Lumbar spinal stenosis is a common degenerative condition that can cause chronic low back and leg pain, especially during walking or standing. Interlaminar epidural steroid injections are widely used to relieve pain and improve function in patients who do not respond adequately to conservative treatments.

These injections are usually performed under fluoroscopic guidance, which allows accurate needle placement but exposes patients and healthcare providers to ionizing radiation. Ultrasound guidance has emerged as an alternative technique that avoids radiation exposure; however, ultrasound alone may not always confirm correct epidural spread of the injected medication.

This prospective, randomized clinical trial aims to compare two commonly used imaging approaches for interlaminar epidural steroid injections in patients with lumbar spinal stenosis: fluoroscopy-guided injection and ultrasound-guided injection with fluoroscopic confirmation (hybrid technique). The study will evaluate patient satisfaction, radiation exposure, procedure time, technical success, pain relief, and functional outcomes.

The results of this study are expected to help identify the most effective and safe imaging guidance method for interlaminar epidural steroid injections in patients with lumbar spinal stenosis.

This prospective, randomized clinical trial will compare two imaging guidance strategies for interlaminar epidural steroid injection in adult patients diagnosed with lumbar spinal stenosis. Eligible participants will be randomly allocated into two groups: a fluoroscopy-guided interlaminar epidural steroid injection group and an ultrasound-guided interlaminar epidural steroid injection group with fluoroscopic confirmation of epidural spread (hybrid technique).

All procedures will be performed at a single tertiary care center by experienced clinicians using standardized institutional protocols. In both groups, the interlaminar epidural space will be accessed using a midline or paramedian approach, and the same corticosteroid formulation and injection volume will be administered to ensure treatment consistency.

Procedural outcomes will include total procedure time, fluoroscopy time, radiation dose parameters recorded directly from the fluoroscopy unit, and technical success defined as correct epidural space access with appropriate contrast spread. Radiation exposure will be assessed using dose metrics provided by the imaging system, allowing comparison between the two guidance techniques.

Patient-reported outcomes will be evaluated using validated pain and functional assessment tools at baseline and during routine follow-up visits according to the study protocol. Patient satisfaction will be assessed following the procedure. Adverse events related to the procedure will be documented and monitored throughout the study period.

By systematically comparing these two imaging guidance approaches under standardized clinical conditions, this study aims to clarify whether ultrasound-guided interlaminar epidural steroid injection with fluoroscopic confirmation can reduce radiation exposure while maintaining procedural efficiency, technical accuracy, and clinical effectiveness comparable to conventional fluoroscopy-guided injection.

Inclusion Criteria:

• Age between 40 and 75 years
• Diagnosis of lumbar spinal stenosis confirmed by clinical evaluation and magnetic resonance imaging (MRI)
• Presence of neurogenic claudication symptoms for at least 3 months
• Inadequate response to conservative treatment, including medication, physical therapy, or exercise
• Numeric Rating Scale (NRS) pain score ≥ 4 at baseline
• Ability to provide written informed consent

Exclusion Criteria:

• Previous lumbar spine surgery
• Vertebral fracture, spinal malignancy, or history of significant lumbar trauma
• Peripheral vascular claudication or clinically significant peripheral polyneuropathy
• Epidural steroid injection within the past 6 months
• Medical conditions severely limiting ambulation unrelated to lumbar spinal stenosis (e.g., severe cardiopulmonary disease or advanced hip/knee osteoarthritis)
• Pregnancy or breastfeeding
• Coagulation disorders or inability to safely discontinue anticoagulant or antiplatelet therapy according to guideline recommendations
• Known allergy to local anesthetics, corticosteroids, or contrast agents
• Active local or systemic infection
• Body mass index (BMI) > 30 kg/m²

Individual participant data will not be shared publicly. De-identified aggregate data may be available upon reasonable request, subject to institutional policies and ethical approval.