| 摘要 |
A polyaxial bone anchoring device is provided comprising
a bone anchoring element (1) comprising a head (3) and a shank (2), the head having a portion with a greatest diameter (E);
a receiving part (5, 5', 500) for receiving a rod (100) for coupling the rod to the bone anchoring element,
the receiving part (5; 5'; 500) comprising a top end (5a) and a bottom end (5b), a first passage (51) coaxial with a first longitudinal axis (51a) and a second passage (56) coaxial with a second longitudinal axis (56a), wherein the first and second longitudinal axes intersect;
wherein the first passage (51) includes a seat (62, 63; 92) that opens toward the bottom end (5b), the seat being configured to allow pivoting of the head relative to the seat;
wherein the seat (62, 63; 92) is substantially symmetrical with respect to the pivoting of the head when the head pivots in any direction and in the respective opposite direction; and wherein the head (3) is insertable into the seat (62, 63; 92) from the bottom end. |
