Patent ID: 8663298

Claim:
An assembly configured to be connected to an elongated spinal rod, the assembly comprising: a body that is elongate along a longitudinal axis, the body including an upper end with an upper opening, a lower end with a lower opening, the body defining a bore that is elongate along the longitudinal axis and disposed between the upper and lower openings, the bore defining a first diameter proximate the upper opening and the bore further defining a rod-receiving channel extending from the upper end toward the lower end, the rod-receiving channel disposed along a channel axis that is oriented substantially perpendicular to the longitudinal axis, the bore at least partially defined by a lower edge portion of the body, the lower edge portion of the body defining a first curved inner surface that forms a first spherical undercut disposed proximate the lower end, the bore further at least partially defined by an enlarged diameter portion of the body, the enlarged diameter portion of the bore defining a second curved inner surface that forms a second spherical undercut, wherein the second spherical undercut is spaced toward the upper end from the first spherical undercut, the bore has a second diameter at the first curved inner surface of the lower edge portion, and the bore has a third diameter at the second curved inner surface of the enlarged diameter portion, the third diameter is larger than the first diameter, and the first diameter is larger than the second diameter; and a collet defining a cavity that is sized to receive a head portion of a bone anchor and including an expandable portion that is expandable to accept the head portion of the bone anchor and compressible to secure the head portion of the bone anchor relative to the collet, wherein the collet is configured to move within the bore between a loading position, where the expandable portion is proximate the enlarged diameter portion, thereby allowing the head portion to move within the cavity, and a locked position, where part of the expandable portion is in line contact with at least a portion of the first curved surface and the expandable portion is compressed against the head portion such that the head portion is unable to move within the cavity.