Surgery – Instruments – Orthopedic instrumentation
Patent
1995-10-19
1998-04-21
Buiz, Michael
Surgery
Instruments
Orthopedic instrumentation
606 60, 606 64, 606 72, 606 73, A61B 1770
Patent
active
057412545
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the field of implants for ostheosynthesis, in particular for the spine, and more particularly it relates to an implant for an ostheosynthesis device, in particular for the spine, of the type comprising an anchoring portion for anchoring to bone and a body in which a channel is formed suitable for receiving a rod, the channel opening out sideways in the body, a hollow element suitable for surrounding the body and possessing two notches suitable for receiving the rod on either side of the body, and means for fixing the hollow element on the body.
Document EP-A-0 517 059 teaches an implant of that type.
Nevertheless, that known implant suffers from a certain number of drawbacks. Firstly, it is relatively bulky because the body of the implant possesses a threaded extension extending backwardly, with the fixing means consisting in a nut of relatively large dimensions screwed onto the extension. In addition, by its very nature, the nut has projecting angles which are generally undesirable for implants since they damage the environment.
Also, nut tightening generally needs to be performed with an extremely large amount of torque, and as a result during tightening there is a risk of metal particles being torn off and released from the threads of the nut and/or the threaded extension, thus running the risk of metallosis developing in the patient.
The present invention seeks to mitigate or at least to attenuate all those drawbacks of the prior art.
To this end, it proposes an implant of the type mentioned in the introduction and characterized in that: having a rounded top portion in which an opening is formed; top portion of the cover and a threaded portion that is screwed in the tapped hole.
Advantageously, going from the outside towards the center of the body, the channel slopes towards the bone anchoring portion.
In a preferred embodiment, the body has a top portion that is substantially hemispherical in shape and the cover has a top portion that is of complementary substantially hemispherical shape; then preferably, the head of the screw has an outside surface that extends the rounded top surface of the cover with continuity.
In the same spirit, the invention also provides an implant for an ostheosynthesis device, in particular for the spine, of the type comprising an anchoring portion for anchoring to bone and a body in which a channel is formed suitable for receiving a rod, the channel opening out sideways in the body, a hollow element fixed on the body to hold the rod in the channel, and means for fixing the hollow element on the body, the implant being characterized in that: towards the bone anchoring portion; and terminated by a generally flat edge bearing against the rod at either end of the channel to lock said rod in the channel, an opening being formed in said top portion; top portion of the hollow element and a threaded portion that is screwed in the tapped hole.
Advantageously, the body has a top portion that is substantially hemispherical in shape and the hollow element comprises a cap that is of complementary substantially hemispherical shape.
Then preferably, the head of the screw has an outside surface that extends the rounded top surface of the cap with continuity.
Finally, it is appropriate for the screw to be mounted in unloseable manner in the opening of the hollow element.
Other aspects, objects, and advantages of the present invention appear more clearly on reading the following detailed description of preferred embodiments thereof given by way of example and made with reference to the accompanying drawing, in which:
FIG. 1 is an exploded perspective view of an implant of the invention and an associated rod;
FIG. 2 is a perspective view of the implant and the rod in the assembled state;
FIG. 3 is an elevation view from the side of a portion of the implant; and
FIG. 4 is an elevation view from the side of an implant constituting a variant embodiment of the invention.
With reference to the drawing, there can be seen an implant for ostheosynthesis of the spine w
REFERENCES:
patent: 5190543 (1993-03-01), Schlapfer
patent: 5380325 (1995-01-01), Lahille et al.
Henry Patrick
Lapresle Philippe
Missenard Gilles
Buiz Michael
Shai Daphna
Stryker Corporation
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