Stewart (knee) underwent arthroscopic surgery on his left knee Tuesday, Adam Berry of MLB.com reports.

EDGE Analysis

Given that the Pirates had ruled him out for the season, Stewart decided to get a head-start on his recovery process and undergo surgery prior to the end of the season. The recovery time for this procedure is typically 6-to-8 weeks, so as long as everything goes as planned, the veteran backstop should be back in time for spring training.