Correlation Research Between Hounsfield Unit Value And BMD Of Lumber Vertebrae In Patients Undergoing MIS-TLIF Surgery And Its Prognostic Influence On The Utilization Of PMMA-PS

Objectives.1.To examine the relationship between bone mineral density values(BMD)and T values of cancellous bone of each lumber vertebral from L1-L4 measured by preoperative dual-energy X-ray absorptiometry(DXA)and the mean Hounsfield Unit values(HU value)of the sagittal cross-section at the level of each lumber vertebral bilaterally in patients who underwent minimally invasive transforaminal lumbar interbody fusion(MIS-TLIF)for lumber degenerative diseases.2.The HU values of the sagittal cross-sections of the L3-L5 vertebrae with or without polymethylmethacrylate augmented pedicle screws(PMMA-PS)were retrospectively examined to identify the critical bilateral sagittal HU values for which PMMA-PS are indicated.This allows for more precise intraoperative planning,which reduces the likelihood of screw loosening and other issues following surgery.Methods.1.Male patients aged between 50 and 70 years and postmenopausal female patients aged less than 70 years who were admitted to xxx spine surgery department from January 2021 to December 2022 with degenerative lumbar spine disease and treated with MIS-TLIF surgery by the same treating physician were selected as the total sample,excluding those with severe posterior hyperplastic calcification of the lumbar vertebral seen on lumbar spine CT.100 cases were chosen at randomly(84 of 100 were patients with CPS),and 30 cases were chosen independently for L3-L5 MIS-TLIF surgery with PMMA-PS.(1)100 patients were divided into four groups of L1-L4 vertebrae in order to examine the correlation between the BMD and T values of the cancellous bone of L1-L4 vertebrae as measured by the DXA method and the mean HU values of cancellous bone in the sagittal section at the level of each pedicle.(2)Among 100 patients,84 patients who did not use PMMA-PS were recorded as the non-cemented group and 30 patients were recorded as the cemented group,and the L3-L5 vertebrae were utilized to split the cemented and non-cemented groups into three groups in order to examine the predictive effect of HU values on the use of PMMA-PS.2.Before surgery,all patients got DXA and CT scans of the lumbar on the same machine.The nail placement path of each vertebra with the parallel "∧" shape crest as the nail entry point was used as the tangent line,and the sagittal section was tangent to the outer wall of the arch,the median line of the arch,and the outer wall of the arch,and the arbitrary ROI was utilized to measure the HU values of each section and calculate the average value.3.(1)Pearson test was used to verify the correlation between the measured HU value of each vertebra and the BMD value and T value measured by DXA examination,simple linear regression was used to test the correlation,and the HU value corresponding to the WHO diagnostic criteria(T ≧ 1,-1>T>-2.5,-2.5 ≦ T)was derived using the fitted equation.(2)The HU value of each L3-L5 vertebral in the cemented and uncemented groups was analyzed by the receiver operating characteristic curves(ROC),and the area under the curve(AUC)was derived.The HU values corresponding to the best cut-off value of each vertebral were chosen based on the Yordon index(YI),which is each critical HU value recommended for clinical use PMMA-PS.Results.(1)The average HU value of cancellous bone in the sagittal section at the level of the pedicle for each vertebral body from L1 to L4 was strongly connected with the BMD value and T value evaluated by DXA in 100 individuals.HU values of each vertebra were significantly and positively linked with BMD values and T values.BMD:L1(r~2=0.55 p < 0.001),L2(r~2 =0.66 p< 0.001),L3(r ~2=0.51 p< 0.001),L4(r ~2=0.68 p <0.001)).T: L1(r~2=0.71 p<0.001),L2(r~2= 0.75 p<0.001),L3(r~2=0.68 p<0.001),L4(r~2=0.71 p<0.001)(2)The HU values corresponding to the normal bone density group,the low bone mass group,and the osteoporosis group were calculated for each vertebra using the regression equation as follows: L1(HU Value≧119HU,119 HU > HU Value > 78 HU,HU Value≦78HU),L2(HU Value≧112HU,112 HU > HU Value> 74 HU,HU Value ≦74HU),L3(HU Value≥120HU,120HU>HU Value>72HU,HU Value≤72HU),L4(HU Value≥119HU,119HU>HU Value>81HU,HU Value≤81HU).2.Based on the HU value of the L3-L5 cement-reinforced and non-cement-reinforced groups,ROC curves were plotted,and the AUCs were all greater than 0.80,p0.05,indicating a high diagnostic significance.The optimal cut-off values for L3-L5 vertebrae corresponded to HU values of 78.5HU,74.2HU,and 81.5HU.Conclusion.In patients having MIS-TLIF surgery,the mean HU value of the sagittal cross-section generated by aiming the pedicle with a parallel "∧" shaped crest nailing path was measured by arbitrary ROIs:1.When the L1 vertebra is less than 78HU(77.11±8.51),the L2 vertebra is less than74HU(73.60 ± 6.91),the L3 vertebra is less than 72HU(71.28 ± 9.40),and the L4 vertebra is less than 81HU(80.79 ± 5.39),the patient should be considered to have osteoporosis and should be informed of the possibility of related complications and long-term regular anti-osteoporosis treatment.2.PMMA-PS is recommended when the L3-L5 vertebral is below 78.5HU,74.2HU,and 81.5HU,respectively,to reduce the risk of screw loosening after surgery.