Tuesday’s blockbuster NBA trade between the Cleveland Cavaliers and the Boston Celtics has technically not been finalized, and according to multiple reports the proposed deal is hitting a snag due to concerns about Isaiah Thomas’ hip injury. 

Thomas missed several games as the Cavs and Celtics faced off during last season’s Eastern Conference Finals after re-aggravating a right hip injury he suffered during Game 6 of the Celtics’ second-round series against the Washington Wizards. While some reports referred to that injury as a hip strain, both the exact nature of the injury and when Thomas originally hurt his hip are unclear.

NBA bylaws require both teams participating in a trade to disclose in writing all information held by the respective team’s players relevant to the player’s health and ability to play basketball. The players are also required to take physical examinations, which Thomas completed Friday.

Perhaps more telling were statements Celtics general manager Danny Ainge made earlier this week about Thomas’ health impacting the trade.

“There’s gonna be probably a little bit of a delay for Isaiah as he starts the season this year, but I think that Isaiah should be fine and healthy as the season goes along,” Ainge said. He also confirmed that Thomas’ health concerns played “some” role in trading the star point guard after he put up one of the more efficient high-volume scoring seasons in league history.

“Uncertainty over the fitness of his injured hip has Cavaliers officials evaluating the results and considering possible ramifications to the blockbuster trade that sent Kyrie Irving to the Boston Celtics earlier this week,” ESPN’s Adrian Wojnarowski reported.

In a new report by Wojnarowski, league sources say Cavs officials are planning to seek an additional trade asset that could threaten to veto the trade. If the deal isn't finalized, both organizations would have to weigh the consequences of allowing the players to return to Boston and Cleveland respectively.

Kyrie Irving is reportedly scheduled to take his physical with the Celtics Saturday, and the All-Star point guard comes with his own injury concerns. Irving’s college career at Duke was limited to 11 games due to a foot injury. In three of Irving’s six seasons in the NBA, he has played less than 60 of a possible 82 games due to injuries. 

In June of 2015, Irving left Game 1 of an NBA Finals matchup against the Golden State Warriors with a fractured kneecap. The injury required season-ending surgery and led to him missing a portion of the following season while recovering.