As outlined by Marca, the shot-stopper sustained the injury in a training session last Friday and there has been no reduction in the pain or concern, with further tests indicating that surgery was necessary.
The Dutch goalkeeper had the operation this week and told reporters, as per Marca: “The operation was great. Happy to return home. Now is the time to begin recovery.”
The medical intervention was intended to repair the fibre breakage in the thigh and to help regenerate the muscle so that there are no risks of a new break in the area.
Cillessen, 31, spent five seasons at Ajax between 2011 and 2016 before a €13m move to the Camp Nou, but he played second fiddle to Marc-Andre Ter Stegen and transferred to the Mestalla last summer.
Cillessen moved to Los Che in a €35m deal while Neto went the other way for €26m plus €9m in variables and he featured in 24 La Liga games last campaign, but has been number two to Jaume Domenech this season.