The Ravens have signed veteran CB Chris Johnson to shore up a position thinned by injuries. (US Presswire)

In a move that could signal concern with one of Baltimore's starting cornerbacks, the Ravens signed veteran CB Chris Johnson on Tuesday. 

To make room for Johnson, Baltimore placed RB Bobby Rainey on injured reserve with a previously undisclosed knee injury. 

With the Ravens signing a cornerback, it could signify they are worried about CB Jimmy Smith's health. Smith is dealing with a groin injury that kept him out of Baltimore's 55-20 win over Oakland on Sunday. Smith, who became a starter after CB Lardarius Webb tore his ACL against Dallas in Week 6, was Baltimore's first-round draft choice in 2011. On Monday, coach John Harbaugh said the Ravens' staff would take a "hard look" at the injury that's bothering Smith. 

With Smith out against the Raiders, CBs Corey Graham and Chykie Brown saw extensive action. In eight previous games played, Smith has 28 tackles and three pass deflections. Johnson (6-foot-1, 200 pounds) is of similar build as Smith (6-2, 205). 

Johnson is an eight-year veteran who was drafted by the Packers out of Louisville in 2003. He has played 73 games with 30 starts. He was most recently with the Raiders from 2007-2011 and went on injured reserve with hamstring and groin issues in December. Johnson did not begin the 2012 season with any NFL team. 

Johnson has 157 tackles and eight interceptions, one of which was returned for a touchdown, in his career. 

In addition, the Ravens re-signed QB Dennis Dixon to their practice squad, who was previously released almost a week ago. To make room for Dixon's return, Baltimore cut S Omar Brown.

Follow Ravens reporter Jason Butt on Twitter: @CBSRavens and @JasonButtCBS.