A femoral component of a hip endoprosthesis includes a lateral supporting wedge designed to be supported by the proximal lateral femur when in use. The wedge can be an integral part of the material of the femoral component or it can be placed on a standard component by cementing or preferably by a male/female socket fit. The lateral surface of the wedge forms an angle of about 10.degree.-20.degree. with the midline of the distal portion of the stem and has an anterior-posterior width of about 8.30 mm, preferably about 10-20 mm, and a medial-lateral extension of the lateral surface of the stem of at least 10 mm, preferably 10-30 mm. An apparatus for testing the endurance of femoral components includes a cable corresponding to the ilio-tibial band. Such an apparatus more accurately models hip biomechanics and thus permits a more accurate test of the stresses on femoral component designs.