Different spinal subtypes with varying characteristics of lumbar disc degeneration at specific level with age: a study based on an asymptomatic population

BACKGROUND: The relationship between spinal sagittal subtypes and lumbar disc degeneration is unclear. Thus, we aimed to investigate the relationship between lumbar intervertebral disc degeneration and age in asymptomatic healthy individuals with different sagittal alignments. METHODS: In this cross-sectional observational study, we examined 209 asymptomatic young and middle-aged volunteers (123 women and 86 men) who were divided into the following three groups according to age: groups A (20–30 years), B (31–40 years), and C (41–50 years). The volunteers underwent full-spine standing lateral radiography and magnetic resonance imaging (MRI, 3.0 T) of the lumbar spine. Based on panoramic radiography, two observers measured the spinopelvic parameters and classified the spine into Roussouly subtypes. The degree of disc degeneration was assessed based on T2-weighted images according to the Pfirrmann classification. RESULTS: There was a statistically significant difference in the degree of degeneration of type I spine between groups B and C at L4-L5 (P < 0.03) and L5-S1 (P < 0.01) and between groups A and C at L1-L2 (P < 0.04) and L4-L5 (P < 0.01). The degeneration degree of type II spine at all levels were significantly different between groups A and C. No statistically significant difference was found between groups A and B in all subtypes except for type II spine at L1-L2 (P < 0.04). A significant difference was found at four levels between groups B and C in type III spine (P < 0.05) and between groups A and C. For type IV spine, there was a significant difference in the degree of degeneration at L4-L5 (P < 0.02) between groups A and C. Moreover, almost all single parameters were not strongly correlated with the degree of disc degeneration. CONCLUSION: The different spinal subtypes have characteristics of lumbar disc degeneration at specific levels with age. We considered that spinal classification could be used as a predictor of lumbar disc degeneration. Our data may be helpful to increase awareness of the relationship between spinal subtypes and lumbar disc degeneration. LEVEL OF EVIDENCE: 3