and anesthesia time (P＞0.05). There was a significant difference in the interaction between time points and time points between groups in terms of mean arterial pressure (MAP), systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) between the two groups (P＜0.05), while there was no significant difference between groups (P＞0.05). There was no significant difference in interaction between groups, time points and time points between groups with respect to blood oxygen saturation (SpO2) (P＞0.05). There was a significant difference in interaction between groups, time points and time points between groups in terms of visual analogue scale (VAS) score for pain and comfort. 
Conclusion Ultrasound-guided PENG block has a good application effect in elderly TKA, with the advantages of less postoperative pain, and good comfort. 

Key words: arthroplasty, replacement, knee, ultrasound guidance, elderly