Divac originally hurt his back during a workout before training camp and was on the injured list from Nov. 2-23. He reinjured his back three weeks ago and was placed on the injured list Dec. 22.
The 7-foot-1 center has averaged 0.8 points, 1.1 rebounds and 0.5 assists in 4.6 minutes in eight games this season.
Divac, who was signed as a free agent by the Lakers in July, is a 15-year NBA veteran who began his career with the Lakers in 1989. He played for Sacramento last season.
Rookie guard Donta Smith, who has played only three minutes in two games, was activated to fill Delk's roster spot.
Delk is averaging 11.4 points in 22 games. He missed the first eight games with a knee injury.
Smith was placed on the injured list with a lower back strain on Nov. 30.
Sampson -- averaging 3.3 points, 5.2 rebounds and 12.9 minutes in 11 games -- was placed on the injured list on Dec. 29 because of a sprain ankle.
Smith, sidelined by tendinitis in his knee, is averaging 9.1 points, 1.5 rebounds, 2.0 assists and 19.8 minutes in 22 games.