A study of the factors associated with cervical spinal disc degeneration, with a focus on bone metabolism and amino acids, in the Japanese population: a cross sectional study

Abstract

Background: The physical and biochemical factors responsible for cervical disc degeneration, and resulting in various spinal disorders, remain unclear. This study aimed to evaluate the correlation between cervical spinal canal stenosis and degeneration of intervertebral discs, and to analyze the factors related to disc degeneration in the Japanese population.

Methods: Three hundred and forty-four Japanese general residents underwent investigations, including magnetic resonance imaging of the cervical spine, in our health check project. We measured anteroposterior diameters at the levels of the cervical spinal disc in mid sagittal plane magnetic resonance imaging and evaluated disc degeneration. Spearman correlation coefficient was used to evaluate whether the diameters were correlated with disc degenerative scores. Stepwise multiple linear regression analysis was conducted with the score of disc degeneration as the dependent variable; and age, physical measurement values, bone mineral density of the forearm, and the value of serum bone metabolic markers and amino acids as the independent variables for each sex.

Results: As the age increased, the anteroposterior diameters decreased in both sexes. The minimum anteroposterior diameters were correlated with the disc degenerative scores (Spearman r = - 0.59, p < 0.001 in men, Spearman r = - 0.53, p < 0.001 in women). In multiple linear regression analysis, age, cross-linked N-telopeptide of type 1 collagen and isoleucine were significantly correlated with the cervical disc degenerative score in men (R² = 0.47), and age and lysine were significantly correlated with the degenerative score in women (R² = 0.50).

Conclusion: The factors responsible for cervical disc degeneration differed between men and women. Whether modifying these significant factors is possible, or whether this intervention would contribute to prevention of disc degeneration requires future studies.

Keywords: Amino acid; Bone metabolism; Cervical spine; Disc degeneration.

Fig. 1

Evaluation of severity score of cervical spondylosis. Intervertebral disc degeneration was evaluated based on the following two magnetic resonance findings: (1) decrease in the signal intensity of the intervertebral discs, and (2) disc space narrowing. The cervical intervertebral levels evaluated for disc degeneration included all levels from C3/4 to C7/T1. To rate the magnetic resonance findings, we used Matsumoto’s classification [Matsumoto M, JBJS-Br 1998]

Fig. 2

Measurement of the diameter on mid-sagittal magnetic resonance imaging. Minimum anterior-posterior diameter on mid-sagittal magnetic resonance imaging / anterior-posterior diameter of C3 vertebral body was calculated by dividing B by A as illustrated in this figure. A is the anterior-posterior diameter of C3 vertebral body, B is the minimum anterior-posterior diameter of spinal canal from C3/4 to C7/T1

Fig. 3

Bar chart (mean and standard deviation) showing the % anterior-posterior diameter by age at each level and minimum % anterior-posterior diameter in men. A/P: anterior-posterior, HSD: honestly significant difference

Fig. 4

Bar chart (mean and standard deviation) showing the % anterior-posterior diameter by age at each level and minimum % anterior-posterior diameter in women. A/P: anterior-posterior, HSD: honestly significant difference

Fig. 5

Bar chart (mean and standard deviation) showing disc degenerative score by age at each level and sum of score in men. HSD: honestly significant difference

Fig. 6

Bar chart showing (mean and standard deviation) the disc degenerative score by age at each level and sum of score in women. HSD: honestly significant difference

Fig. 7

Scatter plot showing the correlation between age and cross-linked N-telopeptide of type 1 collagen in men. NTX: cross-linked N-telopeptide of type 1 collagen