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. 2025 Jul 8:21925682251353725.
doi: 10.1177/21925682251353725. Online ahead of print.

Normative Relationships Between Spinopelvic Alignment and Femoroacetabular Orientation: A Cross-Sectional Study

Taryn Ludwig  1 , Jonathan Bourget-Murray  1 , Sarup Sridharan  1 , Ariana Frederick  2 , Victoria Smith  2 , Kelly Johnston  1 , Nathan Evaniew  1   2 , Brent Edwards  3 , Michael Asmussen  4 , Fred Nicholls  1   2
Affiliations

Normative Relationships Between Spinopelvic Alignment and Femoroacetabular Orientation: A Cross-Sectional Study

Taryn Ludwig et al. Global Spine J. .

Abstract

Study DesignCross-sectional study.ObjectivesNormative data describing the relationship between spinopelvic and femoroacetabular alignment is not thoroughly described in the literature; we aimed to explore potential associations in healthy young adults.MethodsVolunteers with no hip or spine pathology were recruited for this study (N = 395.) Full body EOS scans were used to obtain 3D reconstructions of participants' acetabula and femurs. Associations between femoroacetabular parameters (acetabular anteversion (AA), acetabular inclination (AI), femoral version (FV)) and spinopelvic parameters (pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL)) were tested using multiple linear regression analyses.ResultsWe included 395 healthy volunteers (mean age 28.90 ± 5.1; 57% female; mean BMI 24.8 ± 4.2). Linear regression analysis demonstrated that AA is associated with PI, PT, age, sex and weight (R2 = 0.381). AI is largely conserved across participants, but associated with FV, PT, age, height and weight (R2 = 0.0949).ConclusionWe identified that normative relationships exist between acetabular orientation and spinopelvic parameters; however there remains residual variability in AA that is not comprehensively predicted by spinopelvic parameters alone. This knowledge provides the foundation for understanding changing alignment with normal aging and compensatory mechanisms. This will ultimately help guide restoration of pre-degenerative acetabular orientation in THA and spinopelvic alignment in spinal fusion in order to optimize patient care and reduce the need for revision surgery.

Keywords: femoroacetabular alignment; normative alignment; pelvic incidence; spinopelvic alignment.

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Conflict of interest statement

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
Representative images demonstrating each Roussouly morphotype from the current study cohort. Red: pelvic incidence (PI). Green: sacral slope (SS). Yellow: lumbar lordosis (LL).
Figure 2.
Figure 2.
Sample sagittal (A) and coronal (B) Keops semi-automated image segmentation showing user-defined anatomic landmarks.
Figure 3.
Figure 3.
(A) Sample image of pelvic, acetabular, and femur parameters from EOS. (B) Schematic of spinopelvic and femoroacetabular parameters obtained from EOS 3D reconstruction (AA = anatomic anteversion, RA = radiographic anteversion, OA = operative anteversion). Adapted from Refs. ,.
Figure 4.
Figure 4.
Confirmation of normally distributed data for key parameters. (A) Acetabular anteversion (AA), (B) Acetabular inclination (AI), (C) Pelvic incidence (PI), (D) Pelvic tilt (PT), (E) Lumbar lordosis (LL), (F) Femoral version (FV).
Figure 5.
Figure 5.
Right vs left AI (A) and AA (B) difference in degrees.
Figure 6.
Figure 6.
Unadjusted comparisons showing significant associations of acetabular anteversion (AA) in final regression model. (A) AA vs PI, (B) AA vs PT, (C) AA vs age, (D) AA vs weight. Line of best fit and linear equation shown inset.
Figure 7.
Figure 7.
Unadjusted comparisons showing significant associations of acetabular inclination (AI) based on final regression model. (A) AI vs FV, (B) AI vs PT, (C) AI vs age, (D) AI vs height, (E) AI vs weight. Line of best fit and linear equation shown inset.
See this image and copyright information in PMC

References

    1. Roussouly P, Gollogly S, Berthonnaud E, Dimnet J. Classification of the normal variation in the sagittal alignment of the human lumbar spine and pelvis in the standing position. Spine (Phila Pa 1976). 2005;30(3):346-353. doi: 10.1097/01.brs.0000152379.54463.65 - DOI - PubMed
    1. Schwab F, Farcy JP, Glassman S, Harrast J, Horton W, Bridwell K. A clinical impact classification of scoliosis in the adult. Spine (Phila Pa 1976). 2006;31(18):2109-2114. - PubMed
    1. Haddas R, Sambhariya V, Kosztowski T, Block A, Lieberman I. Cone of economy classification: evolution, concept of stability, severity level, and correlation to patient-reported outcome scores. Eur Spine J. 2021;30(8):2271-2282. doi: 10.1007/s00586-020-06678-z - DOI - PubMed
    1. Grammatopoulos G, Speirs AD, Ng KCG, et al. Acetabular and spino-pelvic morphologies are different in subjects with symptomatic cam femoro-acetabular impingement. J Orthop Res. 2018;36(7):1840-1848. doi: 10.1002/jor.23856 - DOI - PubMed
    1. Khoury AN, Hatem M, Bowler J, Martin HD. Hip–spine syndrome: rationale for ischiofemoral impingement, femoroacetabular impingement and abnormal femoral torsion leading to low back pain. J Hip Preserv Surg. 2021;7(3):390-400. doi: 10.1093/jhps/hnaa054 - DOI - PMC - PubMed

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