The highly rated Walker, who joined the Hammers from Walsall earlier this summer, will need an operation.
Manager Alan Pardew told the Evening Standard “It's a blow. We need to sign a goalkeeper on loan as a matter of urgency.”
In other news, Stoke City’s Director of Football, John Rudge has confirmed that Hammers Striker Bobby Zamora is a transfer target. Rudge said, “Zamora is one of several players we have been looking at lately.”
It is thought Alan Pardew might allow Zamora the chance to leave Upton Park in order for him to strengthen other areas of his squad.