The court fight among former partners in 3B Orthopaedics P.C. took a bitter turn this week with a new lawsuit against the University of Pennsylvania and a former partner in the high-profile surgical practice.

3B Orthopaedics was affiliated with Pennsylvania Hospital until this year, when Aria Health bought it and moved its main office to Aria's Bucks County facility in Langhorne.

One of the 3B shareholders, David G. Nazarian, took a job with the University of Pennsylvania Health System instead of moving. Nazarian alleged in a March lawsuit that 3B had refused to pay him his share of the sale proceeds.

The three B's are Robert E. Booth, Richard A. Balderston, and Arthur R. Bartolozzi. Philip M. Maurer is also a 3B surgeon and stockholder. Nazarian was the fifth shareholder.

Nazarian's former partners fired back Wednesday with a lawsuit in Philadelphia Common Pleas Court alleging that Nazarian and Penn had broken the terms of employment and affiliation agreements, and had misappropriated trade secrets.

"The empire strikes back," 3B's attorney, Paul R. Rosen, chairman of Spector Gadon & Rosen, said.

Nazarian in particular was accused of filing a "false, malicious, and defamatory complaint" in March. Nazarian said in the suit that he had been subjected to "multiple instances of deceit, harassment, intimidation, and unethical conduct." That partly explained why he did not want to go to Aria, he said.

In their lawsuit, the three B's deny those allegations and point out that Aria withdrew its offer to hire Nazarian at a $1.875 million annual salary after he took too long to accept it. That information was in a letter, included in the court filing from Nazarian to the three B's.

The suit goes on to belittle Nazarian's accomplishments as a doctor.

"For the most part, Dr. Nazarian's client base does not come from Dr. Nazarian's own name and following, but from the 3B brand and patients contacting 3B, which were then assigned to Dr. Nazarian by 3B."

The lawsuit accuses Penn of a "de facto secret purchase of Dr. Nazarian's 3B practice" and of violating an affiliation agreement by sending 30,000 letters to 3B patients touting Nazarian's decision to stay at Pennsylvania Hospital.

Penn had no comment, spokeswoman Susan Phillips said.

Kerry E. Slade, a lawyer with Klehr Harrison Harvey Branzburg representing Nazarian, did not respond to an e-mailed request for comment.