Polyaxial bone anchoring device

摘要

A polyaxial bone anchoring device is provided including an anchoring element (2, 2', 2", 2"') having a shaft (3, 3', 3", 3"') for anchoring in a bone and a head (4, 4', 4", 4"'), a receiving part (5, 5', 5", 5'") having a top end (51, 51', 51", 51"') and a bottom end (52, 52', 52", 52'''), a channel (56, 56', 56", 56"') for receiving a rod therein and a passage (53, 53', 53", 53"'; 54, 54', 54", 54"'; 55, 55', 55", 55'") extending from the top end (51, 51', 51", 51'") to the bottom end (52, 52', 52", 52'") and including a seat (54, 54', 54", 54"') for receiving the head (4, 4', 4", 4"'), a pressure element (6, 6', 6", 6"') which is arranged in the passage (53,53',53",53''') and configured to exert pressure onto the head (4, 4', 4", 4'''), wherein the head is pivotable with respect to the receiving part (5, 5', 5", 5"') and can be locked at an angle by means of the pressure element (6, 6', 6", 6"'). The pressure element (6, 6', 6", 6"') comprises at least one hole (600a, 600a', 600a", 600a"'; 600b, 600b', 600b", 600b"'). The receiving part (5, 5', 5" ,5"') includes at least one threaded through hole (500a, 500a', 500a", 500a"'; 500b, 500b', 500b", 500b'") for receiving a set screw (8, 8', 8", 8"'), and at least one set screw (8, 8', 8", 8"'). The through hole (500a, 500a', 500a", 500a"'; 500b, 500b', 500b", 500b"') and the hole (600a, 600a', 600a", 600a"'; 600b, 600b', 600b", 600b"') are arranged such that by screwing in the set screw (8, 8', 8", 8''') into the through hole (500a, 500a', 500a", 500a'''; 500b, 500b', 500b", 500b"') and engagement of the set screw (8, 8', 8", 8"') with the hole (600a, 600a', 600a", 600a"'; 600b, 600b', 600b", 600b"') a force is exerted by the pressure element (6, 6', 6", 6''') onto the head (4, 4', 4", 4"') that maintains the head at an angular position by friction before locking the polyaxial bone anchoring device.