The goal of this clinical trial is to learn if a new local anesthesia technique can control pain as well as the standard spinal anesthesia for adults having hip endoprosthesis surgery. The main questions it aims to answer are:

• Is the new local anesthesia technique as effective as standard spinal anesthesia in managing pain during the first two days after surgery?
• Does the new technique allow participants to move their leg sooner after the operation?

Researchers will compare the new local anesthesia technique (numbing medicine injected directly around the hip joint) to standard spinal anesthesia (a numbing injection in the back) to see if the new technique works just as well for pain control while possibly causing fewer side effects like nausea.

Participants who join this study will be randomly placed into one of two groups.

One group will receive the standard spinal anesthesia before their surgery.

The other group will receive the new local anesthesia technique before their surgery.

After the operation, researchers will track the amount of extra pain medicine each participant uses and will check their ability to move their hip, knee, and foot.

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.

Inclusion Criteria:

• Provision of signed and dated informed consent form.
• Scheduled for hip endoprosthesis surgery for femoral fracture with an anterior approach.
• Age 18 years or older.
• Willing and able to comply with the study protocol.

Exclusion Criteria:

• Failure to provide informed consent.
• Age less than 18 years.
• Known allergy to local anesthetics or other medications used in the protocol.
• Presence of infection at the planned injection site.
• Pre-existing hip prosthesis or prior major surgery on the same hip (e.g., revision surgery).
• ASA physical status class > IV.
• Administration of intraoperative opiates or conversion to general anesthesia.

Plan Description

Individual Participant Data (IPD) that will be shared:

The full, de-identified participant dataset.

The final study protocol.

The statistical analysis plan.

How to access the data:

Data will be available to qualified researchers for non-commercial, academic purposes upon reasonable request. Interested researchers should submit a formal proposal outlining their research goals to the Principal Investigator.

Data sharing timeline:

Data will be made available after the publication of the primary study results and will remain available for a period of 5 years.

Data will be made available starting 6 months after the publication of the primary manuscript. Data will remain available for a period of 5 years following publication.

Access to the de-identified individual participant data and supporting documents will be granted to qualified academic researchers for non-commercial purposes, such as secondary analysis or meta-analysis. Researchers must submit a formal research proposal to the Principal Investigator for review. A signed data sharing agreement will be required before data is transferred.