The invention relates to a cap-shaped implant for implanting on a prepared stump of a femoral head. The implant is in the form of a ball section (11), having a flat base surface (13) and a polar axis (15) which is arranged in a perpendicular in relation to the base surface (13). According to the invention, a cavity (17) is arranged in ball section (11) which protrudes from the base surface (13), said cavity (17) is rotationally symmetrical and comprises a hollow spatial axis (19) which is arranged below an angle (a) which is different form zero in relation to the polar axis (15).