The prosthetic foot (1) is a lamina of composite material with a characteristic J-shape, fixable by a TT bracket (2) directly to a socket (3) containing the stump, or to a TF bracket (2a) itself fixable to a mechanical knee (G) fixable to a socket (3a). Said socket (3 or 3a) has a main axis (5) defined by the loading straight line by which the user, after applying the prosthesis, discharges body weight in the static position, and passing through a point (4) identifying the femoral epicondyle and coinciding with the centre of rotation of the knee during mid-stance. During assembly and static alignment of the foot (1), with the configuration in which the main axis (5) is in the vertical position, a segment (9) joining a first point (7) of tangency between said foot (1) and a line pertaining to a plane (6) perpendicular to the main axis (5) and defining the ground line, to a second point (8) of tangency between the foot (1) and a straight line (10) parallel to the main axis, is inclined by an angle ± of between 30° and 50° to said ground line (6), said second point (8) of tangency lying at the end of a segment (11) which is inclined by an angle ² of between 20° and 40° to said main axis (5) and intersects said axis at the point (4).
