| Objective: To assess the biomechanical stability and range of motion (ROM)degeneration of upper adjacent vertebrae by biomechanics testing of the spinalexternal fixation for the adjacent double segments lumbar burst fractures.Methods: There were14vertebrae samples (T14～S1) from6fresh adult pigs. Eachof them had undergone a biomechanical test in the following order in order tominimize the inter-group interference.①Normal group, normal samples.②Fracturgroup, samples with fractures (L3, L4with burst fractures).③External fixation group,fracture samples with the spinal external fixation (L2, L5with the percutaneouspedicle screw).④Internal fixation group, fracture samples with the universal spinesystem. The biomechanical stability and upper vertebrae ROM of four groups aretested.Results:1. ROM in fracture group was significantly larger than that of normalgroup (p <0.05).2. ROM in the fixed groups was significantly less than that ofnormal and fracture groups (p <0.01). There’s no statistically significance changes ofSPI in both fixed group（sp>0.05）.3. Comparisons of upper vertebrae ROM betweenexternal fixation group and normal group in the following. There was no statisticallysignificance between flexion and extensionin（p>0.05）, but significantly differencebetween lateral bending and rotation (p <0.01). Comparisons of upper vertebraeROM between internal fixation group and normal group in the following. There wasstatistically significance among flexion, extension, lateral bending and rotation (p <0.01).Conclusion: Compared with traditional internal fixation, the biomechanical stabilityof the spinal external fixation in treating adjacent double segments of burst fracturewas equal. The reconstructive stability was satisfactory. Both two fixed methods increased ROM of adjacent upper vertebrae in lateral bending and rotation. But thespinal external fixation don’t lead to upper vertebrae ROM degeneration in flexionand extension, which was a better way in minimally invasive spinal surgery. |
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