In a surprise move, the nonprofits buying St. Christopher’s Hospital for Children are not bringing on the head of its neonatal heart surgery program that’s key to maintaining the hospital’s status as a trauma center.

The employment contract of Achintya Moulick, the hospital’s chief medical officer, the executive director of its heart center, and chairman of cardiothoracic surgery, was on a list of contracts not being “assumed” by the buyers, according to a court document. In a bankruptcy sale, “assuming” a contract means the buyer will fulfill the terms of a contract entered into by the previous owner.

Moulick’s exclusion plunged the critical unit at the North Philadelphia hospital into uncertainty on Monday, when Tower Health and Drexel University received court approval to buy St. Christopher’s out of bankruptcy. The heart surgery program accounts for a significant portion of the hospital’s revenue.

Moulick was a strong advocate for the purchase of St. Christopher’s by a consortium led by Jefferson Health, which decided not to bid. He told U.S. Bankruptcy Judge Kevin Gross that the decision not to take his contract, the terms of which are not public, was retribution.

“I was on the side of St. Christopher’s Hospital,” said Moulick, who has been there since 2009.

The decision “is hasty and not well thought out, unless St. Christopher’s plans to bring in another institution to perform cardiac surgeries. Such a transaction will not benefit St. Christopher’s or its patients,” Moulick’s lawyer said in a court filing.

It’s not clear what plans Tower and Drexel have for the heart surgery program. “I can’t speak to that,” said Clint Matthews, chief executive of Tower Health and of the entity created to own St. Christopher’s.

The surgery program Moulick heads was closed for an internal review for a period in 2016 and 2017. Later, state regulators found that the hospital did too little to investigate nine infant deaths after heart surgery. It’s not clear if that history was a factor in the decision not to assume Moulick’s contract.

In approving the sale, Gross said the buyers are the type the community wanted. “They are local. They are nonprofit.”

Under the sale agreement, the $50 million deal must close by Dec. 13, but it could happen sooner.

Staff writer Tom Avril contributed to this article.