Total Periarticular Infiltration Vs Posterior Periarticular Infiltration Plus PENG Block for Hip Analgesia

In a recent study, direct periarticular local anesthetic infiltration (PAI) showed a greater incidence of early quadriceps weakness (33% at 3 hours and 13% at 6 hours) than pericapsular nerve group block (PENGB) in total hip arthroplasty (THA) but, in turn, demonstrated a statistically significant better pain control. Additionally, PENGB could not completely circumvent motor compromise either, particularly at 3 hours (20% incidence), probably secondary to an injectate migration towards the femoral nerve. Posteriorly to this publication, a cadaveric trial looking into the maximum effective volume that spared the femoral nerve resulted in 13.2 mL.

This newer evidence led to the design of a strategy that combines both interventions, aiming to obtain the best of them and have a solid alternative for those cases where very early mobilization is pursued.

Thus, it is hypothesized that posterior PAI added to a low-volume PENGB (10mL) represents a superior alternative to PAI in terms of strength preservation and provides effective analgesia during the first 24 postoperative hours after THA.

Patients who agree to participate in the protocol will be assigned to one group or another (PAI or posterior PAI+PENGB) through computationally generated block randomization. Outcome assessors blinded to randomization will perform all measurements.

All trial interventions (PAI or posterior PAI+PENGB) will be performed (or supervised) by one of the co-authors, an expert orthopedic surgeon anesthesiologist. Both interventions will be executed in the operating room, on the surgical table, under sedation, and with the barrier that separates the surgical field from the cranial area of the patient to keep the latter blind to the technique received.

All patients will undergo spinal anesthesia using 0.5% bupivacaine (10mg) plus 20 μg of fentanyl. Both groups will also receive tranexamic acid 1g intravenous (IV), ketoprofen 100mg IV, and acetaminophen 1gr IV. Propofol sedation guided with a targeted controlled infusion (TCI) model will be administered in order to obtain an adequate level of sedation.

All surgeries will be conducted by the same team of surgeons, performing a posterior approach technique in the lateral decubitus position.

In the recovery room, all patients will receive patient-controlled analgesia (morphine bolus = 1 mg; lockout interval = 8 minutes). On the surgical ward, all subjects will continue to receive acetaminophen (1 g per os every 6 hours), ketoprofen (100 mg per os every 8 hours) as well and patient-controlled analgesia (morphine bolus = 1 mg IV; lockout interval = 8 minutes).

Eligibility Criteria:
Inclusion Criteria:

* American Society of Anesthesiologists classification 1-3
* Body mass index between 20 and 35 (kg/m2)

Exclusion Criteria:

* Adults who are unable to give their own consent
* Pre-existing neuropathy (assessed by history and physical examination)
* Coagulopathy (assessed by history and physical examination and, if deemed clinically necessary, by blood work-up i.e. platelets ≤ 100, International Normalized Ratio ≥ 1.4 or prothrombin time ≥ 50)
* Renal failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work-up i.e. creatinine ≥ 100)
* Hepatic failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work-up i.e. transaminases ≥ 100)
* Allergy to local anesthetics (LAs) or morphine
* Pregnancy
* Prior surgery in the inguinal area corresponding surgical side
* Chronic pain syndromes requiring opioid intake at home