Yes, you can see the impact of poor sitting position downstream at the knee.
Everything starts with the spine.
If the spine is in a poor position things are compromised at the big engines of the hip and shoulder.
Your knee/leg issue could originate at the hip.
There can be different causes of ITB. Sounds like you reached your body’s tolerance for the compromised position. Have you done anything to address your knee?
Here are some to start with
Pro Episode # 35 – MWod Pro-User Request Friday: The IT Band Primer
Episode 361: Pathomechanics and IT Band Hell Part 1
Episode 361: Pathomechanics and IT Band Hell Part 2
Episode 361: Pathomechanics and IT Band Hell Part 3
Episode 352: Dealing With Old Junky Tissue

Episode 343: Stop Walking Like the Duck You Aren’t

Sitting position
Episode 276: MobilityWod Google Talk: Desk Bound

Episode 88: Desk Athlete Hip Rescue
Episode 15: You Must Defeat The Evil Chair Part 1
Episode 15: You Must Defeat The Evil Chair Part 2