Comparative Analysis Of Two Imaging Modalities For Measurement Of Lumbar Sagittal Parameter

Objectives: To measure and analyze lumbar sagittal parameter lamina-pedicle angle(LPA)on X-ray and computed tomography(CT)three-dimensional reconstruction,thus to explore the feasibility of LPA in posterior lumbar pedicle screw fixation.Methods: 100 patients including 50 males and 50 females who underwent posterior lumbar pedicle screw fixation operation were randomly selected.These patients suffered from back pain or leg pain preoperatively.Both X-ray and axial CT images were obtained preoperatively.The lumbar LPA of each patient was measured on lateral X-ray and sagittal plane of CT reconstructions from L1 to L5 segment in PACS system,and both left and right side data were measured on CT.Results: Both X-ray and CT data showed the LPA decreased gradually from L1 to L5 segment.Specifically,it decreased from71.14°±3.73° to 58.70 °±4.93 ° in X-ray,from 72.76 °±2.60° to 58.81 °±3.13° in CT.There was no significant difference in different genders(P > 0.05).In CT,LPA was almost the same between left and right side(P> 0.05).Except for L1 and L4,there was no difference between X-ray and CT for LPA in the rest lumbar segments(P > 0.05).Conclusion: There are few variation and degenerative changes in lumbar lamina,and it is easy to be dissected and exposed during operation.Thus it can be used as an anatomical reference for free-hand technique.LPA shows a gradual decrease from L1 to L5 segment,which can serve as a reference for surgeons to some extent.