| 摘要 |
<p>A polyaxial bone screw assembly includes a threaded shank body integral with an upper capture structure and a head having an inner cavity for receiving the capture structure. The capture structure is threaded and the head includes a threaded opening for rotatable assembly with the capture structure and eventual locking frictional engagement between the capture structure and the head. The head has a U-shaped cradle defining a channel for receiving a spinal fixation rod. The head channel communicates with the cavity and further with the threaded opening that allows for loading the capture structure into the head but prevents pushing or pulling of the capture structure out of the head. The capture structure and the head provide a ball joint, enabling the head to be disposed at an angle relative to the shank body. The capture structure includes a tool engagement formation and gripping surfaces for non-slip engagement by a tool for driving the shank body into bone.</p> |
