iPACK Block vs. Periarticular Infiltration for TKA Pain Control

May 28, 2026 updated by: Muhammed Celil Aslan, Turgutlu State Hospital

Postoperative Analgesic Outcomes of iPACK Block Versus Periarticular Infiltration in Total Knee Arthroplasty: A Retrospective Cohort Study

This study aims to retrospectively compare two different multimodal analgesic techniques for pain management after total knee arthroplasty (TKA). The primary purpose is to evaluate whether a combination of two specific nerve blocks administered by an anesthesiologist (Femoral Triangle Block + iPACK block) resulted in superior postoperative pain control compared to a hybrid combination of a nerve block and a local infiltration administered by the surgeon (FTB + Periarticular Infiltration [PAI]).

The hypothesis is that the FTB + iPACK combination is associated with a significant reduction in Numeric Rating Scale (NRS) pain scores with movement at 24 hours postoperatively. This is a retrospective, observational cohort study conducted at a single center, involving medical records of patients who underwent primary unilateral TKA. Data from patients who received either FTB + iPACK or FTB + PAI as part of their standard clinical care will be extracted and analyzed retrospectively.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Total knee arthroplasty (TKA) is a highly successful procedure for end-stage knee osteoarthritis but is associated with significant postoperative pain. Effective pain management is crucial for facilitating early rehabilitation and improving patient comfort. Modern pain management relies on multimodal, opioid-sparing protocols that often include motor-sparing regional anesthesia techniques like the femoral triangle block (FTB).

While FTB provides excellent analgesia for the anterior part of the knee, pain originating from the posterior knee capsule remains a significant challenge. This posterior pain is commonly managed either by the surgeon through a diffuse periarticular infiltration (PAI) of a local anesthetic cocktail or by the anesthesiologist through a targeted, ultrasound-guided block of the posterior capsule known as the iPACK block.

It is currently unclear whether a fully anesthesiologist-driven, neuroanatomically targeted approach (FTB + iPACK) offers superior clinical outcomes compared to a hybrid approach involving both the anesthesiologist and the surgeon (FTB + PAI). This retrospective study is designed to compare the clinical efficacy of these two advanced analgesic combinations by reviewing institutional patient registries. All included patients had previously received a standardized spinal anesthetic (3 mL of 0.5% heavy bupivacaine) followed by either of the regional analgesia protocols. The study evaluates postoperative pain control, measured primarily by Numeric Rating Scale (NRS) pain scores at 24 hours. Secondary outcomes include total rescue analgesic (tramadol) consumption, functional recovery (Timed Up and Go test and Straight Leg Raise test), and knee range of motion.

Study Type

Observational

Enrollment (Estimated)

100

Phase

  • 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 Locations

  • Turkey (Türkiye)
    • Manisa
      • Manisa, Manisa, Turkey (Türkiye), 45000
        • Turgutlu State Hospital+

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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

The study population consists of adult patients who underwent elective, primary, unilateral total knee arthroplasty (TKA) under spinal anesthesia at Turgutlu State Hospital. Patient records and institutional registries will be reviewed retrospectively to identify eligible cases managed within a specific operational period (e.g., between December 2025 and May 2026). The cohort includes patients who received either an ultrasound-guided Femoral Triangle Block combined with an iPACK block or a hybrid combination of Femoral Triangle Block and surgeon-administered Periarticular Infiltration for postoperative analgesia as part of standard clinical care.

Description

Inclusion Criteria:

  • American Society of Anesthesiologists (ASA) physical status II-III.
  • Scheduled for elective, primary, unilateral total knee arthroplasty for osteoarthritis.
  • Able to provide written informed consent.

Exclusion Criteria:

  • Patient refusal to participate or contraindication to regional anesthesia.
  • Known allergy to any study medications (local anesthetics, NSAIDs, tramadol, morphine, paracetamol).
  • History of chronic opioid use (defined as daily use for >3 months)
  • Pre-existing peripheral neuropathy in the operative limb.
  • Severe renal or hepatic insufficiency.
  • Cognitive impairment preventing the use of pain scales or questionnaires.
  • Revision or bilateral knee arthroplasty.

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

Cohorts and Interventions

Group / Cohort
FTB + iPACK Group
Patients who underwent primary unilateral TKA and received FTB + iPACK block as part of standard clinical care.
FTB + PAI Group
Patients who underwent primary unilateral TKA and received FTB + PAI as part of standard clinical care.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative Pain Score with Movement at 24 Hours
Time Frame: 24 and 48. hours postoperatively
Pain assessed via Numeric Rating Scale (NRS) during active movement (e.g., active knee flexion or straight leg raise). Scale: 0 (no pain) to 10 (worst pain imaginable).
24 and 48. hours postoperatively

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative Pain Scores (Time-Course)
Time Frame: Assessed at 6, 12, and 24 hours postoperatively
Numeric Rating Scale (NRS) for pain (0-10) assessed at rest and with movement.
Assessed at 6, 12, and 24 hours postoperatively
Time Up to Go Test
Time Frame: Assessed at 24 hours
The time taken (in seconds) for the participant to stand up from a standard armchair, walk a distance of 3 meters, turn, walk back to the chair, and sit down. Lower values indicate better functional mobility.
Assessed at 24 hours
Straight Leg Raise
Time Frame: Postoperative 24. hour
Assessment of active quadriceps motor function. Defined as the participant's ability to actively lift the operated leg off the bed with the knee fully extended (straight). This will be assessed as a binary outcome (Success = Able to lift unassisted / Failure = Unable to lift).
Postoperative 24. hour
Knee Range of Motion (ROM)
Time Frame: Baseline (Preoperative) and 24 hours postoperatively
Active knee flexion (in degrees)
Baseline (Preoperative) and 24 hours postoperatively
Time to First Rescue Analgesia
Time Frame: First 24 postoperative hours
Time (in minutes) from the end of surgery to the first patient request for rescue tramadol.
First 24 postoperative hours
Incidence of Adverse Events
Time Frame: First 48 hours.
Incidence of postoperative nausea/vomiting (PONV) and pruritus.
First 48 hours.

Collaborators and Investigators

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

Sponsor

Turgutlu State Hospital

Investigators

  • Principal Investigator: Aslan, Turgutlu State Hospital

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 (Estimated)

May 1, 2026

Primary Completion (Actual)

May 1, 2026

Study Completion (Estimated)

August 1, 2026

Study Registration Dates

First Submitted

November 16, 2025

First Submitted That Met QC Criteria

December 4, 2025

First Posted (Actual)

December 5, 2025

Study Record Updates

Last Update Posted (Actual)

June 1, 2026

Last Update Submitted That Met QC Criteria

May 28, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ANES-TKA-2025-001

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

All the patient statistics

IPD Sharing Supporting Information Type

  • SAP
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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