Lumbar shape characterization of the neural arch and vertebral body in spondylolysis: A comparative skeletal study

The lumbar vertebral shape is an important causative factor in spondylolysis (SP). However, a complete characterization of this shape, that would shed light on its pathophysiology enhance its earlier diagnosis, is still missing. The aim of this study was to evaluate the shape distinctiveness of the lumbar (L1-L5) vertebral body (VB) and neural arch (isthmus, lamina, vertebral canal, spinous, and transverse processes) in SP. Using a three-dimensional (3D) digitizer, the VB length, width, height, and sagittal wedging as well as the lengths of the isthmus, lamina spinous, and transverse processes of all lumbar vertebrae (L1-L5) were measured from 115 male skeletons with bilateral SP at L5 and compared with 120 normal ones. Compared with the normal group, the following results were indicated in SP [analysis of variance (ANOVA), P < 0.05]: the VB's are significantly longer at the superior surfaces of L1-L4 and inferior surfaces of L1-L3 (total mean difference = 7.61 mm and 3.94 mm, respectively), and wider at the superior surfaces of L1-L4 and inferior surfaces of L1-L5 (total mean difference = 10.06 mm and 12.90 mm, respectively); The L5 VB is significantly shorter posteriorly (mean difference = 3.05 mm) and more lordotic (+1° of dorsal wedging); L5 is manifested with longer lamina (mean difference = 1.85-2.18 mm), longer isthmus (mean difference = 3.24-4.69 mm), and longer and wider vertebral canal (mean differences = 3.64 mm and 1.13 mm, respectively); The L2-L5 spinous processes are significantly longer (total mean difference = 7.45 mm). Clinically, detecting the aforementioned unique lumbar vertebral morphometric features in individuals suffering from chronic low back pain may facilitate the early diagnosis of SP.