FIELD: medicine.SUBSTANCE: bone screw with adjustable length for use in a surgical operation, in which the screw is inserted into the bone, contains a screw head and a rod. Head of the screw extends from the proximal end to the distal end and has an outer surface. Screw head and the rod pass along the longitudinal axis. Stem has an outer surface of the stem and extends between the distal end of the screw head and the distal tip. Outer surface of the screw head has the largest diameter measured along the first direction perpendicular to the longitudinal axis, which is greater than the largest diameter of the outer surface of the rod measured along the first direction. Plurality of threaded portions are disposed at discrete positions along the rod and a plurality of non-threaded portions are disposed at discrete positions along the rod. Threaded sections are longitudinally separated by threads without threads. Threaded portions comprise a series of turns extending at least partially around the circumference around the rod. Each of the plurality of threaded portions has at least two cutting grooves formed by a recess formed radially in the screw shaft and extending longitudinally along the length of the threaded portions such that the turns of the threaded portions are formed into at least two discontinuous thread segments extending along the circle around the rod. Plurality of non-threaded portions are narrowed longitudinally along the shaft in the proximal-distal direction. Plurality of threaded portions proximally adjacent to a plurality of tapered, threadless portions comprise at least one thread turn narrowed at the same angle as the narrowing of the adjacent non-threaded portion. Set of adjustable-length bone screws for use in a surgical operation, in which the screws are inserted into the bone, comprises a plurality of the above-mentioned bone screws with an adjustable length. Each of the adjustable-length bone screws has an initial length formed by the distance
