| 摘要 |
The present invention relates to a torque limiting device for use in the affixation of a halo-type traction tool to the skull of a person. The torque limiting device has a shaft or shank embedded in a handle member which rotatably engages a skull pin during the fixation of a halo-type traction device to an individual. The torque limiting device has a first shear point at a reduced shank intermediate portion which prevents rotational torque forces in excess of a predetermined level from being applied to a skull pin during the attachment procedure of a medical cervical traction brace or tool. The present invention also includes a second shear point at the shank-handle interface which acts as a second safety mechanism to ensure that excessive pressure is not applied, and undesirable skull penetration does not occur, during the attachment procedure of a skull pin and halo to an individual's skull. The torque limiting device further includes a skull pin engaging end. The handle encapsulates a substantial portion of the shank, including the first and second shear points, and a handle-shank interface retaining collar and groove arrangement from which the pin engaging end extends also from the handle. Upon release of the first shear point or the second shear point, the handle and skull pin engaging end may rotate free of each other without separation of the handle from the skull pin engaging end, thereby keeping the device in one piece for easy handling, loss prevention and protecting an individual from risk of injury.
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