COMBINED EXTRACTOR FOR DAMAGED BONE SCREWS Russian patent published in 2018 - IPC A61B17/88 A61B17/92 B25B13/44 

FIELD: medicine.

SUBSTANCE: combined extractor contains handle to create the torque, rod adapter and the working head in the form of a cup with opened outwards conical cavity, surface which is equipped with helical ribs with a conic cross-sectional shape, forming the inner long-pitch multiple thread, that are placed axisymmetricly and are consistently interconnected. Radial grooves are made in the head from the side of conical cavities on the same angular distances from each other and from the helical projections, in which figured plate are installed with the ability to move axially, placed in the radial grooves at the end of cylindrical rod that is placed in central holes of the working head and tubular adaptor attached with the other end using elastic corrugated cylinder (bellows) to the handle and being the anchor of electromagnet (solenoid) of AC, stator of which is attached flange of tubular adaptor and contains radial cylindrical dowels, forming a bayonet connection with figured cuts in the cylindrical handle collar, covering on the outside generatrix the stator of electromagnet. Sides of figured plates, turned inside of conical cavity of working head, has angle of slope equal to the angle of slope of conical surface cavity, and equipped with cutting elements in form of teeth, similar to teeth of outer one-row spline broach, cross-sectional shape of which conforms to the cross-section shape of helical ribs.

EFFECT: reduced duration of surgery, avoidance of need to create large axial effort and moments needed for helical ribs cut in screws material with the aim of creating the indentations of required sizes, allowing to transmit torque to turn damaged screws without cutting used ribs.

10 dwg