| 摘要 |
A bone penetrating pin for medical use includes, in one embodiment, a shank provided at one end with a bone penetrating element of titanium or single crystal alumina ceramic material, and a driving head at the other end. A removable cap is applied to the driving end, the cap including upper and lower cylindrical portions of substantially identical diameters interconnected by an intermediate portion of substantially smaller diameter. The upper portion is formed with oppositely extending arms for application of torque through the cap to the shank and bone penetrating element. The intermediate portion of the cap is designed to fail in shear upon the application of torque in excess of a predetermined maximum; that is, it provides a torque limiting function. In another embodiment, the torque applying and limiting means are in the form of a tool assembly comprising a shank engageable with one end of a bone penetrating pin, and a cap slidable with respect to the shank, wherein a torque limiting insert is receivable between the cap and the shank to drivingly couple the two. More specifically, the tool of this second embodiment includes an elongated shank provided with a pin fastener engaging tip at one end and a first socket formed at the other end. A torque applying device is slidably mounted with respect to the shank, and includes a second socket substanially aligned with the first socket. A torque limiting insert is receivable within the first and second sockets to couple the torque applying device and the pin engaging shank.
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