Patent ID: 9168069
Filing Date: 2015-10-27
Classification: A61B

Abstract:
1. In a bone anchor, the improvement comprising: a) a shank having a body for fixation to a bone and an integral upper portion having a convex substantially spherical first surface with a first radius; b) a receiver having a base and a pair of upright arms forming an open channel, the base defining a chamber and having a lower opening, the channel communicating with the chamber; c) an insert located within the receiver, the insert having first and second lower inner surfaces, the first inner surface directly engaging the shank upper portion; and d) a resilient open retainer captured within the chamber and expandable about the shank upper portion, the retainer having a body and an upwardly extending super-structure, the body partially defining an inner edge, the insert second lower inner surface pressing the super-structure against the shank upper portion resulting in a friction fit between the retainer and the shank upper portion during non-locking angular manipulation of the shank with respect to the receiver and the inner edge frictionally engaging the shank first spherical surface during final locking of the shank with respect to the receiver with the retainer being in expansion-only locking engagement with both the shank upper portion and the receiver and the insert first inner surface being frictionally locked against the shank upper portion.