Patent ID: 9034022
Filing Date: 2015-05-19
Classification: A61B

Abstract:
1. A surgical screw assembly comprising: a fastener including an elongate shaft having a proximal end and a distal end and a head at said proximal end, said head having an external surface; a tulip having a tulip proximal end, a tulip distal end, an external surface and an internal bearing surface, said tulip distal end having a bore therethrough defining said internal bearing surface and having a diameter dimensioned to allow said distal end of said elongate shaft to pass therethrough; a first step feature located at a distal end portion of said bore and extending inwardly from said bore, said first step feature reducing the diameter of said bore to allow said distal end of said elongate shaft to pass therethrough, but prevent passage of said head therethrough as a portion of said first step feature contacts said external surface of said head; and a second step feature located at a distal end portion of said bore, distally of said first step feature, said second step feature further reducing the diameter of said bore to a dimension less than a dimension established by said first step feature, the further reduced dimension allowing said distal end of said elongate shaft to pass therethrough, but preventing passage of said head therethrough as a portion of said second step feature contacts said external surface of said head and a portion of said first step feature a portion of said first step feature contacts said external surface of said head, wherein, in an unlocked configuration, said external surface of said head contacts said first step feature but does not contact said second step feature.