ConforMIS Inc. raised $50 million from a group of private and government investors.

The Burlington partial knee implant maker, which developed technology to manufacture surgical implants and instrument custom-made to patients’ physiology, said the Series D round came from private equity firms led by prior investor Aeris Capital and the sovereign funds of foreign governments including Singapore and Kuwait.

Last month, the company landed CE Mark approval in the European Union for its iDuo partial knee replacement system.