Structural Mechanics Report

The Keystone Of Movement.

The Pelvis connects your spine to your legs. The Sacroiliac (SI) Joint is the bridge. Pain occurs when this bridge becomes too loose (instability) or gets stuck (locking).

The 3 Pillars of SI Health

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    Form Closure: How well the bones (Sacrum & Ilium) fit together like a puzzle.

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    Force Closure: Muscles (Glutes/Lats/Abs) squeezing the joint tight to handle load.

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    Load Transfer: The SI Joint transfers 100% of upper body weight to the legs.

The Pelvic Ring

It is a rigid ring containing three joints: Two SI joints at the back and the Symphysis Pubis at the front.

The Sacrum (Wedge)

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Spine Base

SI Joint (The Gap)

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The Shock Absorber

The Ilium (Wings)

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Hip Bones

The Physics of Stability

The SI joint barely moves (only 2-4 degrees). Problems arise when it moves too much (instability) or when forces aren't distributed evenly (shear).

Shear Force by Activity

Joint Stress

Single-leg activities (Walking/Stairs) create massive vertical shear forces that the glutes must counteract.

Why the SIJ Fails

Root Cause

Unlike the spine, SIJ pain is often due to 'Instability' (too loose) rather than 'Stiffness' (too tight).

Stability Protocols

Select a focus: Compress (Strength) or Align (Reset).

Daily Pelvic Stability

If you have SI pain, focus on symmetry and glute activation. Avoid asymmetrical stretching until stable.

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