| Objective1.To investigate the incidence of non-operative vertebral refractures(including adjacent vertebral fractures and distant vertebral fractures)after single-segment percutaneous augmentation(PVA)and related influencing factors.2.The relevant influencing factors of bone bridge formation in front of injured vertebrae after PVA surgery were analyzed,the imaging characteristics of bone bridge formation in front of injured vertebrae were summarized,and the causes of bone bridge formation were discussed in combination with the concept of "stability differentiation and treatment"proposed by the orthopedics department of traditional Chinese medicine.3.Based on the concept of "stability differentiation and treatment" and modern advanced imaging technology,three-dimensional finite element analysis was applied to analyze the influence of bone bridge formation in front of injured vertebrae and the change of injured vertebrae height on the stress of adjacent vertebrae after PVA surgery.MethodsPart 1 Clinical study:The clinical data of patients with single-level thoracic and lumbar OVCFs who received PVA treatment at the First Affiliated Hospital of Guangzhou University of Chinese Medicine and the Third Affiliated Hospital of Guangzhou University of Chinese Medicine from January 2014 to January 2022 were retrospectively analyzed.According to the inclusion criteria and exclusion criteria,486 patients were included and divided into postoperative recurrent fracture group and postoperative non-fracture group.The segments of the fractured vertebrae,the degree of compression of the vertebrae,the shape of the vertebrae,the type and distribution of the fractured area,the injury of the upper and lower endplates of the vertebrae,the degree of degeneration of the adjacent discs in the upper and lower extremities,the degree of degeneration of the paravertebral muscles,the injury of the posterior ligament complex,the bone mineral density T-value of the lumbar spine or hip,the VAS score,and the vertebrae were compared Cobb Angle,anterior vertebral edge height,anterior vertebral edge height recovery rate of injured vertebrae,type of bone cement distribution and amount of bone cement,disc leakage of bone cement,location and time of postoperative recurrent vertebral fractures,recollapse of cemented vertebrae,and whether bone bridges were formed between strengthened vertebrae and adjacent vertebrae.Part 2 Clinical study:The clinical data of patients with single-level thoracolumbar OVCFs who received PVA treatment at the First Affiliated Hospital of Guangzhou University of Chinese Medicine and the Third Affiliated Hospital of Guangzhou University of Chinese Medicine from January 2014 to January 2022 were retrospectively analyzed.According to the inclusion and exclusion criteria,486 patients were included and divided into postoperative injured vertebrae without bone bridge group and postoperative injured vertebrae fracture group.The segments of the fractured vertebrae,the degree of compression of the vertebrae,the shape of the vertebrae,the type and distribution of the fractured area,the injury of the upper and lower endplates of the vertebrae,the degree of degeneration of the adjacent discs in the upper and lower extremities,the degree of degeneration of the paravertebral muscles,the injury of the posterior ligament complex,the bone mineral density T-value of the lumbar spine or hip,the VAS score,and the vertebrae were compared Cobb Angle,anterior vertebral edge height,anterior vertebral edge height recovery rate of injured vertebrae,type of bone cement distribution and amount of bone cement,disc leakage of bone cement,location and time of postoperative recurrent vertebral fractures,re-loss of reinforced vertebral height,and whether bone Bridges were formed between strengthened vertebrae and adjacent vertebrae.Part 3 Finite element study selected the thoracolumbar CT scan data of a normal male volunteer,compressed the anterior margin of the T12 vertebra into three states of mild(25%),moderate(40%),and severe(70%),and constructed the bone cement simulation within the injured vertebra,and established the finite element model of the vertebra compression of T10-L2 complete osteoporosis with different degrees.Finally,8 groups of models were simulated with or without anterior bone bridge after PVA operation.After testing the rationality,physiological activities such as spinal forward flexion,backward extension,left and right lateral curvature and left and right rotation were simulated on each model,and the difference of Von Mises stress extremum in thoracic 10,thoracic 11 and lumbar 1 vertebra was compared between the models.ResultsPart 1 Clinical study:Logistic multivariate regression analysis found that bone mineral density,bone cement volume,rate of vertebral body height loss,follow-up height loss,paraptebral muscle fat infiltration,surgical method,bone cement distribution,whether the strengthened vertebra had a bone bridge,and whether intervertebral disc leakage occurred were all related factors in the occurrence of non-operative vertebral refracture after PVA(P<0.05).Among them,the lower the bone density,the much the degree of vertebral body height loss,and the higher the level of paraspinal muscle fat infiltration.In the patients who underwent PKP,the bone cement distributed in clumps,the enhanced vertebral body without bone bridge formation,and the incidence of non-operative vertebral body refracture after intervertebral disc cement leakage was higher.Enhanced anterior vertebral bridge formation and anti-OP are protective factors for recurrent fractures of adjacent vertebrae.Part 2 Clinical study:Logistic multivariate regression analysis showed that preoperative Cobb Angle,location of fracture area,endplate injury,PLC injury.lumbar fascia injury,operation type,and recollapse of enhanced vertebra were related factors to the formation of anterior bone bridge after PVA enhancement(P<0.05).See table below.Vertebrae forming the anterior bone bridge are usually associated with recollapse of vertebral height to varying degrees.Part 3 Finite element study:(1)The validity verification of the model shows that the complete model is highly realistic and can truly reflect the actual stress state;(2)Under mild or moderate compression conditions,Von Mises stress extremes of T10 vertebral cortex bone and cancellous bone were higher in the group with bone bridge than in the group without bone bridge under all exercise conditions.In the case of severe compression,the stress of cortical bone and cancellous bone of T10 vertebral body was not significantly different between the two groups.(3)Under mild compression conditions,Von Mises stress extremum of the cancellous bone of the T11 vertebral body was significantly lower in the group with bone bridge under all motion conditions than in the group without bone bridge,but there was no significant difference in moderate and severe fracture models.(4)There was no significant change in Von Mises stress extremum on the upper and lower endplates of each vertebral body in the group with bone bridge compared with the group without bone bridge.Conclusion1.Clinical study suggest that bone mineral density,bone cement volume,rate of vertebral body height loss,follow-up height loss,paravertebral muscle fat infiltration,surgical method,bone cement distribution,and disc leakage are risk factors for non-surgical vertebral refr acture after percutaneous vertebral augmentation,among which reinforcement of anterior vertebral bridge and anti-osteoporosis treatment are protective factors for postoperative adjacent vertebral refracture.2.Clinical study suggest that preoperative Cobb Angle,location of fracture area,endplate injury,posterior ligament complex injury,lumbar fascia injury,operation type,and recollapse of cemented vertebrae is related factors for the formation of anterior bone bridge after percutaneous vertebral body enhancement.According to X-ray and CT observation,bone bridge can be divided into top type,bottom type and mixed type,in which the top type is the majority.3.Finite element study suggest that when the anterior bone bridge is formed between the injured vertebra and the adjacent vertebra after single segment percutaneous vertebra reinforcement,the stress of the distal vertebra without bone bridge is significantly increased,while the stress of the adjacent vertebra is significantly reduced under mild or moderate vertebral compression,and the formation of bone bridge in the front of the injured vertebra may prevent the recurrence of the adjacent vertebra. |
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