Helical CT Three-dimensional Reconstruction Or Measurement Of The Lumbar Facet Joint And Its Clinic Meaning

Background Recently,accompanied by deepening understanding of facet joint may be a pain source in chronic back pain, facet joint arthroplasty is on the agenda. However,We can not easily carry out an overall observation of their shape on image or in surgery because of their complicated geometric anatomic structures and concealed position. The shape of facet joint has been reported before, they were classified into 4 types (the parallel, the embrace, the reverse embrace, the double embrace) by domestic scholars and 2 types ( the straight, the curved) by international scholars. But I found that the shapes or curvature of the two surfaces of one facet joint are dissimilarity frequently and prevenient research are limited on the transverse plane. Three- dimensional morphology of the lumbar facet joint has not been reported yet.Objective To study the three-dimensional anatomic and quantitative morphology of the lumbar facet joint and its clinic meaning.Materials and MethodsSpecimensThis study included 60 people without spinal complaints (30females, 30males ; average age, 37.2 years ; age range, from 18 to 58 years) who were referred between May and October 2008 to our department for 64-row multi-detector CT scans of the lumbar spine. People with abnormalities,such as disc herniation , spinal stenosis , tumors, and infections,were excluded from the study.Methods1)CT Scan Protocols: All CT examinations were performed with a Siemens Volume Zoom 64-row multi-detector CT scanner (Germany).All spiral data sets were reconstructed with 1 mm slice thickness and 0.7 mm increment using a hard Kernel(B70S) and a bone window(width 2500 HU, level 500 HU).The image evaluation was done on digital workstations(Siemens, Germany).2)The transverse images:Transverse images were acquired parallel to the superior endplate of the corresponding vertebral body. Superior and inferior articular surfaces are studied respectively. According to the shapes,they are classified into 7 types(type I"l",type II"C",type III"J",type IV"S",type V"3", type VI">", type VII others).Facet width,joint angle and articular space are measured severally.3)the coronal images:coronal images were acquired parallel to the joint space on both the transverse plane and the sagittal plane. The joint surface shapes are classified into 5 types(type I ellipse,type II rectangle,type III pentagon,type IV hexagon,type V others).4)the sagittal images:sagittal images were acquired perpendicular to the joint space on the transverse plane. The heights are measured. 5)Statistical Methods:Statistical analysis for descriptive statisticswas performed using SPSS10.0. Data obtained were analyzed with frequency and descriptive statistics. Statistic and Mathematic data analysis were performed using the t test andχ~2 test respectively. A P value of <0.05 was considered to be significant. Results are presented as means±standard errors.ResultsOn the horizontal plane ,the shapes of L1-2 superior and inferior both"C"with equally curvature. The shapes of L2-3, L3-4, L4-5 superior and inferior facet joint are both"C"with different curvature. At the level of L5-S1,the shape of superior facet joint is"C"and the shape of inferior facet joint is"l"in male, while the shapes of superior and inferior facet joint are both"l"in female. The dimensions of facet widths and joint angle were gradually bigger from L1-2 to L5-S1. The L4-5 and L5-S1 joints tend to be more coronally positioned , whereas the L1-2,L2-3,L3-4 joints are oriented more parallel to the sagittal plane. The joint spaces were gradually bigger from L1-2 to L4-5, and the values of L5-S1 were in the middle of that of L3-4 and L4-5. On the coronal plane , the shapes of L1-2, L2-3 facet joint are both ellipse. At the level of L3-4, the shape is ellipse in male and rectangle in female. At the level of L4/5, the shape is ellipse in male and rectangle/ ellipse in female. At the level of L5-S1, the shape is roundness in both male and female or the shape is square in male and rectangle in female. The dimensions of facet areas were gradually bigger from L1-2 to L5-S1.On the sagittal plane, the shape is"l".ConclusionsThe standard shapes of lumbar facet joints are dissimilarity frequently at different level, plane and gender. In clinical work, we must analyze them respectively. At the level of L5-S1, the morphology of the facet joint have advantage to keep lumbar stability for its straight joint surface, the biggest angle, the biggest area and narrower space. We have explored their standard morphology , and that provides important information for clinic to diagnose facet joint source low back pain. The foundation of three-dimensional anatomical model provides theory reference for artificial facet joint replacement.