前方アプローチによる人工関節置換術のためのPENGブロック＋LIA (PENG 360°)

Study Rationale Standard anesthetic techniques for hip fracture surgery in the target population, which often includes fragile and elderly individuals, present distinct challenges. Both neuraxial (spinal) and general anesthesia can have a significant hemodynamic impact. Furthermore, traditional regional anesthetic techniques like lumbar plexus or femoral nerve blocks, while providing effective analgesia, often result in significant motor and sensory blockade of the lower limb, which can impede early mobilization and rehabilitation.

This study investigates a motor-sparing anesthetic approach. The intervention is based on pericapsular nerve group blocks (A-PENG and PONG), anterior and posterior, which target only the sensory articular branches innervating the hip capsule. This technique, combined with local infiltration analgesia (LIA), aims to provide comprehensive surgical anesthesia and post-operative analgesia without affecting motor function, thereby facilitating immediate post-operative mobilization.

Anesthetic Intervention Details (PENG 360° Arm) Participants randomized to the investigational arm will receive a combination of three injections prior to surgical incision. A convex ultrasound probe will be used for A-PENG and PONG.

• Anterior A-PENG Block: An injection of 20 mL of "plain" anesthetic solution is administered into the fascial plane between the iliopsoas muscle and the hip joint capsule. This solution consists of 10 mL of 0.75% ropivacaine, 10 mL of 2% mepivacaine with 1:200,000 epinephrine, and 2 mg of dexamethasone.
• Local Infiltration Analgesia (LIA): An injection of 20 mL of "diluted" anesthetic solution is used to infiltrate the planned incision line and subcutaneous tissue. This solution consists of 5 mL of 0.75% ropivacaine, 5 mL of 2% mepivacaine with 1:200,000 epinephrine, 1 mg of dexamethasone, and 10 mL of normal saline.
• Posterior PONG Block: With the participant in the lateral decubitus position, an injection of 10 mL of "plain" anesthetic solution is administered into the fascial plane deep to the quadratus femoris muscle. This solution consists of 5 mL of 0.75% ropivacaine, 5 mL of 2% mepivacaine with 1:200,000 epinephrine, and 1 mg of dexamethasone.

During surgery, participants in this arm will receive supplemental oxygen and sedation with propofol, with the depth of anesthesia monitored using a Bispectral Index (BIS) monitor.

Post-operative Pain Management Protocol To ensure a standardized approach to analgesia for all participants in both study arms, a uniform post-operative pain management protocol will be implemented. Unless contraindicated, all participants will receive a fixed-dose regimen of intravenous paracetamol (1000 mg) and ketorolac (30 mg) every 8 hours.

In addition, all participants will be provided with an intravenous patient-controlled analgesia (PCA) pump delivering morphine. The PCA pump will be set to deliver on-demand rescue boluses of 2 mg of morphine with no continuous background infusion. The maximum daily dose will be limited to 10 mg for participants over 65 years of age and 20 mg for those 65 or younger.

Data Management and Randomization Participant data will be collected and managed using an electronic Case Report Form (CRF) built with Google Forms and stored in a secure cloud database (Google Sheets). All data will be pseudonymized using a unique alphanumeric identifier assigned at the time of enrollment to ensure participant confidentiality.

Randomization will be performed using a dedicated Google Form configured to provide response options in a random order. The investigator will select the first option presented to assign the participant to either the "case" or "control" group19.

Statistical Analysis Plan Descriptive statistics (mean, median, standard deviation, min/max) will be used to summarize the collected data. The primary endpoint (cumulative number of PCA rescue doses at 48 hours) will be analyzed using a Poisson distribution model.

For other outcomes, a Chi-square test will be used for categorical variables (e.g., need for conversion to general anesthesia), while a t-test (or a non-parametric equivalent) will be used for continuous variables (e.g., NRS pain scores in the recovery room). Analysis of covariance and multiple linear regression may also be conducted to evaluate the role of demographic and clinical characteristics on study outcomes.