Which suffix means "surgical fixation"?

The suffix that means "surgical fixation" is indeed -pexy. This suffix is commonly used in medical terminology to describe procedures that involve securing or fixing an organ in a specific position. For example, in the term "orchidopexy," this indicates the surgical fixation of the testes. Understanding this suffix can help in comprehending numerous medical terms related to surgical procedures aimed at stabilization.

The other suffixes do not convey the same meaning: -trophy refers to nourishment or growth; -in is a generic suffix that can denote substances, particularly in biochemistry; and -plasia indicates formation or development, often used in terms like "hyperplasia," which refers to an increase in the number of cells. Thus, -pexy is clearly the most appropriate choice for the meaning of "surgical fixation."