| 摘要 |
A polyaxial bone screw includes a shaft, a body member, and a toroidal member. The shaft includes a longitudinal axis and a proximal end with a head having a generally rounded surface. The body member has a bore disposed longitudinally therethrough and a groove defined by a luminal surface of the bore. The toroidal member has an elliptical cross-section with a major axis and disposed within the groove to engage the generally rounded surface of the head at a point of contact. |
