Surgery – Instruments – Orthopedic instrumentation
Patent
1996-12-17
1998-04-07
Tucker, Guy V.
Surgery
Instruments
Orthopedic instrumentation
606 69, 606 73, A61B 1780
Patent
active
057358532
DESCRIPTION:
BRIEF SUMMARY
This application is filed under 35 USC 371 based on PCT/SE95/00744 which was filed on Jun. 16, 1995 published as WO95/35067 Dec. 28, 1995.
TECHNICAL FIELD
This invention relates to implant devices of the type comprising a plate element with a number of bone screw holes and at least two bone screws which are insertable and lockable in bone screw holes, the head portion of each bone screw being adapted to be inserted in an annular hole insert mounted in the associated hole, said hole insert having a convex, preferably at least essentially part-spherical, outer annular surface, which is adapted to cooperate with a matching concave, preferably at least essentially part-spherical hole wall surface, such that a bone screw inserted in a bone screw hole can be made to occupy different angular positions in relation to the plate element by rotating or tilting the hole insert and the bone screw therein in relation to the hole wall.
BACKGROUND ART
Implant devices of the above type are often used in orthopaedic operations, for instance with a view to stabilising fractured bones, stabilising the positions of vertebrae and reducing vertebrae.
Various solutions for imparting flexibility to the bone screws as regards their directions in relation to the plate element have been suggested. For instance, it has been suggested that the head portion of the bone screws employed should have a part-spherical outer surface adapted to cooperate with a matching hole surface in a plate element, such that the bone screw may occupy the desired angular position in relation to the plate element when screwed into the hole, this angular position being fixed when the bone screw is locked in relation to the plate element, e.g. with the aid of an inner expansion locking screw. Prior to locking, the bone screw is maintained against the plate element as a result of the application pressure obtained when the plate element is pressed against the subjacent bone.
In one variant of this type of construction, the spherical mounting enabling an alteration of the relative angular positions of the bone screw and the plate element is achieved with the aid of a special hole insert, which has a part-spherical circumferential surface and is positioned in a matching hole in the plate element and which is formed with a central through hole adapted to receive a bone screw. This latter hole thus corresponds to an ordinary bone screw hole in a plate element.
It has, however, been found desirable that the plate element should not have to be applied against the subjacent bone, pressing against it. Thus, it has also been suggested that a part-spherical head portion of a bone screw be accommodated and in itself retained in a matching hole in a plate element. However, this construction is complicated in many respects and is even practically inapplicable in certain cases, for instance when several bone screws are to be arranged in different angular positions in relation to the plate element.
OBJECTS OF THE INVENTION
One object of this invention is to provide an implant device enabling the bone screws to be applied in simpler and more expedient fashion.
Another object of the invention is to provide an implant device enabling enhanced flexibility as regards the positions of the bone screws in relation to the plate element.
Yet another object of the invention is to provide an implant device opening up new and more extensive fields of application.
SUMMARY OF THE INVENTION
According to the invention, these objects are achieved by an implant device which is of the type mentioned by way of introduction and has the distinctive features recited in the appended claims.
In a first aspect of the invention, the implant device is distinguished by the fact that the head portion of a bone screw is adapted, when in unlocked state, i.e. when not locked in relation to the plate element by means of e.g. a locking screw, to be retainable in an associated hole insert, so as to be nondisplaceable in the longitudinal direction but preferably be rotatable. In a preferred embodiment,
REFERENCES:
patent: 4388921 (1983-06-01), Sutter et al.
patent: 4484570 (1984-11-01), Sutter et al.
patent: 5057111 (1991-10-01), Park
patent: 5151103 (1992-09-01), Tepic et al.
patent: 5269784 (1993-12-01), Mast
patent: 5501684 (1996-03-01), Schlapfer et al.
patent: 5520690 (1996-05-01), Errico et al.
LandOfFree
Bone screw for osteosynthesis does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bone screw for osteosynthesis, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bone screw for osteosynthesis will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-8583