Do Spino-pelvic Parameters Predict Development of Spondylolisthesis in Degenerative Disc Disease at the L4-5 Level.

Introduction: The natural history of degenerative disc disease (DDD) has been the subject of intense study over the last several decades. Although many authors have observed that the degenerated motion segment undergoes progressive reduction of mobility in all directions, in some instances, the degeneration progresses to a sagittal plane segmental displacement (degenerative listhesis).The aim of the study is to compare the spinopelvic parameters (SPPs) between patients with degenerated disc but no listhesis versus those who have a degenerative spondylolisthesis (DSL). We also attempt to statistically correlate and thereby predict which patients are likely to progress to DSL. Materials and Methods: Between September 2021 and August 2024, 63 patients with a single-level degenerative pathology at L4-5 level were divided into DSL and non-listhesis group. Their SPPs, namely pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), disc angle, and position of L5 were studied on standing lumbosacral spine X-ray. The variables were compared between groups, receiver operator characteristic and cut-off points were calculated, and a multiple logistic regression was performed. Results: 52 patients were available for final analysis. DSL groups had higher PI and PT as well as lower disc angle in comparison to non-listhetic patients. A PI of >48.8°, PT of > 16.75°, and a disc angle of >-8.05° (implying a more kyphotic segment) were deemed threshold values for predicting DSL. The logistic regression yielded an adjusted odds ratio of 1.127 (PI) and 1.299 (disc angle), respectively. Conclusion: High PI with pelvic retroflexion and normal LL seem to be the prerequisites for DSL developing at a degenerative disc at the L4-5 level. Thus, Roussouly Type 3 Spino-pelvic alignment individuals seem most predisposed to develop DSL.