Surgery – Instruments – Orthopedic instrumentation
Patent
1999-07-16
2000-07-11
Buiz, Michael
Surgery
Instruments
Orthopedic instrumentation
606 73, A61B 1770
Patent
active
060865881
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to rachidian osteosynthesis surgery and more precisely to osteosynthesis systems for vertebral arthrodesis, that is to say systems which are intended to immobilize one of at least two adjacent vertebrae with respect to the other.
Among such systems, the invention concerns those which comprise at least one vertebral compression or distraction bar which extends along a part at least of the rachis, at least one and generally at least two vertebral anchoring members, for example a pedicellar screw or a hook, which is for example laminar, thoracic or pedicellar, and, associated with each anchoring member, a common support for receiving, coupling and immobilizing the bar and an end or head of the anchoring member.
In such systems arthrodesis is effected by virtue of locking together the vertebrae in question by the distraction or compression bar which is immobilized with respect to the anchoring members by way of the supports.
Among such systems, the invention concerns those which are of the type referred to as "polyaxial", in which, in opposite relationship to the rachis, the anchoring member has a free end head with a spherical surface in such a fashion that the support and the anchoring member can adopt a relative angular position which can be regulated and modified in all directions, according to the respective needs involved.
Polyaxial systems of that kind are described for example in European patent applications Nos 0 553 042 and 0 613 664. Those systems as illustrated by the two documents referred to hereinbefore by way of example all comprise a hollow support or socket whose open end has a recess or housing for receiving the head of the anchoring member, the cylindrical body of the socket having two longitudinal slots which open into the central bore for the distraction or compression bar to pass transversely with respect to the axis of the socket. To immobilized the assembly, a screwthreaded element is screwed onto the support and directly or indirectly acts on the bar axially with respect to the support, that is to say transversely with respect to the bar, to cause the latter to bear, also directly or indirectly, against the spherical head of the anchoring member, the head thus being pressed firmly against its seat which is disposed in the open end of the support.
Those known polyaxial systems suffer from a major disadvantage which is that the distraction or compression bar can be set in place or removed only by axial displacement with respect to the support, which requires inter alia preliminary removal and in general the absence of the screwthreaded immobilization element.
Another disadvantage of those systems is that it is possible to gain access to the head of the spherical member, in particular by means of a tool, only if the bar and the immobilization means are not there. That is highly inconvenient and troublesome as on the one hand, when setting the anchoring member in place on a vertebra by screwing or hooking, the presence of the bar would be useful in particular for giving the practitioner an indication of the orientation to be imparted to the anchoring member, and on the other hand, once the bar is in place, it is impossible for the practitioner to take action on the anchoring member for adjusting the final position of the arrangement by virtue of the fact that the head of the anchoring member is covered by the bar and, yet again, bearing in mind that the anchoring member has to be fitted into the support prior to its being set in place on the rachis, the support is in no way retained in relation to the anchoring member and therefore has a tendency to float or fall along the shank of the anchoring member, with the result that the operations for setting the anchoring member in position are highly inconvenient and awkward from the point of view of the practitioner.
SUMMARY OF THE INVENTION
The aim of the present invention is in particular to remedy those disadvantages and consequently to provide a system of the foregoing type in which access o
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patent: 5735851 (1998-04-01), Errico et al.
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patent: 5743907 (1998-04-01), Asher et al.
patent: 5776135 (1998-07-01), Errico et al.
patent: 5810819 (1998-09-01), Errico et al.
Ameil Marc
Huppert Jean
Jermann Jean-Louis
Marnay Thierry
Aesculap AG & Co. KG
Buiz Michael
Reip David O.
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