Johnson underwent the procedure two weeks ago and is focused on getting ready for the start of training camp in late July.
Injuries to both hamstrings limited Johnson to seven games during the 2011 regular season. Johnson posted career lows in receptions (33), receiving yards (492) and equaled a career low with two touchdowns. Johnson added 13 receptions for 201 yards and a touchdown in two playoff games.
It's worth noting that Johnson missed the final seven games of the 2007 season with a left knee injury that required a scope that knocked him out of the 2008 OTAs. Johnson would go on to lead the NFL in receptions (115) and receiving yards (1,575) that season, but was 27 years old back then. Johnson will turn 31 in July.
In other Texans injury news, quarterback Matt Schaub was at the Texans' team facility Monday watching practice, McClain reports. Schaub had his season cut short after 10 games because of a Lisfranc injury to his right foot.