PELVIC STABILITY GRADIENT TAXONOMY

The Pelvic Stability Gradient (PSG) Taxonomy establishes a Newtonian framework for understanding human pelvic stability as a force‑containment requirement rather than a mass‑based property. It defines pelvic stability as the inward clamp force needed to maintain pelvic alignment against the largest applied vector acting on the human trunk. As stated in the taxonomy, the PSG expresses the relationship between measured clamp force, applied vector magnitude, and containment capacity, providing a clear mechanical basis for evaluating structural risk. The taxonomy identifies real‑world applied force sources that routinely exceed body weight, including athletic torque, occupational load spikes, impacts, and asymmetric internal forces. It outlines how pelvic instability occurs when applied force exceeds clamp force, producing drift, collapse, misrouting, ligament overload, and rotational failure. High‑vector case studies—such as fast bowlers, rodeo riders, weight lifters, and crash victims—demonstrate the universality of these mechanics. The PSG model incorporates baseline and dynamic clamp force, applied vector magnitude, and containment ratio, enabling activity‑specific stability assessment. It further distinguishes Earth‑gravity stability from low‑gravity environments, where gravity’s stabilising bias disappears and clamp force must replace it entirely. The taxonomy identifies clamp force—abdominal, core, and chest—as the only controllable stabilising force available to humans. It defines structural‑risk bands, outlines reinsurer applications, and extends the model to children, animals, and infants born with near‑zero clamp‑force capacity. The PSG Taxonomy forms a foundational component of the Newtonian Force Origin Taxonomy Series and provides a complete structural‑risk interpretation of pelvic stability.