Patent ID: 8177820
Filing Date: 2012-05-15
Classification: A61B

Abstract:
1. A bone plate for attachment to a bone surface, the bone plate comprising: a plate comprising at least one screw hole defining a circular opening through the plate, each screw hole being at least partially surrounded by at least one elastically deformable portion of the plate; and a screw disposed in each screw hole, each screw having a conical head with an upper thread and a shaft with a lower thread, wherein the lower thread has a pitch that is greater than the upper thread; wherein the screw hole has a counterthread for engaging with the screw, and wherein the pitch of the upper thread is more severely tapered than the counterthread so that the head is securely clamped to the plate in an anti-rotational connection when the screw is screwed into the bone surface; wherein screwing the lower thread of the shaft into the bone surface causes the upper thread to engage the counterthread on the screw hole; wherein further screwing the lower thread of the shaft into the bone surface draws the head into the screw hole and widens the at least one elastically deformable portion of the plate without deforming remaining plastic portions of the plate, thereby forming tensile stress that clamps the screw to the plate and prevents unintended rotation of the screw; wherein further screwing the lower thread of the shaft into the bone surface increases the tensile stress in the plate around the at least one screw hole as the head is brought flush with the plate.