On Monday, Henry was diagnosed with a bone bruise and an "abnormality of the lateral meniscus" in his right knee.
Henry left with a little over a minute left in the first quarter Sunday night, in a loss to the Philadelphia 76ers, after stepping awkwardly.
Henry was examined by Dr. Steve Lombardo of the Kerlan-Jobe Orthopaedic Clinic.
He'll be reevaluated in seven to 10 days.
Through 31 games, Henry was averaging 10.1 points a game while shooting 42.5% from the field.
The Lakers are also without Steve Blake (elbow), Steve Nash (back) and Kobe Bryant (knee) for at least the month of January. Henry, like Bryant, was playing out of position at point guard when injured.
Jordan Farmar recently returned from a torn hamstring after a three-week layoff, but sat practice Monday as precaution.
Recent signee Kendall Marshall will probably be asked to pick up Henry's minutes at backup point guard while Jodie Meeks, Nick Young and Wesley Johnson will probably need to play added minutes at shooting guard.
The Lakers have lost five straight to fall to 13th in the Western Conference at 13-18.