The present invention relates to a method for preparing and placing, in situ, wedges between a device for protecting the knee joint of a user and the side surfaces of the knee of said skier, including at least one rigid shell (10) including or supporting, on the upper portion (11) thereof, rigid side flanges (11a-11b) extending opposite the side surfaces of the knee, wherein said wedge(s) are applied at least against the inner surface of at least one of said flanges, characterized in that it includes the following consecutive steps: a) positioning at least one empty bag (31) in the space between at least one side surface of the knee and the inner surface of one of said side flanges, said bag consisting of a flexible wall provided with a filling port (31a) and b) injecting or pouring a filling material inside said bag via said filling port (31a) until said wall is in contact with said side surface of the knee and matches the shape thereof, said filling material consisting of a polymer resin that is cross-linkable and thermosets preferably at 10°C to 30°C c) and setting said filling material in situ in the space between said flange and the knee by cross-linking, preferably at room temperature.La présente invention concerne un procédé de préparation et mise en place in situ de cales entre un dispositif de protection de larticulation du genou dun utilisateur et des faces latérales du genou dudit skieur, comprenant au moins une coque rigide (10) comprenant ou supportant, sur sa partie haute (11) des joues latérales (11a-11b) rigides sétendant en vis-à-vis des faces latérales du genoux, la (ou les) dite(s) cales(s) étant appliquées au moins contre la surface interne dau moins une dite joue, caractérisé en ce quil comprend les étapes successives dans lesquelles : a) on positionne au moins 1 poche (31) vide dans lespace entre au moins une face latérale du genou et la surface interne dune dite joue latérale, ladite poche étant constituée dune paroi souple munie dun orifice d
