The 21-year-old has impressed Pools manager Colin Cooper while training with the League Two club and is likely to spend at least half the season at Victoria Park.
Cooper told The Northern Echo: "We've agreed a loan with Middlesbrough. Christian is someone I've a lot of time for.
"If we do what I really want to do, then we need people who can defend and play football and he can certainly do that and he will be an asset for this club.
"At this moment I think it will be a loan deal until Christmas, then we will reassess it.
"I've no doubt he will play for Middlesbrough in his career, but at the moment (Middlesbrough manager) Tony (Mowbray) believes his development is ongoing.
"He's played in pre-season for them and I think he will be a good acquisition for us."