IPACK vs Adductor Magnus Plane Block Added to Adductor Canal Block for Total Knee Arthroplasty

Summary

Total knee arthroplasty (TKA) is among the most frequently performed surgical procedures for degenerative joint diseases, including advanced knee osteoarthritis, rheumatoid arthritis, and post-traumatic arthritis. More than 700,000 TKA procedures are performed annually in the United States alone since 2012, with projections estimating a 143% increase by 2050. A significant proportion of patients experience moderate to severe postoperative pain following the procedure, adversely affecting early mobilization, adherence to rehabilitation programs, and ultimately functional recovery .

Femoral nerve block (FNB) was historically the cornerstone of TKA analgesia; however, concerns about quadriceps weakness and associated fall risk led to its replacement by more motor-sparing alternatives . Adductor canal block (ACB) has since become the standard approach, providing analgesia equivalent to FNB while significantly preserving quadriceps strength . Nevertheless, ACB does not adequately cover the posterior capsule and popliteal plexus terminals; consequently, 60-80% of TKA patients report significant posterior knee pain that cannot be sufficiently managed by ACB alone .

To address this limitation, several posterior knee analgesia techniques have been described. The IPACK (Interspace between Popliteal Artery and Capsule of the Knee) block targets genicular nerve branches and popliteal plexus terminals by injecting local anesthetic between the popliteal artery and the posterior knee capsule, largely sparing the main motor trunks and providing selective posterior analgesia . The adductor magnus muscle plane (AMM) block is a relatively novel interfascial plane block technique applicable in the supine position simultaneously with ACB. By injecting local anesthetic into the fascial plane along the posterior surface of the adductor magnus muscle, the AMM block aims to spread to the popliteal plexus and posterior capsular branches, potentially mimicking a sciatic nerve block effect . A key advantage of the AMM block is its applicability without patient repositioning during the same session as ACB.

The primary objective of this prospective randomized trial was to compare the effects of IPACK and AMM blocks-both added to ACB-on postoperative opioid consumption in patients undergoing TKA. Secondary objectives included evaluating the impact of each technique on postoperative pain scores, mobilization time, functional recovery, and motor function

Conditions

• Total Knee Anthroplasty
• Knee Osteoarthritis
• Postoperative Pain Management

Interventions

PROCEDURE

ACB+IPACK

With the patients in the supine position and the knee slightly externally rotated, the ultrasound transducer will be placed transversely on the medial aspect of the knee, approximately 2-3 cm above the patella. After identifying the distal femoral shaft and the popliteal artery, the needle will be advanced in-plane in an anteromedial direction toward the space between the popliteal artery and the femur. Following negative aspiration and confirmation with normal saline, 10 mL of 0.5% bupivacaine and 10 mL of 0.9% NaCl will be administered, with aspiration performed every 5 mL. Needle tip visibility, needle shaft visibility, number of needle insertions, and block duration will be recorded for all procedures. Dermatomal spread of the tibial, peroneal, sural, saphenous, and posterior femoral cutaneous nerves (PFCN) will be assessed at predefined time points: 5, 10, 15, 20, 30, and 45 minutes after block administration.

PROCEDURE

ACB+AMM

With patients supine and the leg slightly abducted and externally rotated, the ultrasound probe will be placed 10-15 cm distal to the inguinal crease and moved medially to visualize the adductor muscles. The needle will be advanced in-plane from anteromedial to posterolateral, avoiding the femoral vessels and obturator nerve, until a fascial "pop" indicates entry into the posterior compartment. After negative aspiration and saline confirmation, 10 mL of 0.5% bupivacaine and 10 mL of 0.9% NaCl will be injected. In the AMM group, the adductor canal block will be performed by redirecting the same needle without a second puncture; in the IPACK group, a separate insertion will be used. Dermatomal spread will be assessed at 5, 10, 15, 20, 30, and 45 minutes after block administration.

Sponsors & Collaborators

• Ataturk University

  lead OTHER

Principal Investigators

• Ahmet Murat Yayık · [email protected]

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

75 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2023-10-10

Primary Completion

2024-01-10

Completion

2026-02-06

Countries

• Turkey (Türkiye)

Study Locations