Uniondale-based Professional Physical Therapy said Monday that private equity firm Thomas H. Lee Partners has taken a stake in the company.

The rapidly expanding outpatient physical therapy provider operates 107 centers in New York, New Jersey and Connecticut. It has 24 clinics on Long Island, 14 of which are in Suffolk County, the company said in a news release.

It held a grand opening on Monday for its newest location, at 800 Veterans Memorial Hwy. in Hauppauge.

Future expansion by the company will mostly focus on the tristate area, although growth into contiguous states is possible, said Adam Elberg, chief executive and president of Professional Physical Therapy.

“We don’t want to hop all over the country,” he said.

The deal comes as the health care market grows on Long Island, driven by more widespread access and an aging population. Health care and social assistance jobs grew 4.4 percent year-over-year to 222,600 through November, according to the New York State Department of Labor.

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Professional Physical Therapy did not disclose the size of the deal with Boston-based Thomas H. Lee Partners. The private equity firm, which has raised more than $20 billion of equity capital since 1974, also didn’t comment on the deal.

But Elberg said that he remains the “single largest investor.” More than 100 employees are also shareholders, he said.

The company has grown rapidly through acquisitions of smaller therapy practices, some of which may find it difficult to stay up to date with regulations. In evaluating businesses to acquire, “We are looking for people who are really exceptional as physical therapists,” Elberg said.

Professional Physical Therapy was founded in 1998, and started to rapidly expand in 2011 when it grew from 10 locations to 107 after it partnered with Greenwich, Connecticut-based private equity investor Great Point Partners.

Great Point Partners said Monday that it was exiting its deal with Professional Physical Therapy.

“Our partnership began five years ago when [Professional Physical Therapy] operated only 10 facilities in a single state and had approximately 300 employees,” said Adam Dolder, managing director at Great Point Partners, in a news release, adding that the company now serves patients in more than 100 locations and employs more than 1,200 people.