Iliopsoas (IPB) and Pericapsular Nerve Group (PENG) Blocks Comparison on Analgesia and Recovery After Total Hip Arthroplasty

Comparison Between Iliopsoas Block (IPB) and Pericapsular Nerve Group (PENG) Block on Postoperative Analgesia and Functional Recovery After Total Hip Arthroplasty Surgery: a Double-blinded Randomized Clinical Trial

Background:

In recent years, regional anesthesia has become more popular because it can reduce pain and the need for strong pain medications like morphine. For hip surgery, the PENG block is already known to be effective. A newer method, called the iliopsoas plane block (IPB), is very similar and has also shown good results in hip arthroscopy. However, these two techniques have never been directly compared in patients undergoing hip replacement surgery using the posterior approach.

Goal:

This study aims to see if the IPB is just as effective as the PENG block for controlling pain and helping patients recover well after hip replacement surgery.

Method:

118 adult patients scheduled for hip replacement under spinal anesthesia will be randomly assigned to receive either: IPB: 7 ml of Ropivacaine 7.5 mg/ml PENG: 14 ml of Ropivacaine 3.75 mg/ml Both injections are given under ultrasound guidance 30 minutes before spinal anesthesia. Neither the patient, the surgeon, nor the data collector will know which technique was used.

Post-Surgery Care:

All patients will receive standard pain relief, including:

Paracetamol every 6 hours Etoricoxib once a day Morphine via a patient-controlled pump for 48 hours

Main Outcome Measured:

The primary goal is to compare pain during movement 6 hours after surgery, using a pain scale from 0 (no pain) to 10 (worst pain). The study will consider the two blocks equivalent if the difference in average pain scores is less than 1 point.

Other Outcomes:

Total morphine used in 48 hours Pain scores at rest and during movement at various time points Walking ability (2- and 6-minute walk tests, and timed-up-and-go test) Quality of recovery (using the QoR-15 questionnaire) Side effects of morphine Patient satisfaction Length of hospital stay

Safety:

Both techniques are safe and already used in clinical practice. Ultrasound guidance minimizes risks like nerve injury, bleeding, or infection.

Conclusion:

If the IPB is shown to be as effective as the PENG block, both can be considered reliable options for pain control and early recovery after hip replacement surgery.

Study Overview

• Status: Recruiting
• Conditions: Postoperative Pain Management; PENG Block; Peripheral Nerve Blocks; Total Hip Arthroplasty (THA); Iliopsoas Nerve Block
• Intervention / Treatment: Procedure: PENG Block; Procedure: Iliopsoas nerve block

Detailed Description

This study investigates the comparative effectiveness of two regional anesthesia techniques-the Pericapsular Nerve Group (PENG) block and the Iliopsoas Plane Block (IPB)-in patients undergoing total hip arthroplasty (THA) via the posterior surgical approach. While both blocks have shown promise in managing postoperative pain and minimizing opioid use, direct comparisons between them in this surgical context are lacking.

The PENG block, which targets the articular branches of the femoral, obturator, and accessory obturator nerves, has become increasingly used in anterior and lateral hip surgeries. The IPB, though more recently introduced, involves injection in a similar anatomical region and has shown good analgesic results in patients undergoing hip arthroscopy. Given their overlapping targets, these two blocks may offer comparable clinical benefits; however, this has not been validated in THA performed through a posterior approach.

To address this gap, the current randomized, double-blind equivalence trial will compare the two techniques using standardized ultrasound-guided procedures and uniform dosing of ropivacaine adjusted for volume and concentration. All patients will receive the same spinal anesthetic and postoperative analgesia regimen, minimizing confounding factors.

The primary objective is to determine whether IPB provides pain control equivalent to the PENG block during early postoperative mobilization. By assessing patient-reported pain scores, along with recovery quality and opioid use, the study aims to generate evidence that may inform anesthesia planning in joint replacement surgeries and support the integration of newer regional techniques into enhanced recovery protocols.

• Study Type: Interventional
• Enrollment (Estimated): 118
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Michele Carella, MD, PhD, ESRA-DRA; Phone Number: +3242843658; Email: mcarella@chuliege.be

Study Locations

• Belgium
  • Liège, Belgium, 4000
    • Recruiting
    • Liege University Hospital
    • Contact: Michele Carella, MD, PhD, ESRA-DRA; Phone Number: +3242843658; Email: mcarella@chuliege.be

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

Adult patients (age >18 years) ASA physical status classification I-III Scheduled for elective posterior approach total hip arthroplasty (THA) under spinal anesthesia

Exclusion Criteria:

Pregnancy (confirmed by beta-HCG test if applicable) Known peripheral neuropathy or major neurological disease Chronic pain syndromes or long-term opioid use (>20 mg oral morphine equivalents/day) Severe hepatic or renal insufficiency Allergy to local anesthetics Major coagulopathies Vulnerable patients (e.g., minors, legally protected individuals)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Group PENG; Patients will receive a pericapsular nerve group block with 14 ml of ropivacaine 3.75 mg/ml, administered 30 minutes prior to spinal anesthesia.	Procedure: PENG Block; Also performed under ultrasound guidance with an 80 mm B-Braun X360 needle and a 3-5 MHz curved probe. The femoral nerve, femoral artery, iliopsoas muscle, and pubic ramus are identified. The needle is inserted in-plane, and 14 ml of ropivacaine 3.75 mg/ml is injected between the psoas tendon and pubic ramus.
Active Comparator: IPB Group; Patients will receive an iliopsoas plane block with 7 ml of ropivacaine 7.5 mg/ml, administered 30 minutes prior to spinal anesthesia.	Procedure: Iliopsoas nerve block; Performed under ultrasound guidance with a curvilinear probe (5-2 MHz). The transducer is positioned transversely below the anterior superior iliac spine (ASIS), then pivoted medially. After identifying the femoral head and acetabular rim, a 22G 80 mm needle is inserted in-plane to reach the iliopsoas plane, lateral to the iliopsoas tendon. 7 ml of ropivacaine 7.5 mg/ml is then injected.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dynamic Pain 6h postoperative	Dynamic pain score (during mobilization) at 6 hours postoperatively, measured on a 0-10 numeric rating scale (NRS). Equivalence is defined as a mean difference of less than 1 point on the NRS.	6 hours after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total Morphine Consumption	Total morphine consumption at 48 hours on Patient Controlled Intravenous Analgesia device.	First postoperative 48 hours
2MWT	Distance walked in meters during 2-minute at postoperative day 1 and day 2	First postoperative 48 hours
6MWT	Distance walked in meters during 6-minutes test at postoperative day 1 and day 2	First postoperative 48 hours
TUG	Timed Up and Go (TUG) test results at postoperative day 1 and day 2	First postoperative 48 hours
Morphine-related complications	Incidence of opioid-related side effects (nausea, vomiting, constipation, urinary retention, pruritus, dizziness, hypotension)	First postoperative 48 hours
LOS	Length of hospital stay	48 hours after surgery
NRS Dynamic pain	NRS Dynamic pain score (at tight flexion) at 6 hours postoperatively, measured on a 0-10 numeric rating scale (NRS) and at 8 am, 1 pm, 6pm at postoperative day 1 and day 2. No pain: 0; Maximum pain: 10.	First postoperative 48 hours
NRS Rest pain	NRS Rest pain score (no mobilization) at 6 hours postoperatively, measured on a 0-10 numeric rating scale (NRS) and at 8 am, 1 pm, 6pm at postoperative day 1 and day 2. No pain: 0; Maximum pain: 10.	First postoperative 48 hours
QoR-15	Patient recovery scores using the 15-item Quality of Recovery (QoR-15) questionnaire on postoperative days 1 and 2. Minimum: 0; Maximum: 150.	First postoperative 48 hours
IPO	Patient satisfaction using the International Pain Outcomes (IPO) questionnaire at discharge. Each question is a 0 to 10 NRS scale with 0 minimum value and 10 maximum value.	48 hours after surgery

Collaborators and Investigators

• Sponsor: University of Liege
• Collaborators: Centre Hospitalier Universitaire de Liege
• Investigators: Principal Investigator: Michele Carella, MD, PhD, ESRA-DRA, Liege University Hospital

Study record dates

Study Major Dates

• Study Start (Actual): October 1, 2025
• Primary Completion (Estimated): October 1, 2026
• Study Completion (Estimated): October 10, 2026

Study Registration Dates

• First Submitted: April 30, 2025
• First Submitted That Met QC Criteria: April 30, 2025
• First Posted (Actual): May 9, 2025

Study Record Updates

• Last Update Posted (Actual): May 6, 2026
• Last Update Submitted That Met QC Criteria: April 29, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Pain, Postoperative
• Other Study ID Numbers: 2025-172

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Patient data will be anonymized and collected via the REDCap platform, compliant with current data protection regulations. Only the principal investigator and authorized study personnel will have access. Data will be stored securely for 10 years.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No