Patent ID: 8197517

Claim:
A polyaxial screw assembly, comprising: a screw comprising a screw head that is bulbous and a screw shaft having external threads; a receiver pivotable with respect to said screw head; and a collet interposed between said screw head and said receiver, said collet having an upper end and a lower end opposed to said upper end; wherein said polyaxial screw assembly is capable of existing in a non-locked condition, wherein in said non-locked condition, a first radially-inwardly-facing surface of said receiver exerts a first force on said collet at an upper external touching point at said upper end of said collet; and wherein a second radially-inwardly-facing surface of said receiver exerts a second force on said collet at a lower external touching point on said collet adjacent said lower end of said collet; and wherein between said upper external touching point and said lower external touching point there is a non-contact region in which there is no contact between an exterior of said collet and said receiver; and wherein an outwardly-facing surface of said screw head exerts a third force on said collet at an interior contact point located on an interior of said collet between said upper external touching point and said lower external touching point.