No flexion is involved, so using rigid ceramics is not a problem.

ECONOMIST: Superconductors are starting to become useful

More important, it was Dr. Kathy who introduced the boy to the concepts of spine as microcosm and of spinal hygiene and postural echo and incrementalism in flexion.

NEWYORKER: Backbone

After digging into the sand between the crossties, it jammed between two of the spokes, went blue from the heat and tension at the point of flexion, and brought the car to a stop.

NEWYORKER: Among Animals and Plants

It had also been the orbicularis muscles, more than any outstanding advance in vertebral flexion, that had permitted him to access the rear areas of his scrotum and substantial portions of the papery skin around his anus before he turned nine.

NEWYORKER: Backbone