Boston private equity firm Audax Group is buying Katena Products, which provides instruments to physician offices.

Katena, headquartered in Denville, New Jersey, also provides products to hospitals and surgical centers. The company supplies surgical instruments and single-use devices.

The business was sold by the Cortec Group, a New York private equity firm that bought it in 2009. Cortec focuses mainly on health care companies, and has more than $2 billion in capital under management.

Audax focuses on making middle-market deals has has about $6 billion in assets under management. The firm's recent investments include wire and cable connector business TPC Wire & Cable Corp., in May, and AllOver Media, an advertising company, in March.  For more on the firm, watch our recent video interview with Jay Jester on the state of middle-market M&A.

William Blair & Co. advised Katena on the deal, and Kirkland & Ellis LLP was Audax' legal counsel.

Other recent medical device transactions have come from Cardinal Health, which agreed to buy cardiology and endovascular device maker Cordis from Johnson & Johnson in March, and Shore Capital's acquisition of Summit Medical, which makes surgical and other products, in February.