Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2005-03-01
2005-03-01
Robert, Eduardo C. (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
C081S044000, C279S042000
Reexamination Certificate
active
06860889
ABSTRACT:
A tool for gripping and removing mechanical fasteners such as pedicle screws. With reference to FIG.7, the device generally resembles a screwdriver, having a handle on one end, a long shaft in the middle, and fastener engaging means on the other end. The fastener engaging means comprises a set of two or more jaws having inward facing gripping surfaces positioned to grasp the external surfaces of a screw head. The jaws are formed as part of a collet slidably mounted within an outer thread sleeve. The thread sleeve is attached to the shaft. A tapered journal on the collet interacts with a tapered bore in the thread sleeve so that when the collet is pulled into the thread sleeve, the set of two or more jaws are squeezed together. The threaded engagements between the collet and the thread sleeve should be the reverse of the thread on the screw to be removed; i.e., if a right-hand screw is to be removed then the threaded engagement between the collet and the thread sleeve should be made with a left-hand thread. In operation, the jaws are placed over the screw head and the device is rotated in a counterclockwise direction (for removal of a screw with a right-hand thread). The inward facing surfaces on the jaws bear against the bolt head, thereby impeding the rotation of the collet relative to the thread sleeve. The left-hand threaded engagement between the collet and the thread sleeve therefore pulls the collet further into the thread sleeve, whereupon the tapered bore squeezes the jaws more tightly together. Thus, the reader will appreciate, applying torque to the device when it is in position on a screw head simultaneously torques the screw head and squeezes the jaws more tightly together. The inward facing surfaces are also provided with an undercut in order to accommodate axial misalignment between the jaws and the screw head.
REFERENCES:
patent: 1116532 (1914-11-01), Armstrong
patent: 2634641 (1953-04-01), Hodges
patent: 2669896 (1954-02-01), Clough
patent: 2753746 (1956-07-01), Cummings
patent: 3373639 (1968-03-01), Van Dalen
patent: 3377893 (1968-04-01), Shorb
patent: 3529497 (1970-09-01), Brooks
patent: 3735650 (1973-05-01), Weng, Jr.
patent: 4204308 (1980-05-01), Marling
patent: 4393872 (1983-07-01), Reznik et al.
patent: 4877020 (1989-10-01), Vich
patent: 5095779 (1992-03-01), Batten
patent: 5213015 (1993-05-01), Disston, Jr.
patent: 5604487 (1997-02-01), Frymier
patent: 5649931 (1997-07-01), Bryant et al.
patent: 5664467 (1997-09-01), Breeze
patent: 5667513 (1997-09-01), Torrie et al.
patent: 5755732 (1998-05-01), Green et al.
patent: 5890271 (1999-04-01), Bromley et al.
patent: 5957467 (1999-09-01), Hornung
patent: 6183472 (2001-02-01), Lutz
patent: 6189422 (2001-02-01), Stihl
Bonati Alfred O.
Ware Philip J.
Comstock David
Horton John Wiley
Robert Eduardo C.
LandOfFree
Clamping screw extractor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Clamping screw extractor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Clamping screw extractor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3368760