Analysis Of Factors Of Formation And Development About Degenerative Lumbar Scoliosis

Objective :To investigate the influence on scoliosis angle of the asymmetric index of degenerative lumbar scoliosis, the degree of intervertebral disc degeneration and osteoporosis, and analyze the cause of the disease, supply theory base in the clinical use. Degenerative lumbar scoliosis has historically been simply defined as a spinal deformity in a skeletally mature with a Cobb angle of more than 10°in the coronal plain, which develops after skeletal maturity with a predominant lumbar location. However, recently, through a better understanding of biomechanics, spinal anatomy, and imaging techniques, it has been recognized that, in addition to the coronal imbalance, there is also an associated loss of sagittal balance and malrotation of the spine, which are integral components of the deformity. Degenerative lumbar scoliosis, therefore, represents a complex three-dimensional rotational deformity that affects the spine in the coronal, sagittal, and axial planes and thus treatment paradigms should be devised to address all three components of this disorder. The incidence of lumbar scoliosis is 2.5 % -15 % .The degeneration of intervertebral disk and intervertebral joint lead to lumbar scoliosis, the pathogenesis of degenerative lumbar scoliosis was ambiguous. Actually, degenerative changes, especially of the disc, vertebral body wedging, and facet joint arthrosis are responsible for the appearance of''de novo''scoliosis, especially the degeneration of intervertbral disc. Decreased bone density was initially considered to be the cause of degenerative scoliosis, but this has changed after finding that no significant difference exists in the bone density between patients with degenerative scoliosis of the adult. Whether the Compression fracture of the lumbar vertebra and the asymmetry of vertebra influence the development of degenerative lumbar scoliosis,it is a problem. We will discussion for the question in the article. Methods : As a retrospectively study,a total of 96 patients with degenerative lumbar scoliosis were retrospectively enrolled from January 2002 to August 2010 as scoliosis group, meanwhile 96 patents with lumbar spinal stenosis matched in gender, age and body mass index (BMI) were selected as control group. All patients were studies with plain radiographs, MRI and dual energy X-ray absorptiometry at presentation. Radiographic measurements include Cobb angle, the height of the convex and concave side of the apical disc and the contiguous disc superiorly and inferiorly, the height of the convex and concave side of the apical and the contiguous vertebral body superiorly and inferiorly in scoliosis group, the height of L2-3, L3-4, L4-5 discs and the height of L2-4 vertebral body in control group. The average relative signal intensity of lumbar intervertebral disc and cerebrospinal fluid in T2WI sagittal image was measured in apex intervertebral disc and adjacent discs by Adobe Photoshop 6.0 in scoliosis group, which was measured in L2-3, L3-4, L4-5 disc in control group. The bone density of lumbar, femoral neck, trochanter, and Ward,s triangle regions was measured with dual-energy x-ray absorptiometry, then calculate the average.Results:1 The average sum of disc height was 40.1±6.8 mm in convex side, 28.1±7.1 mm in concave side. there was significant difference in the average sum of disc height, in the average sum of disc height between two sides through paired t-test(P<0.001). The disc index was 0.63±0.07. The average sum of disc height was 36.1±4.2 mm and 36.6±3.9 mm respectively in control group. The paired t-test showed no significant difference between two sides (P= 0.4). The average sum of veatebrae height was 75.72±11.64mm in convex side, 71.94±9.62mm in concave side. There was significant difference between two sides through paired t-test (P=0.016). The veateral index was 0.95±0.021mm. The average sum of vertebrae height was 77.43±12.21 mm and 76.91±13.93mm respectively in control group. The paired t-test showed no significant difference between two sides (P<0.05)2 In scoliosis group, the grades of relative signal intensity of lumbar intervertebral disc and cerebrospinal fluid in T2WI sagittal image were as follows: gradeⅠin 10 , gradeⅡin 23, gradeⅢin 31,gradeⅣin 32. In control group, the grades of relative signal intensity of lumbar intervertebral disc and cerebrospinal fluid in T2WI sagittal image were as follows: gradeⅠin 23 cases,gradeⅡin 26,gradeⅢin 30,gradeⅣin 17.there was significant statistically difference in the degenerative degree of intervertebral discs between two groups(P<0.05).3 The average T-value of various areas is -3.4±1.9, and the rate of osteoporosis is 74.0% in scoliosis group. The average T-value of various areas is -2.3±1.6, and the rate of osteoporosis is 31.3% in control group. There was significant statistically difference of the average T-value and the rate of osteoporosis between two groups (P<0.05).4 Multiple linear regression analysis showed that the asymmetric disc index, the degenerative degree of intervertebral disc and osteoporosis were the predominant correlative factors, which affect the development of degenerative lumbar scoliosis. The standardized partial regression coefficient are 0.328,0.062,0.099 respectively.Conclusion: Degenerative lumbar scoliosis is always accompanied by the height asymmetry of intervertebral discs from convex and concavity sides. The worse the degenerative degree of intervertebral disc is, the higher the rate of osteoporosis is. The positive correlation was testified among the angle of scoliosis, the asymmetric disc index, the degeneration of intervertebral disc and the bone density (T-value). The asymmetric disc index causes the strongest effect on the angle of scoliosis.