Spinal profile

Scientific basis

In 2005, Pierre Roussouly described four types of spinal profiles in people without pain, based on the sacral slope and the shape of the lumbar lordosis: from type 1, with a slightly inclined pelvis and a short lordosis, to type 4, with a steeply inclined pelvis and a pronounced lordosis. The classification was later completed with a variant known as "anteverted type 3".

These profiles are largely determined by pelvic incidence, a fixed angle specific to each person. They are not abnormalities: they are normal variants, which are not exposed to the same stresses depending on the position.

Blue Portance / SBNFA™ reading

SBNFA™ builds on this variety to define a natural balance profile specific to each person. A principle follows from it: a seat should not impose the same geometry on everyone, but remain compatible with the organization of the person's pelvis and spine.

The idea that each profile responds differently to a standard seat, and calls for different adjustments, belongs to the SBNFA™ reading.

Contribution to the analysis of sitting

A seat can be analyzed according to the pelvic orientation it imposes and its compatibility with the person's profile, for example through knee height or seat tilt.

Not to be confused with

Pelvic incidence, a pelvic parameter that partly determines the profile; posture, the position adopted at a given moment; scoliosis, a deformity of the spine in the frontal plane.

Related terms

Cone of balance · Pelvic incidence · Posterior pelvic tilt

Sources and scope

• Roussouly et al. (2005): classification of the normal variation in the sagittal alignment of the human lumbar spine and pelvis (Spine)
• Laouissat et al. (2018): revision of the Roussouly classification (European Spine Journal)
• Barrey et al. (2013): compensatory mechanisms of spinal sagittal balance (European Spine Journal)