Troublesome knee sidelines Dragons' Masoe

St George Illawarra's Mose Masoe has been sidelined indefinitely by another injury to the knee that kept him out of this year's NRL season.

The front-rower has gone under the knife to clear out a 'cyclops lesion' in his right knee.

The 27-year-old Samoan international has not played for the Dragons since his recruitment from Super League club St Helens at the end of 2015 after rupturing his ACL in February this year.

The club said Masoe, who has played 63 NRL games, turned up to pre-season training clearly inhibited.

"Mose was still working through some troubles with his knee," Dragons head of athletic performances Nathan Pickworth told the club's website.

"Over the break, he came in on his own bat and wanted to do a running session.

"It appeared there was a mechanical problem there (in his knee).

"We feel this (surgery) is a mechanical solution to a mechanical problem and that will restore his range of motion in his knee."

The New Zealand-born enforcer starred in his two years in the Super League after stints with the Sydney Roosters and Penrith.