A biocompatible implant for a method of treating a reflux disease in a patient by preventing the cardia sphincter from sliding through the patient's diaphragm hiatus opening into the patient's thorax, so as to maintain a pressure support from the patient's abdomen that supports the patient's cardia sphincter. The biocompatible implant has a rigid shape, a circumference of at least 15 mm and is configured to be introduced into the patent's abdomen through a trocar, be fully invaginatable in the patient's fundus wall, and function as an implantable movement restricting device preventing the cardia sphincter from sliding through the patient's diaphragm, when implanted.