Scans on Tuesday revealed the 32-year-old will need surgery to repair a small tear in his achilles and to remove a bone spur on his heel.

Bosschaart had surgery on an achilles problem at the end of last season but it's understood the current injury is not related.

It's a cruel blow for the Sky Blues who took the first step towards reviving their season by beating Melbourne Heart on Sunday.

With a potential finals berth all of a sudden back on the agenda, Sydney coach Frank Farina could delve into the market to find a replacement in the January transfer window.

Bosschaart is expected to undergo surgery on Thursday and will undertake a six month rehabilitation program. The shattered defender took to Twitter on Tuesday afternoon to reveal his season was over.

"Gonna hold me on the sidelines for at least 6 months again," the Dutchman wrote.

"So a sad day for me. I will getting back harder and stronger."

After his long rehabilitation from his previous achilles injury, Bosschaart has managed just six appearances for the Sky Blues this season in a difficult season for the club.

Sydney medical staff were hopeful of trying to ease Bosschaart through the rest of the season by managing the problem but following further scans surgery was the only option.

"It's definitely a blow for us but we will push on with the players who have been getting the job done in recent weeks," Farina said.

"Pascal is an experienced player and we will miss that experience as we move towards the business end of the season.

"It is a shame he picked up the injury as he was looking good after such a long layoff from the injury he suffered last year."

This recent setback will cast serious doubts over the playing future of the veteran defender, who still has another year to run on his Sydney contract.

The Sky Blues possess the worst defence in the A-League, conceding 33 goals in 16 goals this season and with fellow centre-back Adam Griffiths also currently on the sidelines, Farina is likely to look for reinforcements before the transfer window closes.

Teenager Aaron Calver, utility Rhyan Grant and Trent McClenahan have all been used in the troubled central defensive position throughout this campaign.

The Sky Blues host struggling Wellington at Allianz Stadium on Saturday night and could move into the top six with a victory.