Bone anchor, to attach a component to the bone, has a head to hold the component and a shaft with screw thread sections and thread-free sections along the shaft length

摘要

The bone anchor (1), to attach an external component to the bone, has a head (2) to secure the component. The shaft (3), to be anchored into the bone, has a screw thread (5) along a given section of it. Sections (6) are set along the length of the shaft, between the tip (4) and the head, which are without a screw thread. The thread-free surface is closer to the shaft axis, and the shaft can be fitted with two or three thread-free surfaces. The shaft is of a shape memory alloy. The anchor surfaces are roughened and/or coated with hydroxy lapatite to encourage bone growth.