Barcelona and Germany goalkeeper Marc-André ter Stegen faces months on the sidelines after the Spanish top club confirmed on Monday that he has suffered a severe knee innjury and will undergo surgery later in the day. “Tests carried out on the first team player Marc ter Stegen confirm that he has a complete rupture of the patella tendon in his right knee,” Barca said on their website. “On Monday afternoon he will undergo a surgical process and once complete a new update will be released.” Spanish news reports said that ter Stegen could be sidelined for eight months. Ter Stegen, 32, came down o…