The distal arch is almost absent, the apex is very low, close to L5 and LL is quite constructed by only the proximal arch. Lumbar lordosis is short and, therefore, the kyphosis is long, with an extension on the thoraco-lumbar area. In summary, it is a non-harmonious back with thoraco- lumbar kyphosis and short hyperlordosis. Low pelvic incidence.
The distal arch is low; it is longer but flat, close to a straight line. It is a harmonious flat back. Mean sacral slope (35° - 45°), low pelvic incidence.
Lumbar lordosis is well balanced between its two arches. It is a harmonious regular back. High sacral slope (> 45°), high pelvic incidence.
The distal arch is highly increased in angle and number of vertebrae; length and curvature of lumbar lordosis increase. It is a harmonious hypercurved back. High pelvic incidence.
Roussouly P, Pinheiro-Franco JL. Biomechanical analysis of the spino-pelvic organization and adaptation in pathology. Eur Spine J. 2011 Aug 2;20(S5):609-18.
Sagittal spino-pelvic alignment in chronic low back pain
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Je´roˆme Paquet • Eric Berthonnaud •
Fabienne Siani • Pierre Roussouly. Eur Spine J (2011) 20 (Suppl 5):S634–S640
Sagittal plane deformity: an overview of interpretation
and management Pierre Roussouly • Colin Nnadi
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