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Understanding the iPACK Block: A Comprehensive Guide

The iPACK block, or Infiltration between the Popliteal Artery and Capsule of the Knee, is a regional anesthesia technique gaining popularity in pain management, particularly after knee surgeries. This guide delves into the iPACK block's procedure, advantages, effectiveness, and potential complications.

What is an iPACK Block?

The iPACK block targets the articular branches of the nerves that innervate the posterior aspect of the knee, specifically the tibial, common peroneal, and obturator nerves. It's a motor-sparing intervention that allows for pain relief without causing foot drop, a common side effect of a complete sciatic nerve block.

How is an iPACK Block Performed?

Performing an iPACK block involves several steps under ultrasound guidance:

1.         Patient Positioning: The patient is positioned either prone or supine, with the hip abducted and the knee flexed.

2.         Ultrasound Probe Placement: A high-frequency linear probe is placed transversely at the popliteal crease.

3.         Sonoanatomy Identification: The femoral condyles and the popliteal artery are identified on the ultrasound.

4.         Needle Insertion: A long thin needle is inserted in-plane to the space between the popliteal artery and the capsule of the knee.

5.         Local Anesthetic Injection: The local anesthetic solution is infiltrated into this tissue plane, targeting the articular branches.

Advantages of the iPACK Block

The iPACK block offers several advantages:

●       Enhanced Analgesic Efficacy: It effectively anesthetizes the sensory nerves, providing targeted pain relief.

●       Reduced Opioid Consumption: It can reduce the need for opioids post-surgery.

●       Improved Functional Measures: Patients often experience improved functional outcomes.

●       Motor Function Preservation: It spares the main trunks of the tibial and common peroneal nerves.

●       Early Mobilization: By preserving motor function and reducing pain, it facilitates early mobilization.

Effectiveness of the iPACK Block

The iPACK block is effective in:

●       Pain Management: It significantly reduces pain scores.

●       Opioid Consumption: It is associated with reduced postoperative opioid consumption.

●       Functional Recovery: It tends to improve functional recovery and shorten hospital stays.

Recommended Surgical Procedures

The iPACK block is recommended for:

●       Total Knee Arthroplasty (TKA)

●       Cruciate Ligament Surgeries

●       Unicompartmental Knee Arthroplasty

Recent Studies on iPACK Blocks

Recent studies have focused on:

●       Analgesic Efficacy: Examining outcomes such as pain scores and morphine usage.

●       Comparison with Other Blocks: Looking into postoperative VAS scores and hospital stays.

●       Cadaver Studies: Demonstrating the spread of injection to the genicular nerves.

Comparison with Other Regional Anesthesia Techniques

The iPACK block compares favorably to other techniques like ACB, FNB, LIA, SNB, and TNB for its motor function preservation and targeted analgesia.

Potential Complications

Potential complications include:

●       Peroneal Nerve Block

●       Intravascular Injection

●       Vascular Injury

Despite these risks, the iPACK block remains a valuable tool for pain management when performed by skilled practitioners.

Current Studies

The current literature includes several studies on The Safety and Efficacy of the IPACK Block in Primary Total Knee Arthroplasty: A Retrospective Chart Review published in 2020 examined the safety and efficacy of the iPACK block in primary total knee arthroplasty (TKA), finding that patients who received the iPACK block had lower pain scores and improved ambulation distance.

In 2024 the review article IPACK Block Efficacy for Acute Pain Management after Total Knee Replacement: A Review highlighted that out of 7 clinical trials examined, 5 showed superior efficacy of the iPACK block combined with an adductor canal block (ACB) compared to other blocks.

Published in 2022, Analgesic Efficacy of Adding the IPACK Block to Multimodal Analgesia Protocol for Primary Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials mentioned that while the iPACK block has been adopted into clinical practice, its efficacy had not been confirmed by synthesized evidence at that time, indicating a need for more quantitative information to measure the certainty of evidence.

Additionally, Infiltration Between the Popliteal Artery and Capsule of the Knee (iPACK): Essential Anatomy, Technique, and Literature Review discusses how randomized controlled trials have shown that the iPACK block, when used in combination with a femoral nerve block (FNB) or ACB, is superior to FNB or ACB alone in controlling postoperative pain.

In summary, while there is a growing body of evidence supporting the efficacy of the iPACK block, ongoing research continues to contribute to our understanding of its role in multimodal pain management. The exact number of studies varies, but the trend indicates a positive outlook on the efficacy of the iPACK block in clinical settings.


Valkyrie Simulators and Workshops offer hands on learning and practice for more than 30 ultrasound guided nerve blocks. 


2.         IPACK Block Chapter 24 - NYSORA 

4.         iPACK Block: Infiltration in the Interspace Between Popliteal Artery and Capsule of the Knee

5.         The ultrasound-guided iPACK block with continuous adductor canal block for total knee arthroplasty

6.         The Safety and Efficacy of the IPACK Block in Primary Total Knee Arthroplasty: A Retrospective Chart Review

9.         Infiltration Between the Popliteal Artery and Capsule of the Knee (iPACK): Essential Anatomy, Technique, and Literature Review



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