External fixation system with radio frequency shielding
AssigneeDePuy Synthes Products, Inc.
InventorsJohn Disegi, Thomas Joseph Maughan
Life of this patent
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Abstract
An electrical insulator is applied to a bone anchor, for instance of a bone implant, such as an external fixation frame, so as to prevent undesirable temperature increases in the bone anchor and surrounding anatomical tissue when subjected magnetic resonance imaging.
Claims21
An external fixation system comprising:
- a first external fixation bone anchor including a first shaft defining a first external surface that is devoid of threads, the first external fixation bone anchor screw further including a first threaded region that extends from the first shaft, the first threaded region presenting external threads that are configured to be anchored into bone;
- a second external fixation bone anchor screw defining a second shaft having a second external surface that is devoid of threads, the second external fixation bone anchor screw further defining a second threaded region that extends from the second shaft, the second threaded region presenting external threads that are configured to be anchored into bone;
- at least one support rod comprising an electrically conductive material;
- and
- a first clamp configured to attach to both the first shaft and the at least one support rod, and a second clamp configured to attach to both the second shaft and the at least one support rod, thereby fixedly supporting each of the first and second external fixation bone anchor screws relative to the at least one support rod,
- wherein at least the first external fixation bone anchor screw comprises a layer of electrically insulative material attached to at least a portion of the first external surface and is not attached to the first threaded region.
A method of fabricating an external fixation system of the type having first and second Schanz screws each including a shaft that defines an external surface that is devoid of threads, and a threaded region that extends from the shaft, the threaded region presenting external threads that are configured to be anchored into a first bone segment, the method comprising the steps of:
- applying a layer of electrically insulative material to at least a portion of the external surface of the first Schanz screw, such that the layer of electrically insulative material is attached to the threaded region of the first Schanz screw.
A method of imaging a region of human anatomy, the region including long bone, the method comprising the steps of:
- placing the human anatomy into an interior of an MRI tube having a magnetic field of approximately 1.5 Tesla, wherein the human anatomy comprises a long bone to which respective threaded regions of first and second Schanz screws are anchored, each of the Schanz screws attached to at least one support rod via respective first and second clamps, wherein the Schanz screws each include an unthreaded electrically conductive shaft extending from the threaded regions, and an electrically insulative tape wrapped around at least a portion of the shafts;
- and
- directing radio frequency pulses into the interior of the MRI tube, such that the threaded regions of the Schanz screws do not increase in temperature by more than six degrees Celsius.
Dependencies are inferred from the claim text.