Bone screw with improved threads
Patent 5417533 Issued on May 23, 1995. Estimated Expiration Date: 
May 23, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
May 23, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesInventorAssigneeApplicationNo. 090550 filed on 07/13/1990US Classes:411/426, Tapered411/308, Involving dissimilarities in the sectional configuration of the threads411/411, Thread or shank structure606/73Threaded fastener elementExaminersPrimary: Wilson, Neill R.Attorney, Agent or FirmForeign Patent References
International ClassF16B 035/04AbstractA bone screw having a helical thread that gradually increases in thickness from the tip to the head of the screw. The thin thread at the tip of the screw can be inserted into a bone with minimal tearing or cracking of the bone. The thicker treads ascending from the tip to the head of the screw displaces bone against the superior (top) thread surfaces. This displacement of bone increases the screw's resistance to being pulled-out of the bone. The thicker core just below the screw head increases the screw's ability to withstand compressive and distractive loads. The core is thickest just below the head because it is at that point on the screw that the fulcrum loads are greatest.Other References
Field of SearchResilient elementHaving threads of different pitch, or a thread of varying pitch Involving dissimilarities in the sectional configuration of the threads Resulting in the deformation of one thread by the other By integral, interference-producing deviations from a standard thread shape Thread or shank structure Buttress thread Shank structure Tapered Pilot end having means enhancing fastening or installation Femoral screw Orthopedic fastener Threaded fastener element | |
