Patent ID: 11957386
Assignee: nan
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 21:
22. A method of assembling a pivotal bone anchor assembly configured to secure an elongate rod to a bone of a patient via a closure top, the method comprising:
top loading an insert into a channel of a receiver, the receiver including a lower body defining the cavity with a bottom opening and a pair of upstanding arms extending upward from the lower body with opposed interior surfaces forming the channel and configured to receive the elongate rod therebetween, the interior surfaces including a discontinuous helically wound guide and advancement structure configured to interface with the closure top, the receiver further including at least one retaining recess with a downwardly-facing surface below the helically wound guide and advancement structure, the lower body including a cavity in communication with the channel and the bottom opening, the cavity partially defined by a partially spherical-shaped internal surface adjacent the bottom opening; and
downwardly displacing the insert within the channel such that:
at least a portion of the insert is first deflected inwards with respect to the receiver and then allowed to resiliently deflect back outwards; and
a radiused outer surface of at least one lateral projection of the insert snaps into the at least one retaining recess under the downwardly-facing surface to prevent upward movement of the insert within the receiver, the insert including an upper surface configured to engage the elongate rod when the elongate rod is received between the pair of upstanding arms;

positioning an upper end portion of a bone screw into the cavity of the receiver, the bone screw including a threaded lower portion opposite the upper end portion, the upper end portion having a capture structure with a partially spherical-shaped lower surface that extends radially outward and axially upward relative to the threaded lower portion; and
establishing sliding engagement between the partially spherical-shaped lower surface of the capture structure with the partially spherical-shaped internal surface of the cavity of the receiver so as to make possible pivotal motion of the shank with respect to the receiver.