PENG Block and Delirium After Hip Arthroplasty

Effect of Pericapsular Nerve Group (PENG) Block Added to Spinal Anesthesia on Postoperative Delirium in Older Adults Undergoing Primary Total Hip Arthroplasty: A Prospective, Randomized, Assessor-Blinded Controlled Trial

Postoperative delirium is a common and serious complication in older adults undergoing total hip arthroplasty, associated with prolonged hospitalization, increased morbidity, delayed rehabilitation, and long-term cognitive decline. Modifiable perioperative risk factors include uncontrolled postoperative pain, opioid consumption, impaired early mobilization, and systemic inflammatory response.

The Pericapsular Nerve Group (PENG) block is a regional anesthesia technique targeting the sensory innervation of the anterior hip capsule and may provide effective analgesia while preserving motor function. Improved pain control and opioid reduction may decrease the incidence of postoperative delirium.

This prospective, randomized, parallel-group controlled trial aims to evaluate whether the addition of ultrasound-guided PENG block to spinal anesthesia reduces the incidence of postoperative delirium within 72 hours after primary total hip arthroplasty in patients aged 65 years or older. Delirium will be assessed using the Confusion Assessment Method (CAM) by blinded outcome assessors.

Secondary outcomes include postoperative opioid consumption, pain intensity (NRS), time to first rescue opioid, postoperative nausea and vomiting, time to mobilization, block-related adverse events, and perioperative inflammatory indices (neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and monocyte-to-lymphocyte ratio).

The study will enroll 144 patients randomized 1:1 to spinal anesthesia alone or spinal anesthesia plus PENG block.

Study Overview

• Status: Recruiting
• Conditions: Hip Osteoarthritis
• Intervention / Treatment: Drug: sham block with 0.9% sodium chloride; Drug: 0.2% ropivacaine

Detailed Description

Postoperative delirium is a frequent and serious complication in older adults undergoing major orthopedic surgery, including total hip arthroplasty. Its incidence in this population ranges from 10% to 30% and is associated with prolonged hospital stay, increased healthcare costs, delayed functional recovery, long-term cognitive impairment, and increased mortality. Among modifiable perioperative risk factors, inadequate pain control, higher opioid consumption, postoperative nausea and vomiting, sleep disturbances, delayed mobilization, and systemic inflammatory response play an important role.

Regional anesthesia techniques may reduce delirium risk by improving analgesia, decreasing opioid requirements, and attenuating surgical stress and inflammatory response. The Pericapsular Nerve Group (PENG) block is an ultrasound-guided regional anesthesia technique targeting the articular branches supplying the anterior hip capsule. It has been shown to provide effective analgesia after hip surgery while largely preserving quadriceps motor function, potentially facilitating early mobilization.

This study is a prospective, randomized, parallel-group controlled trial designed to evaluate whether the addition of ultrasound-guided PENG block to spinal anesthesia reduces the incidence of postoperative delirium in patients aged 65 years or older undergoing primary elective total hip arthroplasty.

Eligible patients (ASA II-III) will be randomized in a 1:1 ratio to receive:

spinal anesthesia with standard multimodal postoperative analgesia (control group), or spinal anesthesia combined with ultrasound-guided PENG block plus standard multimodal postoperative analgesia (intervention group).

Randomization will be computer-generated with concealed allocation. Outcome assessors evaluating delirium and functional endpoints will be blinded to group assignment. The anesthesiologist performing the block cannot be blinded but will not participate in postoperative outcome assessment.

The primary endpoint is the incidence of postoperative delirium within 72 hours after surgery, assessed at least once daily using the Confusion Assessment Method (CAM) by trained, blinded personnel. Documentation review for delirium-related symptoms and use of antidelirium medications will complement, but not replace, structured CAM assessment.

Secondary endpoints include cumulative opioid consumption during the first 48 postoperative hours (expressed as morphine milligram equivalents), pain intensity at rest and during movement (Numeric Rating Scale), time to first rescue opioid administration, incidence of postoperative nausea and vomiting, time to first mobilization, and block-related adverse events.

Additionally, perioperative inflammatory response will be explored using routinely collected complete blood count parameters. Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) will be calculated at predefined time points (baseline, 24 hours, and 48 hours postoperatively). Exploratory analyses will assess associations between these inflammatory indices and postoperative delirium.

The planned sample size is 144 patients (72 per group), calculated to detect a clinically relevant reduction in delirium incidence with 80% power and a two-sided alpha of 0.05, accounting for potential dropouts.

The study will be conducted in accordance with the Declaration of Helsinki and Good Clinical Practice principles. Written informed consent will be obtained from all participants prior to enrollment.

• Study Type: Interventional
• Enrollment (Estimated): 180
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Malgorzata Reysner, MD PhD; Phone Number: +48 61 8320122; Email: mreysner@ump.edu.pl
• Study Contact Backup: Name: Malgorzata Reysner, MD PhD; Phone Number: +48 501056924; Email: mreysner@ump.edu.pl

Study Locations

• Poland
  • Poznan, Poland, 62-701
    • Recruiting
    • Poznan University of Medical Sciences
    • Contact: Malgorzata Reysner, M.D. Ph.D.; Phone Number: +48 61 873 83 03; Email: mreysner@ump.edu.pl

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Age ≥ 75 years
• Scheduled for elective primary total hip arthroplasty
• Planned spinal anesthesia
• ASA physical status II-III
• Ability to provide written informed consent
• Ability to communicate and reliably assess pain using the Numeric Rating Scale (NRS)
• Expected postoperative hospitalization ≥ 72 hours

Exclusion Criteria:

• Pre-existing delirium, acute psychosis, or active major psychiatric disorder
• Documented severe dementia or inability to provide informed consent
• Severe hearing or visual impairment preventing reliable CAM assessment
• Contraindications to regional anesthesia (e.g., coagulopathy according to institutional standards, infection at the injection site, allergy to local anesthetics)
• Pre-existing neurological deficits of the operative lower limb are interfering with assessment
• Chronic opioid use (>30 mg morphine milligram equivalents per day for >2 weeks prior to surgery)
• Severe renal impairment (eGFR <30 mL/min/1.73 m²)
• Severe hepatic insufficiency
• Participation in another interventional clinical trial within 30 days
• Any other condition that, in the investigator's judgment, may interfere with study participation or protocol adherence

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: PENG block; PENG block with 20ml 0f 0.2% ropivacaine	Drug: 0.2% ropivacaine; After spinal anesthesia, the ultrasound-guided PENG block will be performed with 20 ml of 0.2% ropivacaine; Other Names: PENG block with 0.2% ropivacaine
Placebo Comparator: Sham Block; PENG block with 20ml of 0.9% sodium chloride	Drug: sham block with 0.9% sodium chloride; After spinal anesthesia, the ultrasound-guided PENG block will be performed with 20ml of 0.9% sodium chloride

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of postoperative delirium	Incidence of postoperative delirium within 72 hours after surgery, defined as at least one positive Confusion Assessment Method (CAM) assessment (CAM+) at any of the prespecified postoperative time points. CAM will be administered by trained assessors blinded to group allocation. The primary endpoint will be recorded as a binary outcome (delirium: yes/no)	12 hours after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of Postoperative Delirium	Incidence of postoperative delirium within 72 hours after surgery, defined as at least one positive Confusion Assessment Method (CAM) assessment (CAM+) at any of the prespecified postoperative time points. CAM will be administered by trained assessors blinded to group allocation. The primary endpoint will be recorded as a binary outcome (delirium: yes/no)	24 hours after surgery
Incidence of Postoperative Delirium	Incidence of postoperative delirium within 72 hours after surgery, defined as at least one positive Confusion Assessment Method (CAM) assessment (CAM+) at any of the prespecified postoperative time points. CAM will be administered by trained assessors blinded to group allocation. The primary endpoint will be recorded as a binary outcome (delirium: yes/no)	48 hours after surgery
Incidence of Postoperative Delirium	Incidence of postoperative delirium within 72 hours after surgery, defined as at least one positive Confusion Assessment Method (CAM) assessment (CAM+) at any of the prespecified postoperative time points. CAM will be administered by trained assessors blinded to group allocation. The primary endpoint will be recorded as a binary outcome (delirium: yes/no)	72 hours after surgery
Cumulative Postoperative Opioid Consumption (MME)	Total opioid consumption during the first 48 hours after surgery, converted to morphine milligram equivalents (MME). Includes all rescue opioids administered intravenously or orally	48 hours after surgery
Postoperative Pain Intensity (NRS)	Pain intensity assessed using the 11-point Numeric Rating Scale (NRS, 0 = no pain, 10 = worst imaginable pain) at rest and during movement.	4 hours after surgery
Postoperative Pain Intensity (NRS)	Pain intensity assessed using the 11-point Numeric Rating Scale (NRS, 0 = no pain, 10 = worst imaginable pain) at rest and during movement.	8 hours after surgery
Postoperative Pain Intensity (NRS)	Pain intensity assessed using the 11-point Numeric Rating Scale (NRS, 0 = no pain, 10 = worst imaginable pain) at rest and during movement.	12 hours after surgery
Postoperative Pain Intensity (NRS)	Pain intensity assessed using the 11-point Numeric Rating Scale (NRS, 0 = no pain, 10 = worst imaginable pain) at rest and during movement.	24 hours after surgery
Postoperative Pain Intensity (NRS)	Pain intensity assessed using the 11-point Numeric Rating Scale (NRS, 0 = no pain, 10 = worst imaginable pain) at rest and during movement.	48 hours after surgery
Postoperative Pain Intensity (NRS)	Pain intensity assessed using the 11-point Numeric Rating Scale (NRS, 0 = no pain, 10 = worst imaginable pain) at rest and during movement.	72 hours after surgery
Time to First Rescue Opioid Administration	Time (in hours) from arrival in the postoperative recovery area to the first administration of rescue opioid analgesia.	48 hours after surgery
Incidence of Postoperative Nausea and Vomiting (PONV)	Occurrence of nausea and/or vomiting requiring pharmacological treatment during the early postoperative period.	24 hours after surgery
Time to First Mobilization	Time (in hours) from the end of surgery to first assisted mobilization (e.g., standing or ambulation with physiotherapist support).	72 hours after surgery
Systemic Inflammation Response Index (SIRI)	Systemic Inflammation Response Index (SIRI) is used as a composite marker of systemic inflammatory activation. It is calculated from peripheral venous blood samples using the formula: SIRI = (Neutrophil count × Monocyte count) / Lymphocyte count All parameters are obtained from routine complete blood count (CBC) analysis and expressed in ×10⁹/L. SIRI reflects the interaction between innate immune activation (neutrophils and monocytes) and adaptive immune suppression (lymphocytes). Higher SIRI values indicate greater systemic inflammatory response.	12 hours after surgery
Systemic Inflammation Response Index (SIRI)	Systemic Inflammation Response Index (SIRI) is used as a composite marker of systemic inflammatory activation. It is calculated from peripheral venous blood samples using the formula: SIRI = (Neutrophil count × Monocyte count) / Lymphocyte count All parameters are obtained from routine complete blood count (CBC) analysis and expressed in ×10⁹/L. SIRI reflects the interaction between innate immune activation (neutrophils and monocytes) and adaptive immune suppression (lymphocytes). Higher SIRI values indicate greater systemic inflammatory response.	24 hours after surgery
Systemic Inflammation Response Index (SIRI)	Systemic Inflammation Response Index (SIRI) is used as a composite marker of systemic inflammatory activation. It is calculated from peripheral venous blood samples using the formula: SIRI = (Neutrophil count × Monocyte count) / Lymphocyte count All parameters are obtained from routine complete blood count (CBC) analysis and expressed in ×10⁹/L. SIRI reflects the interaction between innate immune activation (neutrophils and monocytes) and adaptive immune suppression (lymphocytes). Higher SIRI values indicate greater systemic inflammatory response.	48 hours after surgery
Systemic Inflammation Response Index (SIRI)	Systemic Inflammation Response Index (SIRI) is used as a composite marker of systemic inflammatory activation. It is calculated from peripheral venous blood samples using the formula: SIRI = (Neutrophil count × Monocyte count) / Lymphocyte count All parameters are obtained from routine complete blood count (CBC) analysis and expressed in ×10⁹/L. SIRI reflects the interaction between innate immune activation (neutrophils and monocytes) and adaptive immune suppression (lymphocytes). Higher SIRI values indicate greater systemic inflammatory response.	72 hours after surgery

Collaborators and Investigators

• Sponsor: Poznan University of Medical Sciences

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2026
• Primary Completion (Estimated): May 1, 2027
• Study Completion (Estimated): June 30, 2027

Study Registration Dates

• First Submitted: February 27, 2026
• First Submitted That Met QC Criteria: February 27, 2026
• First Posted (Actual): March 4, 2026

Study Record Updates

• Last Update Posted (Actual): May 22, 2026
• Last Update Submitted That Met QC Criteria: May 20, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Osteoarthritis; Osteoarthritis, Hip; Organic Chemicals; Anilides; Amides; Aniline Compounds; Amines; Inorganic Chemicals; Chlorine Compounds; Sodium Compounds; Chlorides; Hydrochloric Acid; Ropivacaine; Sodium Chloride
• Other Study ID Numbers: 87/26

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

De-identified individual participant data (IPD) underlying the results reported in publications (including demographic data, laboratory inflammatory indices such as SII, SIRI, AISI, CRP values, pain scores, opioid consumption, and time-to-event outcomes) will be made available to qualified researchers.

Data will be shared after removal of all direct identifiers in accordance with GDPR regulations and institutional data protection policies.

The study protocol, statistical analysis plan (SAP), and analytic code will also be available upon reasonable request.

Data will be provided for the purpose of secondary analyses, meta-analyses, or validation studies, subject to approval by the principal investigator and institutional review board, where applicable.

• IPD Sharing Time Frame: Data will become available 6 months after publication of the primary results and will remain available for 5 years.
• IPD Sharing Access Criteria: A methodologically sound research proposal Institutional affiliation Ethical approval (if required) A signed data use agreement Requests should be directed to the principal investigator via institutional email.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ANALYTIC_CODE

Drug and device information, study documents

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