Characteristics of the positional and morphological parameters of sagittal spine alignment in a cohort of 623 healthy individuals aged >50 years in China.

Study Design: A retrospective radiologic study.

Purpose: To investigate the spinopelvic positional and morphological parameters of the sagittal spinal alignment in a healthy population from the community.

Overview Of Literature: The existing parameters for spinal alignment based on the Cobb angle are the primary reference values for evaluating spinal alignment and pelvic morphology. However, they do not fully capture the comprehensive characteristics of sagittal spine alignment. More attention should be given to identifying the specific characteristics of sagittal spinal alignment by focusing on the positions of the kyphotic and lordotic apices.

Methods: Among 1,250 volunteers, 623 consecutive normal community volunteers aged >50 years were recruited and underwent standing postural X-ray. A customized computer application analyzed the sagittal morphological and positional parameters, examining their normal distributions and correlations.

Results: The correlation between the adjacent morphological and positional parameters was strong between the distal cervical and proximal lumbar spine. In the vertical direction, a significant association was found between the location of the thoracic kyphosis (TK) to lumbar lordosis (LL) transition point (TL point) and both the upper apex of TK (T-apex) (r=0.52) and lower apex of LL (L-apex) (r=0.64). In the horizontal direction, a moderate correlation was found between the thoracic apex offset to the femoral axis (TF) and the lumbar apex offset to the femoral axis (LF) (R2=0.314), whereas LF demonstrated a strong correlation with adjacent overhang (R2=0.685). Close correlations were observed among the morphological and positional parameters. The sacral slope exhibited significant correlations with two parameters related to the lumbar region: L-apex (r=-0.60) and LF (r=0.51).

Conclusions: This study found strong correlations between spinopelvic morphology and position, which is crucial for understanding sagittal alignment. Adjacent positional parameters showed significant compliance within the sagittal spine plane from the distal cervical to proximal lumbar regions, suggesting the necessity for additional research on its clinical relevance in spinal disease surgery.