Spanish to English Other Manufacturing (luxury) boot making

Text describing the process of boot making.
Have done quite a bit of research and i suspect "quiebres" can be translated in English as "waist":

Waist (Shank)
The narrow part of a shoe sole or insole under the arch of the foot. (See also Shank)[Thornton/Swann, 1983][Webber, 1989]
The narrow middle part of the last, the shoe or the sole, corresponding with the instep and the arch of the foot. [Goubitz, 2001]
http://www.personal.utulsa.edu/~marc-carlson/shoe/RESEARCH/G...

However not sure how to translate the phrase "quiebres altos". Could it maybe mean high instep/high arch? narrow waist?

Thanks in advance for any help you can give.

MAQUINA DE MOLDEAR.- Sirve para dar forma a **botas con quiebres altos** y para ceñir la piel a la horma.