Transforaminal intradiscal steroid injection versus transforaminal epidural steroid injection for chronic discogenic low back pain with active discopathy: a randomized controlled trial protocol.

Introduction: Chronic discogenic low back pain (DLBP) with active discopathy (Modic type 1 changes) is a specific and debilitating phenotype. Transforaminal epidural steroid injection (TESI) and transforaminal intradiscal steroid injection (TISI) are commonly used treatments, yet their comparative efficacy remains uncertain due to a lack of high-quality, direct comparative studies. Objectives: To compare the clinical efficacy and safety of TISI versus TESI and to investigate whether the anatomical target of corticosteroid delivery (intradiscal vs. epidural) influences clinical and radiological outcomes in patients with chronic DLBP with active discopathy. Trial design: This is a single-center, prospective, parallel-group, assessor- and patient-blinded, randomized, controlled trial. Methods: A total of 118 eligible participants will be randomly allocated in a 1:1 ratio to receive either TISI or TESI. The primary outcome is the change in low back pain intensity from baseline to 1-month post-intervention, measured by the Numerical Rating Scale (NRS). Secondary outcomes, assessed at multiple time points up to 12 months, include longitudinal pain intensity (NRS), functional status (Oswestry Disability Index, Japanese Orthopaedic Association score), health-related quality of life (12-item Short Form Health Survey), psychological status (Hospital Anxiety and Depression Scale), radiological changes (Modic classification, intervertebral disc heigh and Pfirrmann grade), and the incidence of procedure-related adverse events. The primary analysis will follow the modified intention-to-treat principle, with longitudinal data analyzed using a linear mixed model. Discussion: This trial addresses a critical evidence gap by conducting a direct head-to-head comparison of two mechanistically distinct injection therapies. The findings are anticipated to significantly inform clinical practice and guide the development of evidence-based treatment algorithms for managing chronic low back pain with active discopathy. Ethics and dissemination: The study protocol has been approved by the Ethics Committee of Beijing Shijitan Hospital, Capital Medical University (IIT2024-032-003). Written informed consent will be obtained from all participants. The results of this trial will be submitted for publication in peer-reviewed journals and presented at scientific conferences, regardless of the outcome. Clinical trial registration: ChiCTR2500096006, https://www.chictr.org.cn/showproj.html?proj=249912.