CT measurement of sagittal endplate morphology of the adult lower lumbar spine

Objective To measure the sagittal endplate morphology parameters of the adult lower lumbar spine (L3-S1) and to explore its significance in the design and modification of the artificial intervertebral disc and interbody fusion cage. Methods Three-dimensional CT reconstructions of the lumbar were obtained in 80 healthy adult volunteers. Sagittal concavity angle (SCA), endplate concavity apex (ECA) and endplate concavity depth (ECD) of the L3 inferior endplate to S1 superior endplate in the midsagittal plane were measured. According to the age (>40 years or ≤40 years) and gender, we divided all the CT images into four groups. The sagittal shapes of the endplate were divided into flat, oblong and ex-centric at the same time. The sagittal shapes of the endplate, the endplate SCA and ECD, the ECA of oblong and ex-centric endplates among different groups, the inferior and superior endplate of the same vertebral and the adjacent endplate ECD of the same segment were measured and compared. Results A sexor age-related difference could not be found among the sagittal shapes of the endplate. The locations of oblong ECA were only found different between the ones of ex-centric endplates in the superior endplate of L3, the superior and inferior endplate of L5. The difference between ECD of superior endplate of L5 in men less than forty years old and women less than forty years old was significant. The inferior endplate ECD was always larger than the superior endplate ECD in the same vertebral (L4, L5). In each segment (L3,4, L4,5, L5S1), ECD was smaller in the inferior endplate of the superior vertebra than in the superior endplate of the inferior vertebra (P<0.05). Conclusion Most of the endplates of the lower lumbar spine are concave besides the superior endplate of S1. And the location of concave endplate ECA is always found in the posterior half of the lumbar endplates. Age and gender have certain effect on the sagittal ECD, but not on sagittal shapes or ECA. Key words: Adult; Lumbar vertebrae; Tomography, X-ray computed