Although Newcastle's boss Alan Pardew is waiting on results, he thinks the defender could be out for four weeks.
Meanwhile, Santon has been contacted by Russian side Zenit St Petersburg regarding a possible summer transfer, according to talksport.
Santon's agent, Renzo Contratto has been quoted in Izvestia.ru as saying: "We have spoken several times with Zenit about Santon, but he is focused on the end of the season with Newcastle.
"I do not know what will happen in the summer, but I believe the club will not let him go for less than a certain amount."
Source: Newcastle United Mad