Correlation analysis of lumbar disc degeneration characteristics and bone mineral density in patients with osteoporosis based on the Roussouly classification.

Abstract

Background: Lumbar disc degeneration (LDD), endplate damage, and osteoporosis (OP) are closely linked; however, research on the influence of sagittal alignment on bone mineral density (BMD) and LDD is limited. This study aimed to explore the relationship between BMD, degenerative changes in intervertebral discs (IVDs), and endplate damage in patients with OP based on the Roussouly classification.

Methods: This retrospective study included 150 patients with and 150 without OP. Dual-energy X-ray absorptiometry (DXA) measured L1-4 vertebral BMD. Magnetic resonance imaging (MRI) assessed Pfirrmann grading (as a marker for disc dehydration status) and grading of endplate damage in the L1-S1 segments. The vertebral osteophyte score was evaluated. IVD degeneration and endplate damage were compared between groups and correlated with BMD. Patients were divided into four subgroups according to the Roussouly classification (based on different sagittal morphologies of spinopelvic anatomy) for further analysis.

Results: The Pfirrmann scores and endplate damage scores of the OP group at L1/2-L5/S1 were significantly higher than those of the control group (P<0.001). A negative correlation was observed between BMD and both Pfirrmann scores and endplate damage scores in the OP group (P<0.05). In the control group, no significant differences were observed in BMD and lumbar IVD parameters at L1/2-L5/S1 among the four patient subtypes. In the OP group, type II patients had the lowest BMD. Type I and II patients exhibited significantly greater disc dehydration and greater endplate damage sat L1/2-L5/S1 than type III and IV patients (P<0.05), with type II experiencing severe degeneration. Similarly, at the L4/5 and L5/S1 segments, type I and II patients demonstrated significantly greater disc dehydration and endplate damage compared to the type IV patients. Furthermore, type II patients showed more pronounced disc dehydration and endplate damage than type III patients. The correlation between BMD and IVD parameters was stronger in type I and II patients than in type III (P<0.05), with type II showing the strongest correlation. No significant correlation was found in type IV patients.

Conclusions: Patients with OP exhibited higher degrees of lumbar disc dehydration and endplate damage than the control group. A negative correlation was observed between BMD and the extent of lumbar disc dehydration, as well as endplate damage. Type II patients exhibited the lowest BMD. Types I and II displayed significantly greater LDD and endplate damage than types III and IV, with type II experiencing more severe degeneration than type I.