It's often used in medical terms to describe procedures where an organ or tissue is surgically fixed in a new position. For example:
* Gastropexy: Fixation of the stomach
* Nephropexy: Fixation of a kidney
* Colpopexy: Fixation of the vagina
* Hysteropexy: Fixation of the uterus
The "pexy" part of these words indicates that the procedure involves surgically attaching or fixing something in place.