The aim of this study was to examine the effect of pericapsular nerve group (PENG) block, which is frequently applied for postoperative analgesia in total hip replacement surgeries performed under spinal anesthesia, on postoperative cognitive function in patients aged 65 years and older.

The main question of the study is as follows:

Can the analgesic effect of preoperative PENG block without causing motor block in total hip replacement surgeries performed under spinal anesthesia in patients aged 65 years and older reduce the incidence of postoperative cognitive dysfunction (POCD)?

Patients aged 65 years and older, with (American Society of Anesthesiologists) ASA physical status I, II and III, and scheduled for total hip arthroplasty surgery under spinal anesthesia will be included in the study. Patient characteristics (age, gender, body mass index, etc.), Confusion Assessment Method (CAM), Yesavage Geriatric Depression Scale, Frail Frailty and Mini-Mental State Examination (MMSE) performed face-to-face will be recorded. Preoperatively, 24-72 hours before, patients' cognitive functions will be re-evaluated out of 26 points with telephone versions of the MMSE (T-MMSE). Intraoperatively, surgical duration, dermatomal block level due to spinal anesthesia, ephedrine or atropine requirement, pulse and blood pressure values will be recorded during the surgery. One group will receive a single dose ipsilateral pericapsular nerve group (PENG) block (20 ml 0.25% plain bupivacaine) under ultrasound guidance before surgery. The other group will receive a sham block. Cognitive function of the patients will be evaluated with T-MMSE on the 1st, 7th, 30th and 90th days postoperatively. Postoperative pain status of the patients will be recorded face-to-face at 0, 2, 8, 16, 24 and 48 hours, and via telephone on the 7th, 30th and 90th days with numerical rating scale (NRS).

Inclusion Criteria:

• Patients who will undergo surgery with spinal anesthesia due to total hip replacement
• ASA (American Society of Anesthesiologists) I-II-III patients
• Patients aged 65 and over
• Patients with a preoperative fasting period of approximately 8 hours

Exclusion Criteria:

• Refusal to participate in the study
• ASA (American Society of Anesthesiologists) score of 4 and above
• Body mass index >40 kg/m²)
• Failure of spinal block
• Patients who underwent surgery with general anesthesia
• Patients who received preoperative and intraoperative sedation
• Patients who will undergo revision surgery
• Patients with a history of drug use
• Patients with psychiatric disorders or those taking antipsychotic medications (depression, bipolar disorder, schizophrenia, etc.)
• Patients with central nervous system disease (Alzheimer's disease, Parkinson's disease, multiple sclerosis, etc.)
• Patients who do not accept spinal anesthesia and/or pericapsular nerve group (PENG) block
• Patients with a preoperative Mini Mental Test (MMT) score below 25
• Patients with contraindications for regional anesthesia techniques
• Patients who developed perioperative delirium
• Patients with visual or hearing impairment
• Patients who require blood or blood product transfusion during surgery
• Patients who cannot cooperate in the postoperative period