Geometry of thoracolumbar vertebral endplates of the human spine

Novel and better vertebral body replacement constructs are always desired by surgeons. Endplate geometry is crucial for the design of those implants, but current literature on that topic is very scarce. The authors present a morphometric study of thoracolumbar vertebral endplates, the goal of which was to analyze the geometry of endplates from T10 inferior to L3 superior by employing data from CT scans, as well as to verify the reliability of data derived from the CT measurement. Reformatted CT scans of 83 individuals were analyzed and sagittal concave angle, location of concave region, sagittal diameter of endplate, coronal concave angle, as well as transverse diameter of endplate were measured in midsagittal plane and specified coronal plane. The data of CT and cadaveric measurements of ten cadaveric specimens were also compared. Age and gender did not influence sagittal concave angle, location of concave region, and coronal concave angle significantly (P > 0.05). No significant difference has been revealed among each endplate for sagittal concave angle (range 162.5°-163.9°) and location of concave region (range 42.5-44.2%), either. Ranging between 170.9° and 175.7°, coronal concave angle was constantly larger in superior endplate than in inferior one. The sagittal and transverse endplate diameters of females were significantly smaller than those of males (P < 0.05), being about 88% of the latter one. The mean difference between CT and cadaveric measurements was small (Cronbach alpha > 0.8). Those morphologic parameters, especially the concavity of endplates, should be taken into consideration when designing novel vertebral body replacement constructs. CT measurement data could be used to calculate most suitable geometric parameters of those implants.