Surgeon-Directed Arthroscopic Infiltration Between the Popliteal Artery and Capsule of the Knee (IPACK) Block: Technical Description

Abstract

Advances in regional anesthesia techniques for knee surgery have led to drastic improvements in postoperative pain control and have reduced reliance on perioperative opioid analgesics. The infiltration between the popliteal artery and capsule of the knee (IPACK) block has been a useful tool for providing posterior knee analgesia as an adjuvant to traditional femoral or adductor canal blocks in knee surgery. We present a simple and reproducible technique for the arthroscopic administration of this block.

Fig 1

In (A), the left knee is viewed from an anterolateral view. The left knee is placed in a 360° leg holder before being prepped and draped. In (B), the left knee is viewed from an anteromedial view after being prepped and draped. In both (A) and (B), the patella, tibial tubercle, and medial epicondyle are identified with a marker. In addition, the anticipated position for the posteromedial portal creation is also identified with marker.

Fig 2

In (A), from an anteromedial view, the left knee is visualized with the arthroscope viewing the posteromedial compartment through the intercondylar notch from a standard anterolateral portal. In (B), an arthroscopic view with 30° arthroscope visualizes an 18-gauge spinal needle introduced into the posteromedial compartment. The medial femoral condyle is identified in (B) on the left-hand side of the image and the posterior capsule (PC) can be seen on the far-right side of the image. In (C), in the arthroscopic view, the needle is directed toward the midline and used to pierce the posterior capsule for administration of the IPACK block. (IPACK, infiltration between the popliteal artery and capsule of the knee.)

Fig 3

From a posterior view, a cadaveric dissection of the posterior aspect of a left knee can be visualized following needle placement for IPACK block under arthroscopic control. The medial gastrocnemius muscle (labeled MG on the image) is retracted medially, and the lateral gastrocnemius (labeled LG on the image) and neurovascular bundle is retracted laterally (labeled NB on the image) exposing the posterior capsule (labeled C on the image). The needle tip, which can be viewed in the central portion of Figure 3, is noted to be correctly positioned within the retrocapsular space. (IPACK, infiltration between the popliteal artery and capsule of the knee.)

Fig 4

From a posterior view, in (A), the cadaveric posterior knee dissections performed following simulated IPACK block with methylene blue dye using ultrasound guidance can be visualized. In (B), the cadaveric posterior knee dissections performed following simulated IPACK block with methylene blue dye sing arthroscopic assistance can be visualized. Images in (A) and (B) demonstrate comparable staining patterns involving the posterior capsule and neurovascular bundle. (C, posterior capsule; IPACK, infiltration between the popliteal artery and capsule of the knee; NB, neurovascular bundle.)