Correlation Between The Degree Of Lumbar Disc Degeneration,the Degeneration Of Paraspinal Muscles,and Serum Vitamin D Level

Objectives:To study the correlation between the degree of lumbar disc degeneration,the degeneration of paraspinal muscles,and serum vitamin D level;and to explore whether supplementation of calcitriol played a positive role in delaying intervertebral disc degeneration.Methods:Clinical retrospective study:A retrospective study was made on 150 middle to senior patients with diseases related to lumbar disc degeneration in our hospital,including 105 females and 45 males,aged 41～93（67.0 10.1）years.All patients underwent lumbar MRI examination and serum vitamin D level measurement.Pfirrmann classification standard was used to evaluated the degree of lumbar disc degeneration.According to Pfirrmann grade,lumbar disc degeneration was divided into normal,mild,moderate and severe degeneration.The standard cross-sectional area（SCSA）of paravertebral muscles（psoas,erector spinae and multifidus muscle）at L4/5 and L5/S1 segments were measured on T2 weighted MRI images.The degree of muscle fat infiltration was graded according to the Goutallier classification by evaluating the amount of fat infiltration.According to the clinical practice guidelines of Endocrinology Society,serum vitamin D can be divided into three levels:normal（≥30 ng/ml）,insufficiency（20-30ng/ml）and deficiency（<20 ng/ml）.The animal model experiment:Eighteen Sprague-Dawley rats were assigned into three groups,randomly:control group,degeneration group and treatment group.Rats in the degeneration group and treatment group were treated with acupuncture to make the model of caudal intervertebral disc degeneration.Two weeks after puncture,rats in the treatment group received calcitriol supplementation,while rats in the control group and degeneration group were supplemented with the same amount of normal saline.X-ray and MRI were performed on the caudal vertebra pre-puncture and 6-week post-puncture respectively.After 6 weeks of puncture,intervertebral disc specimens were gained,and hematoxylin-eosin staining,toluidine blue staining and safranin-O/fixation green staining were used to appraise the disc degeneration.Classification data was analyzed using rank sum test,quantitative data was analyzed using one-way ANOVA or Kruskal-Wallis test,and correlation analysis between variables was performed using Spearman correlation coefficient.Results:There were no patients with grade I,and the number of cases with grades Ⅱ to Ⅴ were as follows:L4/5,n=17,59,60 and 14;L5/S1,n=22,46,55 and 27.The SCSA of psoas,erector spinae and multifidus muscle in L4/5 segment were negatively correlated with the degree of lumbar disc degeneration（r=-0.294,-0.250 and-0.182）.The SCSA of psoas and multifidus muscle in L5/S1 segment is negatively correlated with the degree of lumbar disc degeneration（r=-0.344 and-0.346）.The stage of fat infiltration of the erector spinae and multifidus were correlated with the degree of lumbar disc degeneration（L4/5:r=0.174 and 0.188;L5/S1:r=0.193 and 0.283）.Compared with patients with normal intervertebral disc,the proportion of vitamin D deficiency in patients with lumbar intervertebral disc degeneration is higher.The level of fat infiltration in erector spinae and multifidus muscle is higher in patients with vitamin D insufficiency or deficiency,and the proportion of fat infiltration above moderate level（≥2 level）is more serious than that in patients with normal vitamin D.More than 98%of the psoas has no or only slight fat infiltration,which is hardly affected by the degree of lumbar disc degeneration and vitamin D level.A positive correlation exists between the lumbar disc Pfirrmann grade and age（L4/5:r=0.220;;L5/S1:r=0.221）;the degree of fat infiltration in the erector spinae and multifidus muscle were positively correlated with age（L4/5:erector spinae:r=0.426,multifidus:r=0.335;L5/S1:erector spinae:r=0.349,multifidus:r=0.370）.In the rat intervertebral disc degeneration model,the disc height index,Pfirrmann grade and histological score in the treatment group were more satisfied than those in the degeneration group（P<0.05）.Conclusions:The SCSA of paraspinal muscle decreases with the seriousness of lumbar disc degeneration,and the severity of fat infiltration of erector spinae and multifidus muscle is correlated with the degree of lumbar disc degeneration.Patients with more severe lumbar disc degeneration were more likely to have vitamin D deficiency.However,Patients with vitamin D deficiency may have more severe fat infiltration in the erector spinae and multifidus.Age is an important factor affecting the degeneration of lumbar intervertebral disc and paraspinal muscles.Supplementation of calcitriol may have a beneficial effect on postponing intervertebral disc degeneration in rats.