Biomechanical comparison of two implant head elements for screw-blade anchorage in the femoral head
Proximal femoral fractures are the most common fractures in patients older than 65 years, being accompanied by high complication rates ranging up to 35% for femoral neck fractures and up to 15% for trochanteric ones. Despite the variety of existing implant systems, their treatment is still challenging. The screw-blade implant systems, being a combination of a lag screw and a blade adding rotation stability to the femoral head, offer a new approach for improvement of the osseous purchase, especially in osteoporotic bone.
To compare biomechanically the head element (HE) anchorage of 2 screw-blade implant systems in the femoral head.
Twenty paired human cadaveric femoral heads were assigned to 4 groups (n=10), implanted with either Rotationally Stable Screw-Anchor (RoSA) HE or Gamma3 Rotation Control Lag Screw (U-Blade) in center or off-center position, and biomechanically tested under progressively increasing cyclic axial loading at 2 Hz. U-Blade revealed better femoral head anchorage in center position compared to RoSA HE. On the other hand, RoSA HE seems to react less sensitive to suboptimal screw insertion in off-center position than U-Blade.
Knobe M (Prof), Cantonal Hospital Lucerne, Switzerland