Patent ID: 7670341
Filing Date: 2010-03-02
Classification: A61B

Abstract:
1. A bone fixation assembly comprising: a side plate configured to be mounted on a bone and having a hole therethrough, the hole including a first detent portion and an inner ledge, the first detent portion and the inner ledge protruding into the hole at different locations in the hole; a barrel insertable into the hole and having a bore therethrough for placement of a portion of lag screw, the barrel including an upper portion having an external ledge and a second detent portion, the external ledge being a protrusion from the upper portion of the barrel that extends at least partially around a circumference of the upper portion of the barrel substantially perpendicular to the longitudinal axis of the barrel and configured for engagement with the inner ledge of the hole; and a mechanical spring for biasing the second detent portion into a locking position with the first detent portion for angularly locking the barrel in relation to the side plate; wherein the barrel further comprises a lower portion configured to pass through the hole prior to the upper portion, and wherein the mechanical spring is located on the upper portion of the barrel such that when the barrel is inserted within the hole and the external ledge on the upper portion of the barrel is engaged with the inner ledge in the hole, rotation of the barrel from a first position to a second position forces the second detent portion against the first detent portion compressing the mechanical spring in a direction toward the lower portion of the barrel, and continued rotation of the barrel from the second position to a third position allows the mechanical spring to be released and bias the first detent portion in a direction away from the lower portion of the barrel into a position adjacent the first detent portion thereby angularly locking the barrel with the side plate.