ACB and iPACK Blocks With Intravenous Dexamethasone and Perineural Dexmedetomidine in Total Knee Arthroplasty

Comparison of the Efficacy and Safety of Three Adjuvant Strategies for ACB and iPACK Blocks in Patients Undergoing Elective Total Knee Arthroplasty: A Prospective, Randomized Clinical Trial

This prospective randomized controlled trial aims to compare the analgesic efficacy and safety of three adjuvant strategies for ultrasound-guided Adductor Canal Block (ACB) and iPACK block in patients undergoing elective total knee arthroplasty under spinal anesthesia. All participants will receive standardized spinal anesthesia with 0.5% ropivacaine combined with ACB and iPACK blocks using 0.2% ropivacaine. Patients will be randomized into one of three groups: standard ACB + iPACK without adjuvants, ACB + iPACK with intravenous dexamethasone 8 mg, or ACB + iPACK with intravenous dexamethasone 8 mg combined with perineural dexmedetomidine added to both regional blocks.

The primary outcome will be total postoperative opioid consumption during the first 48 hours after surgery expressed as intravenous morphine equivalents. Secondary outcomes will include pain intensity at rest and during movement, duration of analgesia, time to first rescue analgesia, quadriceps muscle strength, early mobilization, adverse events, inflammatory markers, and length of hospital stay.

Study Overview

• Status: Not yet recruiting
• Conditions: Knee Osteoarthritis
• Intervention / Treatment: Drug: Ropivacaine 0.2% Injectable Solution; Drug: Dexamethasone; Drug: Dexmedetomidine

Detailed Description

Postoperative pain following total knee arthroplasty (TKA) remains a major clinical challenge and may negatively affect early mobilization, rehabilitation, patient satisfaction, and postoperative recovery. Inadequate pain control after TKA is associated with increased opioid consumption and opioid-related adverse events, including nausea, vomiting, sedation, urinary retention, respiratory depression, and postoperative delirium, particularly in elderly patients.

Ultrasound-guided Adductor Canal Block (ACB) combined with iPACK (Infiltration between the Popliteal Artery and Capsule of the Knee) block has become an increasingly popular regional anesthesia strategy for TKA because it may provide effective analgesia while preserving quadriceps muscle strength and facilitating early mobilization. The ACB primarily targets the sensory innervation of the anterior and medial aspects of the knee, whereas the iPACK block supplements analgesia of the posterior knee capsule.

Several adjuvant medications have been investigated to prolong the duration and improve the quality of peripheral nerve blocks. Intravenous dexamethasone is widely used as a perioperative analgesic adjunct and may prolong postoperative analgesia while also reducing postoperative nausea and vomiting. Perineural dexmedetomidine has been shown to prolong sensory blockade, improve analgesia quality, and reduce opioid requirements. However, the optimal combination of systemic and perineural adjuvants for ACB and iPACK blocks in TKA remains unclear.

The aim of this prospective randomized controlled trial is to compare three perioperative analgesic strategies in patients undergoing elective primary unilateral total knee arthroplasty under spinal anesthesia:

Standard ACB + iPACK without adjuvants, ACB + iPACK with intravenous dexamethasone 8 mg, ACB + iPACK with intravenous dexamethasone 8 mg combined with perineural dexmedetomidine.

All participants will receive standardized spinal anesthesia with 0.5% ropivacaine (3-4 mL). Ultrasound-guided ACB and iPACK blocks will be performed using 20 mL of 0.2% ropivacaine for each block. In the dexmedetomidine group, 12.5 µg of dexmedetomidine will be added to each regional block.

The primary endpoint of the study will be total postoperative opioid consumption during the first 48 postoperative hours expressed as intravenous morphine equivalents. Secondary endpoints will include postoperative pain scores at rest and during movement, time to first rescue analgesia, duration of analgesia, quadriceps muscle strength, early mobilization, opioid-related adverse events, dexmedetomidine-related adverse events such as bradycardia and hypotension, inflammatory markers, and length of hospital stay.

The study hypothesis is that intravenous dexamethasone will improve postoperative analgesia compared with standard ACB + iPACK alone, while the addition of low-dose perineural dexmedetomidine will further prolong analgesia duration and reduce opioid consumption without significantly increasing adverse events or impairing postoperative mobilization.

• Study Type: Interventional
• Enrollment (Estimated): 120
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Malgorzata Reysner, MD PhD; Phone Number: +48 61 8310122; Email: mreysner@ump.edu.pl
• Study Contact Backup: Name: Tomasz Reysner, MD PhD; Phone Number: +48 61 8310122; Email: treysner@ump.edu.pl

Study Locations

• Poland
  • Lublin, Poland
    • The John Paul II Catholic University of Lublin
    • Contact: Michał Borys, MD PhD
  • Poznan, Poland, 62-701
    • Poznan University of Medical Sciences

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Age between 60 and 100 years
• Scheduled for elective primary unilateral total knee arthroplasty
• American Society of Anesthesiologists (ASA) physical status I-III
• Ability to understand study procedures and provide written informed consent
• Eligibility for spinal anesthesia and ultrasound-guided regional anesthesia according to institutional standards

Exclusion Criteria:

• Known allergy or hypersensitivity to ropivacaine, dexamethasone, dexmedetomidine, or any study-related medication
• Contraindications to spinal anesthesia or peripheral nerve blocks
• Coagulation disorders or anticoagulant therapy preventing safe regional anesthesia
• Infection at the planned puncture site or systemic infection
• Severe neurological disorders affecting lower limb sensory or motor function
• Severe hepatic, renal, or uncontrolled cardiovascular disease
• Clinically significant bradycardia or advanced atrioventricular conduction abnormalities
• Chronic opioid use for more than 3 months before surgery
• Uncontrolled diabetes mellitus or contraindications to dexamethasone administration
• Inability or refusal to provide written informed consent

Study Plan

How is the study designed?

Design Details

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

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: ACB + iPACK Without Adjuvants; Participants will receive standardized spinal anesthesia with 0.5% ropivacaine (3-4 mL) combined with ultrasound-guided Adductor Canal Block (ACB) and iPACK block using 20 mL of 0.2% ropivacaine for each block. No adjuvant medications will be administered. Standardized multimodal postoperative analgesia will be provided according to institutional protocol.	Drug: Ropivacaine 0.2% Injectable Solution; Ropivacaine 0.2% used for ultrasound-guided ACB and iPACK blocks (20 mL per block).; Other Names: Ropimol
Experimental: ACB + iPACK With Intravenous Dexamethasone; Participants will receive standardized spinal anesthesia with 0.5% ropivacaine (3-4 mL) combined with ultrasound-guided Adductor Canal Block (ACB) and iPACK block using 20 mL of 0.2% ropivacaine for each block. Intravenous dexamethasone 8 mg will be administered perioperatively. Standardized multimodal postoperative analgesia will be provided according to institutional protocol.	Drug: Dexamethasone; Intravenous dexamethasone 8 mg administered perioperatively.; Other Names: Dexaven
Experimental: ACB + iPACK With Intravenous Dexamethasone and Perineural Dexmedetomidine; Participants will receive standardized spinal anesthesia with 0.5% ropivacaine (3-4 mL) combined with ultrasound-guided Adductor Canal Block (ACB) and iPACK block using 20 mL of 0.2% ropivacaine for each block. Perineural dexmedetomidine 12.5 µg will be added to each regional block. Intravenous dexamethasone 8 mg will be administered perioperatively. Standardized multimodal postoperative analgesia will be provided according to institutional protocol.	Drug: Dexmedetomidine; Perineural dexmedetomidine 12.5 μg added to each regional block (ACB and iPACK).; Other Names: Dexdor

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total postoperative opioid consumption during the first 48 hours after surgery	Total postoperative opioid consumption will be recorded during the first 48 hours after total knee arthroplasty and converted to intravenous morphine milligram equivalents.	48 hours after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pain intensity at rest	Pain intensity at rest will be assessed using the Numeric Rating Scale, where 0 indicates no pain and 10 indicates the worst imaginable pain.	6 hours after surgery
Pain intensity at rest	Pain intensity at rest will be assessed using the Numeric Rating Scale, where 0 indicates no pain and 10 indicates the worst imaginable pain.	12 hours after surgery
Pain intensity at rest	Pain intensity at rest will be assessed using the Numeric Rating Scale, where 0 indicates no pain and 10 indicates the worst imaginable pain.	24 hours after surgery
Pain intensity at rest	Pain intensity at rest will be assessed using the Numeric Rating Scale, where 0 indicates no pain and 10 indicates the worst imaginable pain.	48 hours after surgery
Pain intensity during movement assessed using the Numeric Rating Scale	Pain intensity during movement will be assessed using the Numeric Rating Scale during active or passive knee movement, where 0 indicates no pain and 10 indicates the worst imaginable pain.	6 hours postoperatively
Pain intensity during movement assessed using the Numeric Rating Scale	Pain intensity during movement will be assessed using the Numeric Rating Scale during active or passive knee movement, where 0 indicates no pain and 10 indicates the worst imaginable pain.	12 hours postoperatively
Pain intensity during movement assessed using the Numeric Rating Scale	Pain intensity during movement will be assessed using the Numeric Rating Scale during active or passive knee movement, where 0 indicates no pain and 10 indicates the worst imaginable pain.	24 hours postoperatively
Pain intensity during movement assessed using the Numeric Rating Scale	Pain intensity during movement will be assessed using the Numeric Rating Scale during active or passive knee movement, where 0 indicates no pain and 10 indicates the worst imaginable pain.	48 hours postoperatively
Time to first rescue analgesia	Time from the end of surgery to the first request for or administration of rescue analgesic medication.	48 hours after surgery
Quadriceps muscle strength of the operated limb	Quadriceps muscle strength of the operated limb will be assessed using a standardized motor strength scale.	6 hours postoperatively
Quadriceps muscle strength of the operated limb	Quadriceps muscle strength of the operated limb will be assessed using a standardized motor strength scale.	12 hours postoperatively
Quadriceps muscle strength of the operated limb	Quadriceps muscle strength of the operated limb will be assessed using a standardized motor strength scale.	24 hours postoperatively
Quadriceps muscle strength of the operated limb	Quadriceps muscle strength of the operated limb will be assessed using a standardized motor strength scale.	48 hours postoperatively
Time to first postoperative mobilization	Time from the end of surgery to the first successful mobilization with assistance, according to the institutional rehabilitation protocol.	48 hours postoperatively
Length of hospital stay	Length of hospital stay will be defined as the number of days from surgery to hospital discharge.	up to 7 days

Collaborators and Investigators

• Sponsor: Poznan University of Medical Sciences
• Investigators: Study Chair: Malgorzata Reysner, MD PhD, Poznan University of Medical Sciences; Study Director: Michał Borys, MD PhD, The John Paul II Catholic University of Lublin

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): September 1, 2027
• Study Completion (Estimated): October 1, 2027

Study Registration Dates

• First Submitted: May 20, 2026
• First Submitted That Met QC Criteria: June 29, 2026
• First Posted (Actual): June 30, 2026

Study Record Updates

• Last Update Posted (Actual): June 30, 2026
• Last Update Submitted That Met QC Criteria: June 29, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Osteoarthritis; Osteoarthritis, Knee; Organic Chemicals; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Azoles; Polycyclic Compounds; Imidazoles; Anilides; Amides; Aniline Compounds; Amines; Pregnadienes; Pregnanes; Steroids; Fused-Ring Compounds; Steroids, Fluorinated; Pregnadienetriols; Ropivacaine; Dexamethasone; Dexmedetomidine
• Other Study ID Numbers: 6/2026

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data underlying the reported results will be made available to qualified researchers upon reasonable request after publication of the primary study results. Shared data may include demographic data, perioperative variables, postoperative pain scores, opioid consumption, adverse events, and other study-related outcomes. Data will be provided after removal of all direct identifiers in accordance with applicable data protection regulations.
• IPD Sharing Time Frame: Data will become available beginning 6 months after publication of the primary study results and will remain available for 5 years.
• IPD Sharing Access Criteria: Access to de-identified participant data will be provided to researchers whose proposed use of the data has been approved by the principal investigators. Requests should include a methodologically sound research proposal. Data sharing agreements may be required before data release.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; 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