Patent attributes
A pin allows for convenient and noninvasive adjustment and tightening relative to the bone to correct and/or avoid loosening of the pin and attached external fixator. In one embodiment, the pin includes a shank extending from a head toward a distal tip end of the pin. Adjacent to the distal tip of the pin is a threaded region with a varying pitch and the shank of the pin is tapered or conical having an increasing minor and/or major diameter along the pin from the tip end. In an alternative embodiment, an anchor is provided on the distal tip for engagement with the far cortex of the bone. The anchor includes a tapered region proximate the tip that decreases in diameter. A split ferrule, expansion bushing or collar is seated on the tapered region. The shank of the pin also includes a threaded region on which a washer and nut are engaged for rotational movement longitudinally on the shank. The pin is initially inserted through a hole in the bone so that the tapered region adjacent the distal tip projects through the distal edge of the bone and the expansion ferrule is seated within the far cortex of the bone. The ferrule advances along the tapered region and expands to securely seat within the far cortex of the bone for anchoring the external fixator. In either embodiment, subsequent to initial pin installation into the bone, if the pin becomes loose relative to the bone, additional rotation of the pin re-establishes a secure pin-bone interface.
