Comparison of Spinal Anesthesia With Intrathecal Morphine Versus PENG Block With or Without Dexamethasone in Hip Arthroplasty

Postoperative pain after total hip arthroplasty is associated with increased opioid use, delayed mobilization, and a higher risk of adverse events, particularly in older adults. Spinal anesthesia with intrathecal morphine is widely used to improve postoperative analgesia; however, it may be associated with opioid-related side effects such as nausea, pruritus, urinary retention, and respiratory depression. Ultrasound-guided regional nerve blocks, including the pericapsular nerve group (PENG) block, have emerged as opioid-sparing alternatives that may provide effective analgesia while preserving motor function.

This prospective, randomized, multicenter clinical trial is designed to compare the efficacy and safety of three regional anesthesia strategies in patients undergoing elective total hip arthroplasty. Participants aged 60 years and older will be randomly assigned in a 1:1:1 ratio to one of three study groups: spinal anesthesia with intrathecal morphine; spinal anesthesia combined with a PENG block; or spinal anesthesia combined with a PENG block using perineural dexamethasone as an adjuvant.

All participants will receive standardized spinal anesthesia with ropivacaine. In the control group, intrathecal morphine will be administered as part of routine spinal anesthesia. In the intervention groups, the PENG block will be performed under ultrasound guidance using ropivacaine, with or without the addition of dexamethasone. Perioperative care, postoperative analgesic protocols, and rehabilitation pathways will be standardized across all study centers to minimize variability.

Pain intensity at rest and during movement will be assessed using a visual analog scale at predefined time points within the first 48 hours after surgery. Secondary outcomes include total opioid consumption, time to first rescue analgesia, early mobilization, length of hospital stay, incidence of opioid-related and block-related adverse events, and changes in inflammatory markers measured in peripheral blood.

The results of this study will provide comparative evidence on opioid-based versus opioid-sparing regional anesthesia strategies for hip arthroplasty and may help inform clinical decision-making aimed at improving postoperative pain control, functional recovery, and safety in older surgical patients.

• Intrathecal Morphine (Drug), also known as Morphine (intrathecal): Intrathecal morphine administered as part of spinal anesthesia for postoperative pain control during elective total hip arthroplasty.
• Pericapsular Nerve Group Block (Procedure), also known as PENG Block: Ultrasound-guided pericapsular nerve group block performed as an adjunct to spinal anesthesia to provide postoperative analgesia.
• Dexamethasone (Drug), also known as Dexamethasone (perineural): Perineural dexamethasone administered as an adjuvant to the pericapsular nerve group block to prolong postoperative analgesia.

Primary outcomes

• Total Postoperative Opioid Consumption [Up to 48 hours after surgery]: Total amount of opioids administered postoperatively, expressed as intravenous morphine equivalents.

Secondary outcomes

• Pain scores at rest [6 hours after surgery]: Numeric Rating Scale (NRS), ranging from 0 ("no pain") to 10 ("the worst pain imaginable")- at rest and during mobilization
• Pain scores durring movement [6 hours after surgery]: Numeric Rating Scale (NRS), ranging from 0 ("no pain") to 10 ("the worst pain imaginable")- at rest and during mobilization
• Pain scores at rest [12 hours after surgery]: Numeric Rating Scale (NRS), ranging from 0 ("no pain") to 10 ("the worst pain imaginable")- at rest and during mobilization
• Pain scores durring movement [12 hours after surgery]: Numeric Rating Scale (NRS), ranging from 0 ("no pain") to 10 ("the worst pain imaginable")- at rest and during mobilization
• Pain scores at rest [24 hours after surgery]: Numeric Rating Scale (NRS), ranging from 0 ("no pain") to 10 ("the worst pain imaginable")- at rest and during mobilization
• Pain scores durring movement [24 hours after surgery]: Numeric Rating Scale (NRS), ranging from 0 ("no pain") to 10 ("the worst pain imaginable")- at rest and during mobilization
• Pain scores at rest [48 hours after surgery]: Numeric Rating Scale (NRS), ranging from 0 ("no pain") to 10 ("the worst pain imaginable")- at rest and during mobilization
• Pain scores durring movement [48 hours after surgery]: Numeric Rating Scale (NRS), ranging from 0 ("no pain") to 10 ("the worst pain imaginable")- at rest and during mobilization
• Time to First Rescue Analgesia [Up to 48 hours after surgery.]: Time from the end of surgery to the first request for rescue analgesic medication.
• Early Mobilization [Up to 48 hours after surgery]: Time to first mobilization assessed using the Timed Up and Go test.
• Incidence of Opioid-Related Adverse Events [Up to 48 hours after surgery.]: Occurrence of opioid-related adverse events, including nausea, vomiting, pruritus, and urinary retention.
• Length of Hospital Stay [measured at the day of the discharge from the hospital]: Total duration of postoperative hospitalization measured in days.

Sex: All, ages: 60 Years to 100 Years

Inclusion Criteria:

* Adults aged 60 to 100 years
* Scheduled for elective total hip arthroplasty
* American Society of Anesthesiologists (ASA) physical status I-III
* Ability to understand the study procedures and provide written informed consent

Exclusion Criteria:

* Known allergy or hypersensitivity to ropivacaine, morphine, or dexamethasone
* Coagulation disorders or ongoing anticoagulant therapy contraindicating spinal anesthesia or regional nerve blocks
* Infection at the site of spinal or peripheral nerve block injection
* Pre-existing neurological disorders affecting sensory or motor function
* Severe hepatic or renal insufficiency
* Chronic opioid use for more than 3 months prior to surgery
* Refusal or inability to provide informed consent

• Malgorzata Reysner, MD PhD, Study chair, Poznań University of Medical Sciences