iPACK Block vs. Periarticular Infiltration for TKA Pain Control

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.

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.

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.