Anatomical sacral slope, a new pelvic parameter, is associated with lumbar lordosis and pelvic incidence in healthy Japanese women: A retrospective cross-sectional study

• Published in: Journal of orthopaedic surgery (Hong Kong) Vol. 28; no. 1; p. 2309499019888809
• Main Authors: Suzuki, Hayato, Imai, Norio, Nozaki, Asami, Hirano, Yuki, Endo, Naoto
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.01.2020; Sage Publications Ltd; SAGE Publishing
• Subjects: Aged; Aged, 80 and over; Cross-Sectional Studies; Female; Humans; Imaging, Three-Dimensional - methods; Incidence; Japan - epidemiology; Lordosis - diagnostic imaging; Lordosis - epidemiology; Lumbar Vertebrae - diagnostic imaging; Middle Aged; Pelvis - diagnostic imaging; Posture; Radiography; Reference Values; Retrospective Studies; Sacrum - diagnostic imaging; Japan; pelvis; spine; lordosis; anatomy; sacrum
• ISSN: 2309-4990; 1022-5536; 2309-4990
• DOI: 10.1177/2309499019888809

Purpose: Anatomical sacral slope (a-SS), a pelvic anatomical parameter that does not require the center of the femoral head, strongly correlates with pelvic incidence (PI) during three-dimensional measurements in normal subjects. Sagittal alignment of spinal and pelvic parameters is typically evaluated using two-dimensional radiographs; however, the relationship between a-SS and PI has not been evaluated using radiographs. This study aimed to evaluate the correlation between a-SS and other spinal and pelvic parameters using radiographs. Methods: We evaluated 144 healthy women. Using sagittal radiographs, we measured lumbar lordosis (LL), thoracic kyphosis, PI, SS, pelvic tilt, and a-SS, which were defined as the angle between the superior end plate of S1 and a line perpendicular to the anterior pelvic plane. Pearson coefficients were used to determine correlations, and intraobserver and interobserver intraclass correlation coefficients (ICCs) were used for validation. Results: There was a strong correlation between PI and a-SS (r = 0.756). Moreover, correlations between a-SS and LL and between PI and LL were similar (r = 0.661 and r = 0.554, respectively). The intraobserver ICCs were 0.884 for a-SS and 0.840 for PI. The interobserver ICCs were 0.856 for a-SS and 0.653 for PI. Conclusion: a-SS was strongly correlated with PI. The correlation between a-SS and LL was equivalent to the correlation between PI and LL. Moreover, the ICC for a-SS was larger than that of PI. This study suggests that a-SS is a useful new pelvic anatomical parameter that can be used instead of PI.