Abstract / Summary
Introduction Low back pain (LBP) is the leading cause of disability worldwide, with approximately 90% of cases classified as non-specific low back pain (NSLBP) due to the absence of an identifiable underlying pathology. Despite extensive research to date, the biomechanical mechanisms contributing to NSLBP remain poorly understood, particularly the interaction between lumbar spine, sacroiliac joint (SIJ), and pelvic function. A proposed phenomenon, termed the Posterior Triangle Effect (PTE), describes the new concept of unilateral muscle imbalance, reduced lumbar, SIJ and pelvic range of motion (ROM), ipsilateral iliac crest elevation, and possible pain localised superior to the SIJ and lateral to the lumbar spine. However, the integration of these clinical features and the possibility of a PTE phenomenon is yet to be systematically investigated. Methods The authors will search the following electronic databases: PubMed/MEDLINE, SPORTDiscus, Scopus and EMBASE, with studies over the last decade (2016–2026). Two independent reviewers will screen titles, abstracts and full-text articles for eligibility using the Rayyan intelligent systematic review platform. Data from the included studies will be extracted using a researcher-developed data extraction form to capture the key characteristics of each study. The methodological quality of the included studies will be assessed using the Joanna Briggs Institute (JBI) Critical Appraisal Tools appropriate for each study design. The findings will be synthesised and presented using the PRISMA 2020 flow diagram, figures, tables and graphs. Ethics and dissemination: BM26/2/7. PROSPERO Registration Number: CRD420261419708.