This study aims to compare the effects of a preemptive multimodal intravenous analgesia protocol and a femoral triangle block on early postoperative rehabilitation compliance in patients undergoing anterior cruciate ligament (ACL) reconstruction under general anesthesia. Adult patients aged 18 to 65 will be randomized to receive either multimodal intravenous analgesia or femoral triangle block prior to surgery. Rehabilitation compliance will be evaluated using the straight leg raise test, sit-to-stand success, and pain scores at multiple postoperative time points. Secondary outcomes include opioid consumption, incidence of opioid-related side effects.

Postoperative pain following anterior cruciate ligament (ACL) reconstruction is typically acute in nature and may hinder early physiotherapy interventions. Effective postoperative pain control is essential for optimizing rehabilitation outcomes by enabling early mobilization, which can reduce the risk of thromboembolic complications, maintain pulmonary function, and mitigate metabolic and endocrine stress responses. Adequate analgesia also helps prevent the development of chronic pain, supports cognitive function, and may shorten hospital stay.

ACL injuries are commonly observed in athletes, as well as middle-aged individuals engaging in recreational activities. The success of ACL reconstruction surgery is highly dependent on early and effective postoperative rehabilitation, particularly muscle strength restoration.

Delayed mobilization following surgery may lead to muscle atrophy, cartilage degeneration, and connective tissue adhesions. Early ambulation and rehabilitation are critical for tissue healing and for maintaining joint function and mobility.

Various methods have been utilized for postoperative analgesia, including patient-controlled epidural analgesia, intravenous patient-controlled analgesia (PCA), peripheral nerve blocks, and intra-articular local anesthetic infiltration. Multimodal analgesia protocols have demonstrated superior outcomes in terms of pain control, opioid-sparing effects, and patient satisfaction when compared with single-modality approaches.

This prospective, randomized, double-blind clinical trial will compare the effects of preemptive intravenous multimodal analgesia and femoral triangle block on early postoperative rehabilitation compliance in adult patients undergoing ACL reconstruction under general anesthesia. The interventions are routinely used in clinical practice and are recognized as safe and effective.

The primary objective is to evaluate whether either approach improves compliance with early rehabilitation tasks. Compliance will be assessed using functional recovery metrics including the straight leg raise test, sit-to-stand success, and patient-reported pain scores using the Numerical Rating Scale (NRS) at predefined postoperative time points.

Secondary endpoints include total opioid consumption, frequency of opioid-related adverse events (e.g., nausea, vomiting, itching), and overall patient satisfaction. This study addresses a current gap in the literature, as no previous trials have directly compared these two methods in this clinical context.

Inclusion Criteria:

Age: 18 years or older. Condition: Patients scheduled for anterior cruciate ligament (ACL) reconstruction surgery.

ASA Classification: Patients classified as ASA I, II, or III. Orientation: Patients who are fully oriented and can cooperate with study procedures.

Consent: Patients capable of providing informed consent to participate in the study.

Exclusion Criteria:

Informed Consent: Patients unable to provide informed consent. BMI: Patients with a BMI of ≥30 kg/m². Allergy: Known allergy to local anesthetics. Orientation and Cooperation: Patients who are not fully oriented or cannot cooperate with study procedures.

Additional Trauma: Patients with other traumatic injuries requiring opioid analgesia.

Neuropathic Pain History: Patients with a history of neuropathic pain. Chronic Pain Syndrome: Patients with a history of chronic pain syndrome.

The study will be double-blind, meaning neither the researchers nor the participants will know which treatment group they belong to, ensuring unbiased outcome assessment.