Relationship Between Displacement Of The Psoas Major Muscle And Degenerative Spinal Deformity

ObjectivesTo analyze the difference of psoas major position between patients with degenerative spinal deformity(DSD)and people without spinal deformity,and to explore the correlation between psoas major position shift and structural changes of the spine.MethodsThe clinical and the imaging data of the 48 adult patients with DSD who visited the Department of Spinal Surgery in Shandong Provincial Hospital from April 2013 to January 2021 were collected,and 40 healthy adults were included which was considered as controls.The imaging data were mainly anterior and lateral X-ray of the spine which keep in the standing position,and the lumbar MRI.The parameters which were measured:(1)The sagittal parameters of spinal-pelvis:PI,PT,SS,LL;(2)The coronal plane parameters of spine:center of sacral vertical line-apical vertebrae(CSVL-AV),Cobb’s angle;(3)The parameters of displament of psoas major muscle:ventral displacement of psoas major muscle(VDPM),lateral displacement of psoas major muscle(LDPM);(4)The morphological parameters of psoas major muscle:anteroposterior diameter of psoas major muscle(ADPM),transverse diameter of psoas major muscle(TDPM),the fat infiltrates of psoas major muscle.Student-t test was used to pairwise comparisons.Pearson’s correlation test and Kendall’s correlation test was used for correlation analysis of each one.Differences were considered significant at P<0.05.Results1.General conditionsThere was no signal difference in the gender and age distribution between two groups(P>0.05).2.Comparion of spinal-pelvic parameters①The PI of DSD group was significantly larger than control group(53.8±12.8°,47.5±9.2°,respectively,P<0.01).②The PT of DSD group was significantly larger than control group(25.9±9.2°,18.0±7.2°,respectively,P<0.01).③There was no signal difference in SS between DSD group and control group(27.9±9.9°,29.5±9.0°,respectively,P>0.05).④The LL of DSD group was significantly smaller than control group(35.2± 16.2°,42.6±13.9°,respectively,P<0.05).⑤The Cobb’s angle of Scoliosis of DSD group was significantly larger than control group(14.9±13.0°,1.8±1.8°,respectively,P<0.01).⑥The CSVL-AV of DSD group was significantly greater than control group(15.45±15.8mm,1.2±1.2mm,respectively,P<0.01).3.Correlation analysis between the parameters of the displacement of the psoas major muscle and spinal-pelvic parameters①In DSD group,VDPM%correlated with PT(r=0.429,P<0.05),VDPM%correlated with PI(r=0.460,P<0.05),there was no important correlation between VDPM%and SS,LL,Cobb’s angle and CSVL-AV(P>0.05);In control group there were no clearly correlation between VDPM%and PT,PI,SS,LL,Cobb’s angle and CSVL-AV(P>0.05).②In DSD group,patients were grouped according to whether they had bilateral VDPM,there was significantly in Cobb’s angle and CSVL-AV between two groups(P<0.05);there was no significantly in PT,PI,SS and LL between two groups(P>0.05).In control group,patients were grouped according to whether they had bilateral VDPM,there was no signal difference in Cobb’s angle,CSVL-AV,PT,PI,SS and LL between two groups(P>0.05).③Among the LDPM patients in DSD group,the patients were grouped according to whether they had bilateral LDPM,and there was no signal difference in PT,PI,SS,LL,Cobb Angle and CSVL-AV between two groups(P>0.05).④In patients with VDPM in the DSD group,there was no significant correlation between the direction of the longer distance of VDPM and the direction of scoliosis(P>0.05),while in patients with LDPM,there were clearly correlation between direction of the longer distance of LDPM and the direction of scoliosis(P<0.05).4.Comparison of the morphological parameters of psoas major muscle.Correlation analysis between morphological parameters of psoas major muscle and spinal-pelvic parameters①The ADPM%of DSD group was significantly lesser than control group(0.95±0.16,1.09±0.17,respectively,P<0.01).②The TDPM%of DSD group was significantly lesser than control group(0.55±0.11,0.65±0.12,respectively,P<0.01).③The fat infiltrates of psoas major muscle of DSD group was significantly greater than control group(14.23±4.89%,10.13±5.89%,respectively,P<0.01).④In DSD group and control group,there was no signal correlation between ADPM%and PT,PI,SS,LL,Cobb’s angle and CSVL-AV(P>0.05).⑤In DSD group and control group,there was no signal correlation between TDPM%and PT,PI,SS,LL,Cobb’s angle and CSVL-AV(P>0.05).⑥In DSD group and control group,there was no signal correlation between fat infiltrates of psoas major muscle and PT,PI,SS,LL,Cobb’s angle and CSVL-AV(P>0.05).Conclusion1.The relationship between the changes of psoas major muscle position and the changes of spinal sequence in patients with DSD has been studied by us.When DSD occurs,sagittal and coronal parameters deteriorate,and the psoas major which attached to vertebral body is pulled.Because of the obvious degeneration of paravertebral muscles in patients with DSD,the attachment point of psoas major on the vertebral body is more likely to be destroyed,resulting in the ventral and lateral displacement of psoas major muscle.2.Degenerative spinal deformity group and the control group were visible psoas major ventral displacement,degenerative spinal deformity in patients with psoas major ventral displacement degree significantly correlated with sagittal parameters change,the control degree of psoas major ventral displacement has no obvious correlation with sagittal parameters change,prove that produced as a result of degenerative spinal sagittal plane deformity,psoas major ventral shift will happen.3.Lateral displacement of the psoas major muscle was observed only in patients with degenerative spinal deformity.The degree of lateral azimuth shift of the psoas major was significantly correlated with the changes in the parameters of the coronal plane of the spine,which proved that the psoas major was prone to lateral deviation when the coronal deformity occurred.4.In the DSD group,a significant correlation was observed between the occurrence of ventral psoas major deviation and changes in the coronal plane parameters,suggesting that the coronal plane degeneration of the spine has clearly influence on the ventral psoas major deviation.5.Anteropsoas major diameter,transverse diameter and fat infiltration degree in patients with degenerative spinal deformity group and control group had no significant correlation with spine-pelvis parameters,but there were signal differences between groups.It is suggested that the degree of paravertebral muscle degeneration in patients with degenerative spinal deformity is higher than that in healthy peers.