Zyga Technology said it raised $2 million in an equity-and-options round it hopes will eventually bring in $5 million.
Four unnamed investors participated in the round, according to a regulatory filing.
Based in Minnetonka, Minn., Zyga develops minimally invasive surgical products for the treatment of lumbar spinal conditions.
In December 2013, Zyga reported raising $10 million in a funding round involving 5 undisclosed investors.
Zyga last year closed enrollment in the Glissade study, a 40-patient clinical trial of its Glyder facet resurfacing system in treatment of chronic back pain. The device maker hopes to use the results of the study to win an investigational device exemption from the FDA and CE Mark approval in the European Union.