In adults, cervical instability most commonly results from: (A) A rotational injury, (B) A flexion extension injury, (C) Degenerative disc disease, (D) Increased ligamentous laxity
Answer is C. Cervical instability, defined as AP subluxation of more than 3.5 mm or sagittal angulation greater than 20deg on flexion-extension radiographs, most commonly results from disc degeneration, with its attendant changes in the facet joints and loss of ligamentous suppo. Ref: internet sources