SCREW FOR OSTEOSYNTHESIS Russian patent published in 1999 - IPC

FIELD: medicine, particularly, surgical methods and tools applicable in orthopedic and traumatologic operations, mainly, under conditions of regional osteoporosis (incoherent porous bone in elderly people bedridden for prolonged time). SUBSTANCE: screw consists of threaded part, neck and head. Threaded part beginning from screw end has outer diameter of 6.5 mm, inner diameter of 3 mm and thread pitch of 2.5 mm with special profile of thread turns and front angle of 5 dwg and rear angle of turn profile of 25 dwg, and passing into thread inner diameter with radius R=0.8 mm and into thread inner diameter with radius R=1.2 mm, respectively, with radius at profile top of 0.1 mm. Threaded part is separated from hemispherical head (having internal hexahedral hole for wrench) by screw neck 4.5 mm in diameter and 3.4 mm long. Screw design allows noninvasive introduction of screw into bored hole without special tap and compression between plate and bone, without use of drills of two diameters, and precise and stable fixation of bone fragments under conditions of regional osteoporosis. EFFECT: higher efficiency. 3 dwg