Spinal anesthesia is frequently administered using the conventional landmark technique. Ultrasound is a non-invasive and safe approach. Neuroaxial anesthesia procedures can be conducted using two different ultrasound techniques; Real-Time Ultrasound Guided (USRTG) and Ultrasound-Assisted (USAS). The primary objective of this study is to compare the successes of spinal anesthesia applications using USRTG, USAS, and conventional landmark techniques on the first attempt in obese patients undergoing orthopedic surgery.

Patients included in the study will be those undergoing lower extremity orthopedic surgery, with a body mass index (BMI) 30 kg/m² and above, and classified as American Society of Anesthesiologists (ASA) class I-III. Patients will be randomized into 3 groups. In the Conventional Landmark group, spinal anesthesia will be administered using the conventional technique. In the Ultrasound-Assisted group, the spinal space will be marked with ultrasound before proceeding. For the Real-Time Ultrasound-Guided group, the spinal space and the advancement of the needle for the injection will be visualized simultaneously with ultrasound during the application of spinal anesthesia. The primary outcome is to compare the success rates on the first attempt. The secondary outcomes are to compare the number of skin punctures, needle redirections, procedure times, complications, and patient satisfaction

Inclusion Criteria:

• 18 years and older
• Patients who will undergo lower extremity orthopedic surgery
• ASA I-II-III patients
• BMI 30 kg/m² and above

Exclusion Criteria:

• BMI < 30 kg/m²
• ASA IV-V patients
• Severe cardiovascular disease
• Patients with a known or suspected allergy to local anesthetics
• Contraindications of spinal anesthesia (eg, coagulopathy, puncture site infection)