退行性脊柱矢状面失衡患者腰椎椎旁肌的特点及其与失平衡程度之间的关系

Characteristics of lumbar paravertebral muscle in degenerative sagittal imbalance and the association with the severity of sagittal deformity

目的:分析退行性脊柱矢状面失衡患者腰椎椎旁肌特点及其与脊柱矢状面失平衡之间的关系。方法:回顾性分析2017年1月~2020年9月收治的退行性脊柱矢状面失衡患者的临床资料。其中男49例,女71例,平均年龄70.5±9.2岁。采用站立位全脊柱X线侧位片评估患者矢状面的脊柱骨盆参数,包括C7矢状垂直轴(C7-SVA)、胸椎后凸角(TK)、腰椎前凸角(LL)、骨盆入射角(PI)、骨盆倾斜角(PT)及骶骨倾斜角(SS)。在轴向T2加权MRI上定量测量每例患者在各个腰椎节段对应的椎旁肌总面积(TCSA)及其相对横截面积(RtCSA),功能性横截面积(FCSA)及其相对横截面积(RCSA),各节段肌肉的脂肪浸润程度(FI%),椎旁肌的退变通过RCSA及FI%的数值来反映。分别根据年龄(中年组<65岁,老年组65~75岁,高龄组>75岁)及性别分组,比较各组之间的椎旁肌退变差异。另外,根据脊柱矢状面失平衡的严重程度,将120例患者分为两组:轻度失衡组患者89例(MI组,SVA 5~10cm)和重度失衡组31例(SI组,SVA>10cm)分析椎旁肌退变特点。采用多元线性回归分析腰椎椎旁肌退变与年龄、性别、体质指数(BMI)、失平衡严重程度之间的相关性。结果:女性患者椎旁肌的平均FI%显著高于男性患者,但男性的平均TCSA显著高于女性,两者差异均具有统计学意义(均P<0.05)。在不同年龄段的脊柱矢状面失衡患者中,三组患者从L1/2至L5/S1节段上椎旁肌退变参数FI%及RCSA均存在明显统计学差异(均P<0.05),其中高龄组患者退变程度最为明显,而对于参数RtCSA只在L1/2到L3/4节段上存在统计学差异。在不同严重程度的失衡患者中,重度失衡组在脊柱骨盆参数上拥有更小的PI、LL及TK值,而拥有更大的PI-LL,差异具有统计学差异(均P<0.05);在椎旁肌肉参数上,从L2/3到L5/S1节段上两组的RCSA具有统计学差异(均P<0.05),而两组参数TCSA之间只在L4/5和L5/S1节段有统计学差异(均P<0.05),两组椎旁肌的脂肪浸润率之间无统计学差异(均P>0.05)。椎旁肌肉退变参数(TCSA、FI%、RCSA)与年龄、性别、BMI及失衡严重程度之间的多元线性回归分析提示TCSA、FI%、RCSA与年龄、性别、BMI有关,而与矢状面失平衡严重程度(SVA)之间无线性相关。结论:在脊柱退变性矢状面失衡住院患者中,年龄、性别及BMI都与腰椎椎旁肌肉的退变有着一定的联系;尽管脊柱矢状面的失平衡程度(SVA)与椎旁肌退变之间无显著相关性,但是重度的脊柱矢状面失衡提示更加显著的椎旁肌退变。

Objectives:To investigate the characteristics of lumbar paravertebral muscles in patients with degenerative spinal sagittal imbalance and the association with the severity of sagittal imbalance.Methods:The clinical data of patients with degenerative spinalsagittal imbalance from January 2017 to September 2020 were retrospectively analyzed.There were 49 males and 71 females with an average age of 70.5±9.2 years.Standing full spine radiographs were used to assess patients′spinopelvic parameters in the sagittal plane,including C7 sagittal vertical axis(C7-SVA),thoracic kyphosis(TK),lumbar lordosis(LL),pelvic incidence(PI),pelvic tilt(PT)and sacral slope(SS).The total paravertebral muscle area(TCSA)and its relative CSA(RtCSA),the functional cross-sectional area(FCSA)and its relative cross-sectional area(RCSA),and the degree of fat infiltration(FI%)of the muscle at each level were quantified on axial T2-weighted MRI,and the total mean cross-sectional area and degree of fat infiltration were calculated for each patient(aveTCSA,aveRCSA and aveFI%).Differences in paravertebral muscle degeneration were compared between the groups according to age(adult group<65,old group 65-75,senior group>75 years old)and gender grouping respectively.In addition,120 patients were divided into two groups according to the severity of sagittal imbalance,with 89 patients in the mild imbalance group(MI group)(SVA 5-10cm)and 31 patients in the severe imbalance group(SI group)(SVA>10cm)to analyze the characteristics of paravertebral muscle degeneration.Multiple linear regression analysis was used to analyze the correlation between lumbar paravertebral muscle degeneration and age,gender,body mass index(BMI),and the severity of imbalance.Results:The aveFI%of the paravertebral muscles was significantly higher in female patients than in male patients,but the aveTCSA was significantly higher in male patients(all P<0.05).Among the three groups of patients with spinal sagittal plane imbalance of different age groups,there were significant differences in paraspinal muscle degeneration parameters(FI%and RCSA)from L1/2 to L5/S1 levels(all P<0.05),of which the senior age group was the most significant,while for RtCSA,there was only a significant difference at L1/2 to L3/4 levels.Among patients with different severity of imbalance,the severe imbalance group had smaller PI,LL and TK values and a larger PI-LL for spinopelvic parameters(all P<0.05);for paravertebral muscle parameters,RCSA was statistically different between the two groups at the L2/3 to L5/S1 levels(all P<0.05).There was a significant difference of TCSA between the two groups only at the L4/5 and L5/S1 segments(both P<0.05),and no significant difference in the FI%(both P>0.05).Multiple linear regression analysis showed that,aveTCSA,aveFI%,aveRCSA were associated with age,gender and BMI,while there was no linear correlation with the severity of sagittal imbalance(SVA).Conclusions:Age,gender and BMI were associated with lumbar paravertebral muscle degeneration in patients with spinal degenerative sagittal imbalance.Although there was no significant association between the degree of spinal sagittal imbalance(SVA)and paravertebral degeneration,severe spinal sagittal imbalance suggests more significant paravertebral degeneration.