A medical device for implantation in a knee joint of a human patient is provided. The medical device comprises: an inner surface (130, 1707) and an outer surface (131, 1704). The inner surface comprises: a first point (121), a second point (124), a third point (122), a fourth point (125), a fifth point (123), and a sixth point (126), all points located on different places along a length axis (132, 1705) of said inner surface. A first straight line (127), reaching from the first point to the second point is parallel to a second straight line (128) reaching from the third point to the fourth point, which in turn is parallel to a third straight line (129) reaching from the fifth point to the sixth point. The first and third straight lines are of equal length and the second straight line is longer than the first, furthermore the third straight line is positioned between the first and third straight lines. Wherein the medical device comprises a first articulating surface (175a) adapted to replace the surface of the contacting surface of the medial condyle, a second articulating surface (175b) adapted to replace the contacting surface of the lateral condyle and a third articulating surface (175c) adapted to replace the contacting surface of the patella.La présente invention concerne un dispositif médical destiné à être implanté dans l'articulation du genou d'un patient humain. Ledit dispositif médical comprend une surface interne (130, 1707) et une surface externe (131,1704). Ladite surface interne comporte les éléments suivants : un premier point (121), un deuxième point (124), un troisième point (122), un quatrième point (125), un cinquième point (123) et un sixième point (126), tous ces points étant situés à différents emplacements le long de l'axe longitudinal (132,1705) de ladite surface interne. Une première ligne droite (127), allant du premier point au deuxième point, est parallèle à une deuxième ligne droite (128) allant du troisième point au quatrième point, qui
