Degeneration Of Paravertebral Muscles In Degenerative Lumbar Scoliosis And Its Associated Factors Analysis

Objective: Degenerative lumbar scoliosis(DLS) has historically beensimply defined as a spinal deformity in a skeletally mature individual, with acurve measuring>10。in the coronal plain, according to the Cobb method. Ithas a complex cause, and a relative longer course and resulted in someunsymetry lesion in grandual advancement; DLS almost occur in thepopulation older than50, and the incidence is about6%-68%, which isincreasing gradually. These deformites often lead to low back pain, andradiculopathy owing to spinal stenosis, and severely affect the healty relatedquality of life of patients..Therefore, exploring its causes and formulating areasonable targeted treatment has become the target of the majority of spinesurgeons. Recently, almost experts and scholars have focused on its formationand development and so on, think that DLS is caused by asymmetric disc andfacet degeneration and the onset is marked by disc degeneration, and theprogression of scoliosis related to disc degeneration, intervertebral discasymmetry, bone density et al. But its pathomechanism has not been entirelyelucidated. Paravertebral muscles(PVM), first to provide stability to the spinalcolumn, and second to produce movements of the trunk; Last PVM, aseffector human torso posture reflex arc, related with spinal disorders, is veryclose. Nowadays, there are numerous previous studies about the associationsbetween structural changes in PVM and adolescent idiopathic scoliosis,congenital scolisis, kyphosis. But research about association between DLSand PVM is relatively little. We need use MRI to investigated thedegeneration of PVM in DLS, and analyse the relationship between PVMdegeneration in DLS and vertebral lateral translation, lumbar scoliosis Cobb’sangle, lumbar lordotic angle and apical vertebral rotation. To disclose the roleof PVM degeneration in the occurrence and progress of DLS, to provide some theory of prevention and treatment for DLSMethods: As a retrospective study,78patients with DLS withoutradiculopathy and78patients with lumbar degenerative diseases withoutradiculopathy and scoliosis were retrospectively enrolled from June2005toDecember2012as scoliosis group and control group. No significantdifferences were found in the gender, age and body mass index(BMI) betweenthe two groups. All the patients were voluntarily participate in this trial, andagreed to the obligation of the trail. All cases were performed X-ray and MRI.The percentage of fat infiltration area(%FIA) of the bilateral PVM at theL1-S1levels were measured using T2-weighted axial MRI and Image Jsoftware at the two groups. The specific methods were as follows: Firstly,mearsuring cross sectional area(CSA) of PVM: Three images were taken foreach of L1-S1disc levels and the center slice of them was chosen for thePVM evaluation, the CSA of PVM at every levels were measured byoutlining the regions of the muscle using the Image J software; Secondly,mearsuring FIA of PVM: The FIA was measured using a threshold technique,and in this technique, the fat tissue in the MR images were colored red, whichwere measured using the Image J software; Lastly, the%FIA relative to theCSA was calculated. The measured data were analyzed with a paired t-test, ifthere was significant difference between the both sides, its difference valuewas considered as asymmetry degree of PVM degeneration. The lumbarscoliosis Cobb’s angle, apical vertebral rotation and lateral vertebraltranslation were measured on frontal X-ray, and the lumbar lordotic angle wasmeasured on lateral X-ray in the DLS group. The correlation betweenasymmetry degree of PVM degeneration and vertebral lateral translation,lumbar scoliosis Cobb’s angle, lumbar lordotic angle, and apical vertebralrotation were analyzed in the DLS group.Results:1Scoliosis Group: the mean%FIA of the multifidus muscle on theconvex side were10.13%±5.37%,11.28%±7.18%,16.04%±9.90%,24.83%±11.64%,35.10%±14.45%and on the concave side were 15.44%±7.08%,22.37%±11.53%,26.48%±11.68%,37.07%±15.11,44.13%±17.91%at L1-2, L2-3, L3-4, L4-5and L5-S1levels, which showedsignificant differences between the convex side and the concave side(t=7.452,9.858,10.223,10.295,8.730; P<0.05), and the concave side was higher thanthe convex side at all levels. Asymmetric degree of multifidus muscledegeneration was10.08%±6.80%, which was positively correlated withlumbar scoliosis Cobb’s angle, vertebral lateral translation and apical vertebralrotation(0<r<1, P<0.05), but negatively correlated with lumbar lordoticangle(-1<r<0, P<0.05). Linear regression existed between lumbar scoliosisCobb’s angle as well as lumbar lordotic angle and asymmetric degree ofmultifidus muscle（F=80.762和6.658, P<0.05）.2Control Group: the mean%FIA of the multifidus muscle showed nosignificant differences between the left side and the right side at L1-2, L2-3,L3-4, L4-5and L5-S1levels（t=0.609,1.649,0.666,-1.256,-1.503; P>0.05）.Conclusion: There existed PVM asymmetric degeneration in DLS, whichhave potential clinical importance on the evaluation of curve progression, andmuscle degeneration is more often seen in the concave side; Its asymmetricdegree increased with progression of lumbar scoliosis Cobb’s angle, apicalvertebral rotation and vertebral lateral translation, and with decrease of lumbarlordotic angle.