Treatment Of Severe Osteoporotic Vertebral Fractures With Long-segment And Short-segment Fixation Of Screw Channel Augmentation Technique:Clinical And Finite Element Comparative Study

ObjectiveThe present study aimed to compare the clinical efficacy of long-segment and short-segment internal fixation with cement-enhanced pedicle screw in the treatment of patients with severe Osteoporotic Vertebral Fracture(sOVF),and to explore the distribution characteristics of TCM syndromes in patients with sOVF.Finally,the effects of two fixation methods on the stress of adjacent segments and fractured vertebrae were analyzed by finite element analysis.Method(1)Patients who diagnosed as sOVF were included in the study,and the TCM syndrome was diagnosed according to the standard of syndrome diagnosis.(2)A retrospective study of patients with single-segment sOVF treated with cement-enhanced pedicle screw fixation from January 1,2009 to January 1,2016 in the Spinal orthopedics of the First Affiliated Hospital of Guangzhou University of Chinese Medicine.The patients were divided into long-segment fixation group(LSF)and short-segment fixation group(SSF)according to the scope of the fixed segment.The visual analogue scale for pain(VAS),Oswestry disability index(ODI)and ASIA neurological grading were recorded.The Cobb angle and the fixed segment Cobb angle of the two groups were measured,and the correction rate of kyphosis and the loss rate of correction were calculated.In addition,we also recorded postoperative complications.(3)First,establishing T9-L5 segment model.Then simulating L1 vertebral fracture and establishing LSF and SSF models of cement-enhanced pedicle screw.The load and bending moment were applied vertically above the T9.By simulating flexion and extension of spine,the stress of the adjacent segments and the displacement of fractured vertebral body were analyzed.Result(1)A total of 45 patients with sOVF were included in the study of TCM syndromes distribution characteristics,38 cases were single segment fractures,and 7 cases were non-single segment fractures.According to syndrome differentiation,we found that 9 patients showed kidney yang deficiency syndrome,including 7 cases of blood stasis and qi stagnation syndrome.There were 23 patients of liver kidney yin deficiency syndrome,of which 18 cases with stagnation of blood stasis and qi stagnation syndrome.Finally,13 patients were manifested as spleen and kidney deficiency syndrome,of which 12 cases with blood stasis and qi stagnation syndrome.(2)There were 17 female patients in LSF with a mean age of(73.29±4.73)years.The average follow-up time was 39 months.There were 21 patients in SSF include 18 females and 3 males,with a mean age of(71.33±5.66)years.The average follow-up time was 42 months.Postoperative VAS and ODI were lower than before surgery in both groups(P<0.05),and there was no statistical difference between the two groups(P > 0.05).At the last follow-up,neurological function was improved in some patients(P<0.05),but there was no significant difference between the two groups(P>0.05).Postoperative kyphosis were corrected well in both groups,which was statistically significant compared with preoperative(P < 0.05),and there was no statistically significant difference in correction rate of kyphosis between the two groups(P>0.05).At the last follow-up,there was a certain correction loss in both groups,but the final Cobb angle in LSF was not statistically significant compared with the postoperative month(P>0.05).The leakage rates of bone cement in the SSF and LSF were 31% and 32%,respectively(P>0.05).Osteoporotic vertebral compression fractures occurred in 5 patients after LSF and the incidence was 29.41%.There were 6 patients with osteoporotic vertebral compression fractures in the SSF after operation and the incidence was 28.57%(P>0.05).(3)The finite element analysis indicated that the maximum stress values of T10 vertebral body and endplate in the two groups were similar.In LSF,L4 vertebral stress,L1 vertebral stress and displacement were all smaller than SSF.The stress of the pedicle screw mainly located at both ends,and the stress of the distal pedicle screw is greater.ConclusionMost of the patients with sOVF were based on liver kidney yin deficiency,followed by spleen and kidney deficiency and kidney yang deficiency.There was no significant difference in the stress between the two fixation methods for the proximal segment of the internal fixation.But LSF can reduce stress and displacement of fractured vertebral body.LSF and SSF with cement-enhanced pedicle screw can be used for the treatment of patients with sOVF.Long segmental fixation should be selected for patients who the fracture vertebral body cannot be inserted the pedicle screws,or with severe kyphosis or requiring osteotomy.