Three Variants of the PENG Block With and Without Perineural Adjuvants in Older Adults

Hip surgery in older adults is frequently associated with significant postoperative pain, delayed mobilization, and increased opioid requirements. Poor pain control in this population can lead to complications such as delirium, prolonged hospitalization, reduced physical function, and slower rehabilitation. Effective regional anesthesia may improve safety and recovery after hip surgery.

The Pericapsular Nerve Group (PENG) block is a relatively new regional anesthesia technique designed to target the sensory innervation of the hip joint while preserving motor function. This motor-sparing feature may allow earlier mobilization and reduce the negative effects of immobilization in older patients.

Ropivacaine is the standard local anesthetic commonly used in peripheral nerve blocks. Small doses of adjuvant medications such as dexamethasone or dexmedetomidine may prolong the duration of analgesia and improve the quality of pain control. However, it remains unclear whether the addition of these medications provides any clinically meaningful benefit when used with the PENG block in older adults. There is also limited evidence directly comparing different adjuvants to a standard PENG block without additional medication.

This randomized controlled trial will compare three variants of the PENG block in adults aged 65 years and older undergoing hip surgery. All participants will receive a PENG block with 20 mL of 0.2% ropivacaine. They will then be randomly assigned to one of three groups:

Standard PENG block with ropivacaine alone (no adjuvant). PENG block with 4 mg of perineural dexamethasone. PENG block with 25 micrograms of perineural dexmedetomidine. All patients will receive standard perioperative care and multimodal analgesia. The study will assess pain scores, time to first rescue analgesia, total opioid consumption, functional mobility, incidence of postoperative nausea and vomiting, block duration, motor function, and complications. Safety will also be monitored, including block-related and neurological adverse events.

The primary objective of this study is to determine whether perineural dexamethasone or dexmedetomidine improves postoperative analgesia compared with a standard PENG block without adjuvant. The investigators hypothesize that both adjuvants may prolong analgesia and reduce opioid requirements, but their effectiveness and safety profile may differ.

This study aims to provide evidence that can help guide anesthesiologists in selecting the optimal variant of the PENG block for older adults undergoing hip surgery, intending to improve postoperative pain control, support early rehabilitation, and reducing complications associated with opioid use and delayed mobilization.

Inclusion criteria

• Age 65 years or older
• Scheduled for elective or emergency hip surgery (e.g., hip fracture fixation or hip arthroplasty)
• ASA physical status I-III
• Planned use of a PENG block as part of perioperative analgesia
• Ability to communicate pain intensity using the NRS scale
• Written informed consent obtained from the patient or legal representative

Exclusion criteria

• Refusal or inability to provide informed consent
• Known allergy, intolerance, or contraindication to any of the study medications: ropivacaine, dexamethasone, dexmedetomidine
• Pre-existing neurological deficit or neuropathy in the affected limb
• Coagulopathy or laboratory abnormality that contraindicates regional anesthesia: INR >1.5, or platelet count <100,000/µL, or therapeutic anticoagulation that cannot be safely paused
• Infection at or near the needle insertion site
• Severe hepatic or renal impairment
• Chronic opioid therapy (>30 days of daily opioids before surgery)
• Cognitive impairment or delirium that prevents reliable pain assessment
• BMI >40 kg/m² (due to potential technical difficulty and reduced accuracy of ultrasound guidance)
• Previous regional block affecting the target area for the current surgery
• Pregnancy or breastfeeding
• Participation in another interventional clinical trial within 30 days