The Effect of Distal Versus Proximal iPACK on Pain After Total Knee Arthroplasty (eDIPACK)

February 2, 2026 updated by: Comenius University

The Effect of Distal Versus Proximal Approach to the Interspace Between the Popliteal Artery and the Posterior Capsule of the Knee (iPACK) on Pain After Total Knee Arthroplasty

Total knee arthroplasty (TKA) often results in significant postoperative pain, which can hinder recovery despite advances in surgical and anesthetic techniques. Traditional pain management methods like femoral nerve blocks may impair motor function, delaying rehabilitation. The iPACK block, targeting the posterior knee without affecting motor control, offers a promising alternative. This study aims to compare the effectiveness of two iPACK block approaches-proximal (at the distal femoral shaft) and distal (between the femoral condyles)-in managing postoperative pain in TKA patients. In a double-blind, randomized controlled trial with 120 participants, pain scores, opioid use, and time to rescue analgesia will be assessed. The hypothesis is that the distal iPACK block provides superior pain relief, potentially improving patient outcomes and recovery.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Total knee arthroplasty (TKA) is one of the most frequently performed orthopedic procedures in modern medicine. Despite advancements in surgical techniques and perioperative care, postoperative pain management remains a significant challenge and a key factor influencing time to mobilization, patient satisfaction, and length of hospital stay. Commonly used analgesic techniques, such as femoral nerve blocks or epidural analgesia, while effective, can impair motor function and thus delay rehabilitation.

To minimize motor deficits while still providing effective pain relief, newer regional anesthesia techniques have been introduced into clinical practice. One such technique is the iPACK block (interspace between the popliteal artery and posterior capsule of the knee), which targets the posterior knee - an area often insufficiently covered by conventional nerve blocks. This method involves administering a local anesthetic into the space between the popliteal artery and the posterior capsule of the knee joint, offering analgesia without significant motor impairment.

Originally, the iPACK block was described as being performed at the level of the distal femoral shaft, several centimeters above the femoral condyles. Recently, however, a more distal variation of the technique has emerged, where the anesthetic is injected directly between the femoral condyles. This may provide more effective coverage of the posterior knee capsule's innervation. To date, there are no randomized trials that directly compare the efficacy of the distal and proximal iPACK approaches in terms of postoperative pain as the primary outcome.

Our aim is to conduct a prospective, randomized, placebo-controlled, double-blind clinical trial to compare the effectiveness of the distal and proximal iPACK blocks in patients undergoing TKA. A total of 120 patients will be enrolled and randomly assigned to one of two groups.

  • In the proximal iPACK group, participants will receive 20 ml of 0.25% levobupivacaine with adrenaline (1:200,000), injected at the level of the distal femoral shaft (a straight portion of the femur without the condyles).
  • In the distal iPACK group, the same volume and concentration of anesthetic will be injected at the most distal part of the thigh, between the femoral condyles.

All participants, regardless of group assignment, will also receive an adductor canal block with 20 ml of 0.25% levobupivacaine without adrenaline. In addition, all patients will receive standard analgesic therapy consisting of paracetamol (1 g IV every 8 hours) and diclofenac (75 mg IV every 12 hours). If necessary, rescue opioid doses will be available according to individual needs.

The efficacy of each approach will be assessed using several parameters: total opioid consumption within 24 hours and time to first opioid rescue dose, Visual Analogue Scale (VAS) both at rest and during active knee movement (up to 45 degrees) at 6, 12, and 24 hours postoperatively.

The hypothesis of our study is that the distal iPACK approach will provide more effective postoperative pain control compared to the original proximal technique. If confirmed, the findings could influence perioperative pain management protocols for TKA, support the broader adoption of the distal iPACK block in clinical practice, enhance patient comfort, reduce opioid use, promote earlier mobilization, and potentially shorten hospital stays.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
120

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Slovakia
      • Bratislava, Slovakia, 82101
        • Recruiting
        • 1st Department of Anaesthesiology and Intensive Care Medicine
        • Contact:
        • Principal Investigator:
          • Andrej Dano, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age between 18 and 80 years
  • Patients undergoing primary unilateral total knee arthroplasty (TKA) for osteoarthritis
  • Ability to understand and sign informed consent
  • American Society of Anesthesiologists (ASA) classification I-III
  • Ability to cooperate and participate in postoperative pain assessments (e.g., VAS)

Exclusion Criteria:

  • Refusal to participate or failure to sign informed consent
  • Bilateral or revision TKA
  • Partial or unicondylar knee replacement
  • Severe knee deformity (flexion, varus, or valgus >30°)
  • Diagnosis other than osteoarthritis (e.g., rheumatoid arthritis, septic arthritis, post-traumatic arthritis)
  • Allergy to local anesthetics or any medications used in the study
  • Contraindications to regional anesthesia (e.g., infection at the injection site, coagulopathy, therapeutic anticoagulation)
  • BMI > 40 kg/m²
  • Severe renal impairment (KDIGO stage G4 or higher) or liver failure (Child-Pugh score ≥ 10)
  • Prior surgery or vascular procedure on the femoral vessels of the operated limb
  • Language barrier or inability to assess pain using the VAS
  • Planned outpatient (same-day discharge) procedure

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: proximal iPACK group
In the proximal iPACK group, participants will receive 20 ml of 0.25% levobupivacaine with adrenaline (1:200,000), injected at the level of the distal femoral shaft (a straight portion of the femur without the condyles).
Procedure: proximal iPACK
● In the proximal iPACK group, participants will receive 20 ml of 0.25% levobupivacaine with adrenaline (1:200,000), injected at the level of the distal femoral shaft (a straight portion of the femur without the condyles).
Experimental: distal iPACK group
In the distal iPACK group, the participants will receive 20 ml of 0.25% levobupivacaine with adrenaline (1:200,000), injected at the most distal part of the thigh, between the femoral condyles.
Procedure: distal iPACK
● In the distal iPACK group, participants will receive 20 ml of 0.25% levobupivacaine with adrenaline (1:200,000), injected at the most distal part of the thigh, between the femoral condyles.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
total opioids consumption
Time Frame: from surgery until 24 hours after surgery
total opioids consumption calculated to MME (morphine milligrams equivalent)
from surgery until 24 hours after surgery

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
time to first opioid administration
Time Frame: up to 24 hours after surgery
time to first opioid administration time in hours to first opioid administration after operation.
up to 24 hours after surgery
Visual analog scale 6 (rest)
Time Frame: 6 hours postoperatively
pain intensity will be measured using the Visual Analogue Scale at rest 6 hours postoperatively. The Visual Analogue Scale is a validated, 100-mm horizontal line used to measure pain intensity, ranging from "no pain" (0 mm) to "worst possible pain" (100 mm).
6 hours postoperatively
Visual analog scale 12 (rest)
Time Frame: 12 hours postoperatively
pain intensity will be measured using the Visual Analogue Scale at rest 12 hours postoperatively. The Visual Analogue Scale is a validated, 100-mm horizontal line used to measure pain intensity, ranging from "no pain" (0 mm) to "worst possible pain" (100 mm).
12 hours postoperatively
Visual analog scale 24 (rest)
Time Frame: 24 hours postoperatively
pain intensity will be measured using the Visual Analogue Scale at rest 24 hours postoperatively, The Visual Analogue Scale is a validated, 100-mm horizontal line used to measure pain intensity, ranging from "no pain" (0 mm) to "worst possible pain" (100 mm).
24 hours postoperatively
Visual analog scale 6 (flexion)
Time Frame: 6 hours postoperatively
pain intensity will be measured using the Visual Analogue Scale at 45° flexion in the knee 6 hours postoperatively. The Visual Analogue Scale is a validated, 100-mm horizontal line used to measure pain intensity, ranging from "no pain" (0 mm) to "worst possible pain" (100 mm).
6 hours postoperatively
Visual analog scale 12 (flexion)
Time Frame: 12 hours postoperatively
pain intensity will be measured using the Visual Analogue Scale at 45° flexion in the knee 12 hours postoperatively. The Visual Analogue Scale is a validated, 100-mm horizontal line used to measure pain intensity, ranging from "no pain" (0 mm) to "worst possible pain" (100 mm).
12 hours postoperatively
Visual analog scale 24 (flexion)
Time Frame: 24 hours postoperatively
pain intensity will be measured using the Visual Analogue Scale at 45° flexion in the knee 24 hours postoperatively. The Visual Analogue Scale is a validated, 100-mm horizontal line used to measure pain intensity, ranging from "no pain" (0 mm) to "worst possible pain" (100 mm).
24 hours postoperatively

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Comenius University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
February 12, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
May 30, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 15, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 15, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
July 23, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 4, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 2, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • UNB/RU/052025

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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