Nets coach Lawrence Frank defended the team's decision not to publicize the rib injury, saying it didn't force Kidd to miss any games and was only discovered when Kidd's back was being examined.
"The implication was that it was being concealed, which would be a falsehood," Frank said. "We're not going to disclose every nick, bruise or bump that's not preventing a guy from playing."
Unlike the NFL, the NBA does not require its teams to report injuries to the league office.
Kidd had been the subject of trade speculation that had intensified in recent days as Thursday's 3 p.m. deadline drew near. Reports had him heading to any of several teams, with the Los Angeles Lakers considered the clear favorite.
The Nets also entertained offers for Vince Carter, who can opt out of his contract at the end of the season. In the end, none came close to getting the Nets to move either player, according to team president Rod Thorn.
"Without divulging names or cities, we had conversations with a whole bunch of people, particularly in the last three to four days, and I can't say we ever got close to doing anything," Thorn said.
Kidd attended practice on Thursday but did not make himself available to reporters.
Frank said Kidd couldn't pinpoint when or how he cracked the rib, but that it could have happened during the Nets' game at Orlando on Feb. 2. In that game, Kidd was held scoreless in 25 minutes.
The 13-year veteran played in the Nets' next five games but sat out against the Raptors on Feb. 13 and the Spurs the next night. He pulled out of the All-Star game on Feb. 14.
Frank said the rib injury was discovered "almost by mistake" by the team's medical staff during examinations to diagnose the source of Kidd's back pain. It was determined that Kidd could play Wednesday night against New Orleans if he wore padding around his ribs.
The Nets, who already are without starters Nenad Krstic (knee) and Richard Jefferson (ankle) because of injuries, lost to the Hornets 111-107 to fall to 25-30, two games behind Miami for the Eastern Conference's eighth and final playoff spot.
In that game, his first since Feb. 10, Kidd shot 2-for-14 from the field and scored six points, though he had 14 assists and nine rebounds. After the game, Kidd said his back felt fine, but Frank said Thursday that Kidd was hurting and labeled him questionable for Friday night's game against Sacramento.
Carter scored a season-high 46 points against the Hornets, but only one other Nets starter scored in double figures. New Jersey failed to make up a game on the Heat, who also lost Wednesday and may have lost guard Dwyane Wade indefinitely with a dislocated shoulder.
"It's a great opportunity, but we still have to win games," Carter said Thursday. "We have to do it together as a unit. Right now it's all about finding a way and getting it done. There's no trickery; we have 27, 28 games to get it done. If not, it's going to be a long summer."