According to our friends at Mass High Tech:

Relievant Medsystems Inc., a California-based medical devices company, has raised $20 million in venture funding from investors led by Morgenthaler Ventures, which has an office in Boston.

The funding is a Series C round that also included Emergent Medical Partners, Onset Ventures and Canaan Partners, which has a location in Westport, Conn. Relievant, which makes medical devices to treat chronic back pain, has previously raised $9 million in funding. Morgenthaler partner Hank Plain will join Relievant’s board of directors.