The mechanism of thoracolumbar burst fracture may be related to the basivertebral foramen

Publication date: Available online 18 August 2017
Source:The Spine Journal
Author(s): Xuyang Zhang, Shengyun Li, Xing Zhao, Blaine A. Christiansen, Shunwu Fan, Fengdong Zhao, Jian Chen
Background ContextThe basivertebral foramen (BF), located in the middle posterior wall of the vertebral body, may induce local weakness and contribute to the formation of a retropulsed bone fragment (RBF) in thoracolumbar burst fracture (TLBF). We hypothesize that the mechanism of TLBF is related to the BF.PurposeTo clarify the relationship between retropulsed bone fragments and the basivertebral foramen in thoracolumbar burst fractures, and to explain the results using biomechanical experiments and micro-CT.Study DesignA comprehensive research involving clinical radiology, micro-CT, and biomechanical experiments on cadaveric spines.Patient SampleA total of 162 consecutive patients diagnosed with thoracolumbar burst fracture with RBFs, drawn from 256 patients who had reported accidents or injuries to their thoracolumbar spine.Outcome MeasuresDimensions and location of the RBFs in relation to the BF.MethodsCT reconstruction imaging was used to measure the dimensions and location of RBFs in 162 patients (length, height, width of RBF and vertebral body). Furthermore, micro-CT scans were obtained of ten cadaveric spines. Each vertebral body was divided into three layers (Superior, Middle, Inferior), and each layer was divided further into 9 regions (R1 – R9). Microarchitecture parameters were calculated from micro-CT scans, including Bone Volume Fraction (BV/TV), Connectivity (Conn.D), Trabecular number (Tb.N), Trabecular Thickness (Tb.Th) and Bone Mineral Density (BMD). Differences were analyzed between regions and layers. Burst fractures were simulated on cadaveric spines in order to explore the fracture line location and test the relationship between RBFs and BF. This study was partially supported by 2016 National Natural Science Foundation of China (No. 81672208) (¥520,000).ResultsRBF width was usually one-third of the width of the vertebral body, whereas RBF length and height were approximately half of the corresponding vertebral body dimensions. Measures of trabecular bone quality were generally lowest in those central and superior regions of the vertebral body which are adjacent to the BF and which are most affected by burst fracture. In simulated thoracolumbar burst fractures, the fracture line went across the vertex or upper surface of the BF.ConclusionsThe most vulnerable regions in the vertebral body lie within or just superior to the basivertebral foramen. The central MR2 region in particular is at risk of fracture and RBF formation.



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