椎旁肌萎缩及关节突关节形态改变与腰椎融合术后邻近节段疾病的相关性

Correlation between paraspinal muscle atrophy, morphological changes of facet joints and adjacent segment degeneration after lumbar fusion

目的探讨椎旁肌萎缩及关节突关节形态改变与腰椎融合术后邻近节段疾病(adjacent segment disease,ASDis)的相关性。方法对2014年1月至2020年12月因ASDis再次行后路腰椎融合术的195例患者进行回顾性分析,初次手术融合节段为L4,5的ASDis患者29例纳入研究(ASDis组)。按Roussouly分型,Ⅰ型5例、Ⅱ型9例、Ⅲ型10例、Ⅳ型5例。另选取同期腰椎融合术后未发生ASDis的患者29例作为对照组,根据性别、融合节段、腰椎Roussouly分型与ASDis组进行1∶1配对。通过CT和MRI测量并比较两组患者初次手术前后椎旁肌横截面积(cross-sectional area,CSA)、脂肪浸润度(fat infiltration,FI),初次术前关节突关节角(facet joint angle,F-J)及关节突关节椎弓根角(pedicle facet angle,P-F)。应用logistic回归分析确定腰椎后路融合术后ASDis发生的危险因素,并描绘受试者工作特征(receiver operating characteristic,ROC)曲线,计算曲线下面积及临界值。评估ASDis组患者再次手术前后的椎旁肌萎缩情况。结果58例患者随访时间为(59.25±6.38)个月(范围49~73个月)。ASDis组患者体质指数(body mass index,BMI)为(24.76±3.64)kg/m2,高于对照组的(22.24±2.92)kg/m2,差异有统计学意义(t=2.48,P=0.041);ASDis组椎旁肌CSA为(3214.32±421.15)mm2、相对横截面积(rCSA)为1.69±0.36,均小于对照组的(3978.91±459.87)mm2和2.26±0.29,差异有统计学意义(t=10.22,P=0.012;t=9.47,P=0.038);ASDis组椎旁肌FI为21.95%±5.89%,高于对照组的14.64%±7.11%(t=7.32,P=0.002);ASDis组F-J角为35.06°±3.45°,小于对照组的38.39°±4.67°(t=4.76,P=0.027);ASDis组P-F角为117.39°±8.13°,大于对照组的111.32°±4.78°(t=5.25,P=0.031)。多因素logistic回归分析显示较高的BMI(OR=1.34,P=0.038)、较小的椎旁肌rCSA(OR=0.02,P=0.017)及较高的椎旁肌FI(OR=1.58,P=0.032)是ASDis发生的危险因素。ROC曲线显示BMI曲线下面积为0.680,临界值为22.58 kg/m2;椎旁肌FI曲线下面积为0.716,临界值为15.69%;椎旁肌rCSA曲线下面积为0.227,临界值为1.92。ASDis组患者再次手术前椎旁肌与初次手术前相比,拥有较高的FI(25.47%±6.59%vs.21.95%±5.89%,t=3.99,P=0.042)及较小的rCSA(1.52±0.28vs.1.69±0.36,t=3.85,P=0.038);再次手术前椎旁肌FI与初次术前的差值与ASDis发生时间呈负相关(r=-0.53,P=0.039),rCSA差值与ASDis发生时间则呈正相关(r=0.64,P=0.043)。结论当BMI>22.58 kg/m2、椎旁肌FI>15.69%、椎旁肌rCSA<1.92,提示术后出现ASDis的可能性较大;初次手术后椎旁肌萎缩越明显,则ASDis可能发生越早。关节突关节形态学变化不能作为预测ASDis发生的指标。

Objective To investigate the correlation between paraspinal muscle atrophy,morphological changes of facet joints and adjacent segment disease(ASDis)after lumbar fusion operation.Methods A retrospective study was conducted among 195 patients who underwent posterior lumbar fusion again for ASDis at this institution from January 2014 to December 2020,including 29 patients with ASDis whose initial surgical fusion segment was L4,5.According to Roussouly's staging,there were 5 cases of type I,9 cases of type II,10 cases of type III,and 5 cases of type IV.Another 29 cases were selected from patients without ASDis after lumbar fusion as a control group.The control group was paired 1∶1 with the ASDis group according to gender,fusion segment,and Roussouly typing of the lumbar spine.The cross-sectional area(CSA)and fat infiltration(FI)of paravertebral muscle,facet joint angle(F-J)and pedicle facet(P-F)angle before the first(second)operation were measured and compared between the two groups.Then logistic regression analysis was used to determine the predictors of ASDis after posterior lumbar fusion.Finally,the receiver operation characteristic(ROC)curve was described,and the area under the curve(AUC)and cut-off point were calculated.At the same time,the paraspinal muscle atrophy before the second operation in ASDis group was measured.Results The average follow-up time of 98 patients was 59.25±6.38 months(range,49-73 months).The average body mass index(BMI)of ASDis group was 24.76±3.64 kg/m2,which was higher than that in control group(22.24±2.92 kg/m2)(t=2.481,P=0.041).The average CSA and relative cross-sectional area(rCSA)of paraspinal muscle in ASDis group were 3214.32±421.15 mm2 and 1.69±0.36 respectively,which were less than 3978.91±459.87 mm2 and 2.26±0.29 in control group(t=10.22,P=0.012;t=9.47,P=0.038).The FI degree of paraspinal muscle in ASDis group(21.95%±5.89%)was significantly higher than that in control group(14.64%±7.11%)(t=7.32,P=0.002).The F-J angle in ASDis group was 35.06°±3.45°,which was less than 38.39°±4.67°in control group(t=4.76,P=0.027).The P-F angle in ASDis group was 117.39°±8.13°,which was greater than 111.32°±4.78°in control group(t=5.25,P=0.031).Multivariate logistic regression analysis showed that higher BMI(OR=1.34,P=0.038),smaller rCSA of paraspinal muscle(OR=0.02,P=0.017)and higher FI of paraspinal muscle(OR=1.58,P=0.032)were the risk factors of postoperative ASDis.The ROC curve showed that the AUC of BMI was 0.680 and the cut-off point was 22.58 kg/m2;The AUC of the FI of paraspinal muscle was 0.716 and the cut-off point was 15.69%;The AUC of rCSA of paraspinal muscle was 0.227 and the cut-off point was 1.92.For ASDis patients,the paraspinal muscle before the second operation had a higher degree of FI(25.47%±6.59%vs.21.95%±5.89%,t=3.99,P=0.042)and a smaller rCSA(1.52±0.28 vs.1.69±0.36,t=3.85,P=0.038)than that before the first operation.The difference between the FI degree of paraspinal muscle before the second operation and the first operation was negatively correlated with the occurrence time of ASDis(r=-0.53,P=0.039),and the difference of rCSA was positively correlated with the occurrence time of ASDis(r=0.64,P=0.043).Conclusion When BMI>22.58 kg/m2,FI of paraspinal muscle>15.69%,and rCSA of paraspinal muscle<1.92,it suggests that ASDis is more likely to occur after operation.And the more obvious paraspinal muscle atrophy after the first operation,the earlier ASDis may occur.Morphological changes of facet joints cannot be used as an index to predict the occurrence of ASDis.