POLYAXIAL PEDICLE SCREW

摘要

A polyaxial pedicle screw comprises a screw base (1), a screw head (2), and a compression ring (5). The screw base (1) is tubular. Two U-shaped openings (11) are disposed on a side wall at one end of the screw base (1). A convex ridge (12) is disposed at an opening at the other end of the screw base (1). A snapping slot (13) is disposed on an inner wall of the screw base (1). The screw head (2) comprises a rod body (20) and a spherical structure (21) fixed at an end of the rod body (20). The spherical structure (21) is located in the screw base (1) and contacts an inner side of the convex ridge (12), and an outer diameter of the spherical structure (21) is greater than an inner diameter of the convex ridge (12). Two symmetrical bumps (51) are disposed on an outer wall at an end of the compression ring (5), and the compression ring (5) is disposed in the snapping slot (13). The compression ring (5) contacts the spherical structure (21), and an inner diameter of the compression ring (5) is greater than the outer diameter of the spherical structure (21), so that the spherical structure (21) is rotatablely fixed between the snapping slot (13) and the convex ridge (12). According to the polyaxial pedicle screw of the present invention, the convex ridge (12) on the screw base (1) snaps the spherical structure (21) of the screw head (2) in the screw base (1). As the screw base (1) is not elastically deformed, the problem caused by elastic snap strength in the polyaxial pedicle screw in the prior art is avoided.