Current Anesthesiology Reports

, Volume 9, Issue 4, pp 474–478 | Cite as

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

  • Sanjay K. SinhaEmail author
  • Alexa Clement
  • Ann-Marie Surette
Regional Anesthesia (P Kukreja, Section Editor)
Part of the following topical collections:
  1. Regional Anesthesia


Purpose of Review

In this review, we discuss the essential iPACK (Infiltration between the Popliteal Artery and Capsule of the Knee) anatomy, block technique as well as potential complications, contraindications, and relevant literature evaluating the efficacy of the iPACK block.

Recent Findings

Recent literature supports the efficacy of the iPACK in controlling pain, improving postoperative physical therapy performance, and decreasing hospital length of stay (LOS). Cadaver studies have demonstrated that injection of dye in the tissue plane between the popliteal artery and the femoral shaft cranial to femoral condyles spreads to the genicular nerves that innervate the posterior knee and forms the basis of the analgesic mechanism of the iPACK. Randomized controlled trials have shown that the iPACK, when used in combination with a femoral nerve block (FNB) or adductor canal block (ACB), is superior to a FNB or ACB alone in controlling postoperative pain.


The iPACK controls posterior knee pain following total knee arthroplasty (TKA) by anesthetizing the articular branches from the sciatic and obturator nerves. This is a safe and relatively simple block to perform with a low risk of serious complications.


Infiltration of the interspace between the popliteal artery and the capsule of the knee iPACK Posterior knee anatomy Posterior knee analgesia Total knee arthroplasty analgesia 


Compliance with Ethical Standards

Conflict of Interest

Sanjay K. Sinha has received compensation from Pacira Pharmaceuticals for contributing to speaker’s bureaus and from Flexion Therapeutics for service as a consultant.

Alexa Clement declares that she has no conflict of interest.

Ann-Marie Surette declares that she has no conflict of interest.

Human and Animal Rights and Informed Consent

This article does not contain any studies with human or animal subjects performed by any of the authors.


Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance

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  9. 9.
    •• Niesen AD, Harris DJ, Johnson CS, Stoike DE, Smith HM, Jacob AK, et al. Interspace between Popliteal Artery and posterior Capsule of the Knee (IPACK) injectate spread: a cadaver study. J Ultrasound Med. 2018;00:1–5. cadaveric study examining the spread of colored latex during iPACK injections, suggesting a possible mechanism for the analgesic effect of this block. The potential for local anesthetic spread to the tibial and common peroneal nerves is also highlighted. CrossRefGoogle Scholar
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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  • Sanjay K. Sinha
    • 1
    Email author
  • Alexa Clement
    • 1
  • Ann-Marie Surette
    • 1
  1. 1.Department of AnesthesiologySt. Francis Hospital and Medical CenterHartfordUSA

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