In this study, patients are allocated to the intervention and control groups using block randomization. The unit of randomization is the individual participant, and all eligible patients enter the randomization process after confirmation of the inclusion criteria and obtaining written informed consent. Simple randomization or quasi-randomized methods are not used in this study.
Randomization is performed using equal-sized blocks with a block size of 4 and an allocation ratio of 1:1 between the intervention and control groups. Stratified randomization is not applied in this study. The random allocation sequence is generated independently prior to study initiation using validated online random number generation tools (www.randomization.com or www.randomizer.org). The generated sequence, which defines the order of assignment to the two groups, is not accessible to the study execution team or outcome assessors.To ensure allocation concealment, each participant’s group assignment is recorded on a separate sheet and placed inside sequentially used, opaque, sealed envelopes labeled with a unique four-character code. Envelopes are opened in order and only after definitive enrollment of the participant and completion of all inclusion criteria, by the designated study executor. Participants, the clinical care team, researchers, outcome assessors, and data collectors are blinded to group allocation and type of intervention, thereby minimizing the risk of bias in treatment assignment and outcome assessment.
In this randomized clinical trial, blinding is implemented to minimize allocation, performance, and assessment bias throughout the study. After receiving a full explanation of the study objectives and providing written informed consent, participants are enrolled in the trial; however, due to the use of general anesthesia and identical procedural steps in both groups, they remain unaware of the type of intervention allocated to them. Clinical care providers, including surgeons, anesthesiologists responsible for general anesthesia, operating room staff, ward nurses, and postoperative care personnel, are blinded to group allocation. To maintain blinding at the anesthesiology level, the erector spinae muscle block is performed by an experienced anesthesiologist who is a member of the research team but does not participate in general anesthesia management, intraoperative care, postoperative care, or outcome assessment. A second anesthesiologist, who is responsible for administering general anesthesia, is not informed about whether the block has been performed or which solution has been injected. In both the intervention and control groups, all preparation procedures, injection sites, and surgical dressings are standardized and identical, ensuring that no visible differences can reveal the assigned intervention. This approach prevents unintentional unblinding of patients and clinical staff. The principal investigator, co‑investigators, research assistants, and outcome assessors are blinded to the treatment allocation and have no access to the randomization sequence. Outcome measures, including postoperative pain intensity assessed by the Visual Analogue Scale, opioid consumption, time to first request for analgesia, and functional outcomes, are collected by trained personnel who are unaware of group assignment. All collected data are analyzed using coded group labels, and the data analyst remains blinded to the intervention type until the final analysis is completed. No independent Data Safety and Monitoring Committee is defined for this study due to its limited scale and low‑risk nature.