Please confirm that an ethics committee approval has been applied for or granted: Yes: I’m uploading the Ethics Committee Approval as a PDF file with this abstract submission

Background and Aims Ankylosing spondylitis (AS), a persistent inflammatory condition targeting sacroiliac joints and spine, induces stiffness and a distinctive bamboo spine, presenting challenges in anesthetic management due to airway complexity and spinal rigidity. The aim of this is to determine whether an ultrasound-assisted technique could reduce the number of needle passes required for a successful dural puncture in patients with abnormal spinal anatomy compared with conventional landmark-guided techniques

Methods This prospective randomized controlled comparative study will be conducted in cooperative patients aged between 18 and 60 years of either sex, belonging to American Society of Anaesthesiologists physical status I and II, scheduled to undergo elective total hip replacement under spinal anesthesia. Patients were randomly assigned to two groups via a computer-generated random table: Group 1 received ultrasound-guided subarachnoid blocks, and Group 2 received blocks using the surface landmark technique After taking sterile precautions, the puncture site was prepared, and the subarachnoid block was administered using the assigned method. Hemodynamic variables such as heart rate, mean arterial pressure, SpO2, and ECG readings were continuously monitored, along with the total number of attempts taken to administer the block.

Results In Group I using the USG method, most participants achieved block success on the first attempt, whereas Group II using the landmark technique had a lower first-attempt success rate, resulting in a significant difference. The USG method marginally increased procedure time, though not significantly.

Conclusions The preprocedural ultrasound-assisted sub arachnoid block can increase the first-pass success rate in patients of ankylosing spondylitis undergoing total hip replacement surgery