Definition of Arthro-

Arthro-: A prefix meaning joint, as in arthropathy and arthroscopic. Before a vowel, it becomes arthr-, as in arthralgia and arthritis. From the Greek word arthron for joint. Ultimately from an Indo-European root meaning to join or to fit together.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=33983
Last Editorial Review: 6/14/2012