Many different mechanisms have evolved over the years for targeting distal femoral screw holes. Nearly all of these techniques are x-ray dependent. We describe the first practical use of magnetic distal targeting to accurately target distal screw holes. The procedure involves the use of neodymium-iron-boron magnets, which are placed at the level of the distal screw holes to be targeted, and the accurate placement of a cannulated guide wire by use of a free-floating balanced magnet encased in a soft tissue protector. Once magnetic alignment has been achieved, a compass drive advances a 1.6-mm Steinmann pin into the outer cortex of the bone. The target magnet is withdrawn up the femoral canal and a cannulated drill is used to overdrill the guide wire to prepare the screw hole within the intramedullary nail. The length is measured and the screw is inserted. This technique has proven to be accurate with first-time users, and in surgical situations, it reduces x-ray exposure and operative time.
Address correspondence and reprint requests to Alfred A. Durham, MD, Orthopedic Surgery of Roanoke, 2110 Carolina Ave., SW, Roanoke, VA 24014.
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