REUTERS: West Ham United defender Ryan Fredericks has undergone right shoulder surgery that will keep him out for around six weeks, the Premier League club said.
The 27-year-old sustained an injury in their 2-0 league defeat to Manchester City last week, his second match since returning from a hamstring problem that had ruled him out for nearly a month.
The Englishman has played 20 league games for the club this season, starting 19 of them.
"Ryan's surgery went exactly as planned and he'll begin his rehabilitation and recovery immediately, with the plan being for him to be available again in early to mid-April," West Ham medical chief Richard Collinge said in a statement.
Czech international midfielder Tomas Soucek, who joined West Ham on loan from Slavia Prague in January, was ruled out for around three weeks with a hip flexor injury.
West Ham, who are 18th in the league standings with 24 points, host Southampton on Saturday.