This is the fourth time the 19-year-old has had a problem in that area. He suffered a separation, an injury to the junction between the collarbone and the left shoulder, in 2006.
Walcott then had surgery last October on a congenital fault from his father, Don, that left him with weak ligaments in the same shoulder.
He then took a knock to the right shoulder in the defeat at Stoke and Nicola Maffulli, Professor of Sports and Exercise Traumatology at St Bartholomew's Hospital in London, believes the problem will blight the rest of his career.
He told the London Evening Standard: "It will be a question of managing it for the rest of his career. There is always the possibility that other structures around the shoulder have been affected.
"Seeing as he has dislocated his shoulder, it is highly likely that the problem would be related to his old injury. During his period out, he will still be training but avoiding situations where he would be suffering another knock."