Sentence:  However, <WSD>polyaxial</WSD> screw heads can be controlled with an instrument in such a way as to mimic the monoaxial screw capability for direct vertebral rotation but ultimately retain the advantages of a <WSD>polyaxial</WSD> screwssic. / The <WSD>polyaxial</WSD> screw is the most versatile. The <WSD>polyaxial</WSD> screw is a load-sharing device. A portion of the applied correction force is dissipated through the <WSD>polyaxial</WSD> connection protecting the bone-screw interface. 
Meaning of the word marked with <WSD> tags:  Having more than one axis.