polyaxial

2008, Michael F. O′Brien, Peter O. Newton, 48: Surgical Treatment of Adolecent Idiopathic Scoliosis, Daniel H. Kim, et al. (editors), Surgery of the Pediatric Spine, page 605, However, polyaxial 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 polyaxial screws. The polyaxial screw is the most versatile. The polyaxial screw is a load-sharing device. A portion of the applied correction force is dissipated through the polyaxial connection protecting the bone-screw interface.

2009, George J. Haidukewych, Procedure 25: Treatment of Periprosthetic Femoral Fractures above a Total Knee Arthroplasty, Arlen D. Hanssen, W. Norman Scott, Total Knee Replacement, unnumbered page, More modern, polyaxial designs allow screw angulation prior to end point locking, and these can be very useful if femoral component lugs or the like are encountered during drilling.