Dislocation without fracture is seen in:

C i.e. Cervical spine The craniocervical junction refers to the structures that extend from the skull base to C2, and is comprised of occipital condyles, Cl and C2. It has high vulnerability to injury because of large lever arm induced rostrally by cranium and the relative freedom of movement of craniocervical junction which relies dispropoionately on ligamentous structures rather than on intrinsic bony stability. The upper five cervical spine rely primarily on intact ligamentous system for stabilityQ. This unique anatomical feature allows for substantial poion of neck movements. The alar ligaments (key structure), tectorial membrane (is rostral extension of posterior longitudinal ligament) serve as impoant stabilizer of craniocervical junction, as do, to a lesser extent the joint capsules of respective aiculations, anterior and posterior longitudinal ligaments. The primary stabilizing ligament of atlanto axial motion is the cruciate ligament complex which contains transverse atlantal ligament (TAL). So, Upper cervical spines has highest chances of dislocation with out fractureQ as their zygapophyseal (facet) joints slope in almost antero - posterior horizontal plane. Where as in thoracic & lumber region facet joints are oriented veically and inter locked.