Massachusetts-based Intrinsic Therapeutics is nearing the close of a $20.9 million equity round, with about $17.3 million raised so far.

The round has been open less than a month and has garnered the interest of 28 unnamed backers, according to a September 17 SEC filing.

Intrinsic’s flagship device is the Barricaid, an adjunct for lumbar limited discectomy to replace missing or damaged parts of the anulus to prevent re-herniation, disc collapse, the return of sciatica and potentially to help stave off low back pain.

The device is available in 3 sizes (8mm, 10mm and 12mm) and comes pre-loaded on a disposable delivery instrument, according to the company’s website.

Intrinsic is looking for about $3.6 million to close its equity funding round.