Schopper C, Keck K, Zderic I, et al. - In this study, the biomechanical head element (HE) anchorage of two screw-blade implant systems differing in blade orientation in the femoral head – vertical vs horizontal was compared. Researchers assigned 20 paired human cadaveric femoral heads into four groups (n=10), implanted with either Rotationally Stable Screw-Anchor HE (RoSA-HE, vertical blade orientation) or Gamma3 Rotation Control Lag Screw (Gamma-RC, horizontal blade orientation) in the center or off-center position, and biomechanically tested until failure under progressively increasing cyclic loading at 2Hz. The data exhibited that a horizontal blade orientation rather than a vertical one demonstrates a better femoral head anchorage in the center position. The results suggested that the stability of the Gamma-RC drops sharply in off-center position for screw-blade implant systems with a blade oriented in horizontal direction central insertion is the placement of choice.