A trial implant system comprising: a rod component (120, 220, 320, 680, 740) that has a neck (122, 222) that includes a free end (124, 224), the neck has a longitudinal axis of the neck (123)； a first test head (100, 200, 490, 660, 720) having an articulation surface (102), the first test head that includes a hole (108, 208, 498, 725) that has a longitudinal axis hole (106, 206) and which can receive the free end of the neck with the longitudinal axis of the neck and coincident of the longitudinal axis of the hole； a first formation (136, 134, 234, 236, 504, 506, 566, 568, 586, 588, 604, 606, 656, 682, 684, 722, 724)； and a plurality of second formations (110, 112, 210, 212, 499, 662, 664, 742, 744), in which one of the first formation and the plurality of second formations is provided in the neck and the other is provided inside the hole and in which each of the second formations can be fitted coincidentally with the first formation of limiting the depth of neck insertion in the hole by a different amount, characterized in that the plurality of second formations are arranged angularly around the longitudinal axis and the first formation and the plurality of second formations are slidably coupled when the first test head is removed or separated from the stem component by translation along the longitudinal axis.Un sistema de implante de ensayo que comprende: un componente de vástago (120, 220, 320, 680, 740) que tiene un cuello (122, 222) que incluye un extremo libre (124, 224), el cuello tiene un eje longitudinal del cuello (123)； una primera cabeza de ensayo (100, 200, 490, 660, 720) que tiene una superficie de articulación (102), la primera cabeza de ensayo que incluye un orificio (108, 208, 498, 725) que tiene un eje longitudinal orificio (106, 206) y que puede recibir el extremo libre del cuello con el eje longitudinal del cuello y coincidente de eje longitudinal de orificio； una primera formación (136, 134, 234, 236, 504, 506, 566, 568, 586, 588, 604, 606, 656,
