Portland Thorns midfielder Tobin Heath still remains sidelined more than six weeks after suffering a back injury.

When Heath originally suffered the back injury in preseason, it was classified as minor. But the midfielder's timeline to return to play has consistently been extended as she has tried to work her way back from the lingering injury over the last month and a half.

Thorns coach Mark Parsons said Tuesday that Heath would be out another 2-3 weeks and could make her return when the Thorns host the Boston Breakers on May 27.

"We're hopeful that Tobin and Katherine (Reynolds) could be available for that game, but we won't know that for another week or so," Parsons said.

Along with Heath, Reynolds (left groin strain), Dagny Brynjarsdottir (back sprain) and Mana Shim (left foot sprain) are all working their way back from injuries and are expected to miss the next 2-3 weeks.

Parsons said that while both Heath and Reynolds could return in time for the game against Boston on May 27, Brynjarsdottir and Shim were a bit behind Heath and Reynolds in their recoveries.

But Parsons also said that the timelines for Heath and Brynjarsdottir have been particularly tough to predict because back injuries are difficult.

"There's so many things connected to your back and the muscles and we're trying to be ultra, ultra safe and at the same time, we need the players," Parsons said.

The injuries have forced Parsons to shuffle his lineup in the first four games of the season, but the Thorns have managed to go 2-1-1 to open the year.

"It's frustrating, but I can only get frustrated for a few second because I've got a job," Parsons said. "Okay, they're not available. With everyone else, we got to win a game."

-- Jamie Goldberg | jgoldberg@oregonian.com

503-853-3761 | @jamiebgoldberg