Older patients with hip fractures often suffer from severe pain. Inadequate analgesia increases the risk of postoperative delirium, myocardial injury, and other complications. Peripheral nerve block is an important component of multimodal analgesia, but conventional local anesthetics (such as plain bupivacaine) provide only approximately 12 hours of analgesic duration, which is far from covering the most painful 72 hours after surgery. Liposomal bupivacaine has a slow-release property, prolonging the analgesic duration up to 72 hours after a single injection. However, its clinical advantages in hip fracture surgery remain controversial. The investigators suppose that, compared with plain bupivacaine alone, preoperative supra-inguinal fascia iliaca block using liposomal bupivacaine combined with plain bupivacaine can further improve analgesia, decrease opioid consumption, and improve postoperative recovery quality within 72 hours in older patients after hip fracture surgery.

Hip fracture is a global health concern. Data from 204 countries over the past 30 years show an increasing incidence of hip fractures in people over 55 years old. With population aging, China is projected to have 1.3 million new geriatric hip fracture cases annually by 2050, imposing a heavy burden on individuals, families, and healthcare systems. Timely surgery remains the preferred treatment.

Optimizing analgesia through multimodal strategies can enhance postoperative recovery and shorten hospital stays. Peripheral nerve blocks (PNB), particularly ultrasound-guided femoral nerve block or supra-inguinal fascia iliaca compartment block (FICB), have been shown to reduce pain and opioid consumption after hip surgery. A recent prospective cohort study indicated that better perioperative pain control with PNB is associated with lower opioid needs and shorter hospitalization.

Conventional local anesthetics like ropivacaine or bupivacaine provide analgesia for about 12 hours, which is insufficient for the entire perioperative period. Liposomal bupivacaine, an extended-release formulation, can provide analgesia for up to 72 hours. Some studies have demonstrated benefits of liposomal bupivacaine for nerve blocks in thoracic and hip surgeries, including improved recovery quality, reduced opioid use, and lower pain scores at 24-72 hours. However, evidence remains controversial; several meta-analyses suggest that while statistical differences exist, clinical relevance may be limited.

Inadequate pain control negatively affects postoperative outcomes and is associated with delirium, myocardial injury, and pulmonary complications-especially in vulnerable older patients with reduced physiological reserve and multiple comorbidities. Therefore, this randomized controlled trial aims to investigate whether preoperative FICB using liposomal bupivacaine combined with plain bupivacaine can provide superior perioperative analgesia compared with plain bupivacaine alone in older (≥55 years) patients undergoing hip fracture surgery.

Inclusion Criteria:

• Aged ≥ 55 years.
• Diagnosed as hip fracture and scheduled to undergo hip replacement surgery.
• Agree to receive regional nerve block and postoperative patient-controlled intravenous analgesia (PCIA).

Exclusion Criteria:

• Inability to communicate due to visual, auditory, language, or other reasons before surgery.
• Chronic opioid dependence and long-term use of various types of analgesics (for more than 3 months).
• Severe coagulation abnormalities (International Normalized Ratio > 1.7, activated partial thromboplastin time exceeding the normal value by more than 4 seconds, platelet count < 80 × 10⁹/L), trauma or infection at the intended puncture site, or severe low back pain.
• Preoperative severe renal insufficiency (serum creatinine > 442 μmol/L or requiring renal replacement therapy), hepatic insufficiency (Child-Pugh class C), or ASA physical status > IV.
• Known allergy to local anesthetics.
• Any other condition that the investigator or attending physician deems unsuitable for participation in the study.