FR2714590A1 - Transverse fixing member for spinal column supporting rods - Google Patents

Abstract

The transverse fixing for rods used in spinal surgery, comprises a forged steel member (1) with hook-shaped ends to go under the rods (3), containing an inner spring-loaded element (2) with sharpened ends (4) to grip the rods, which are of a softer material. The spring-loaded element is fitted into the transverse fixing under tension with the aid of a compression tool, and the fixing is shaped so that the tension in the spring-loaded element is directed towards the rods.

Description

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  The present invention relates to a device for connecting together the rods in spine operations; this device is called "transverse fixator During operations on the spine the surgeon after having implanted pedicle screws in the vertebrae comes to place in the l" U "formed by the heads, preformed rods; these rods after connections with the screws (this connection ensuring the distance between the vertebrae is maintained); the two rods must be secured

  between them by mechanical devices.

  lo The techniques currently used generally consist of 3 elements; 2 hooks whose size allows to hold the rod and a flat element that the surgeon will form into a policeman's hat to avoid the backbone; the profile formed by the hook and the rod being held by a screw; this screw has a

  primer of rupture which makes it possible to break the 6 sides of the screw head.

  The screw exerts its pressure by stamping on the flat part, the assembly comprising neither a braking system nor

game catching up.

  The disadvantages of these types of transverse fixators

are many.

  The shaping and setting up of the flat part is tedious, the spinal operation being long the setting up of these transverse fixators must be quick and precise, moreover its design must include the minimum of parts to avoid assemblies.

delicate.

  The present invention relates to two types of transverse fasteners, their use may be mixed depending on the location and the

expected number.

  A model of transverse fixator will have a locking system by spring claw; the second of a system of

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  screw locking; in both cases the shape of the fixative will be

  provided curved to allow the passage of the backbone.

  The distance between the two rod supports will be fixed for each fixator, which will require for a total operation a certain number of these devices in order to satisfy the different centers; the distance between the two rods being variable. The transverse fastener equipped with a spring claw will preferably be composed of two parts; 1 piece of forged stainless steel (FIG 1 rep 1) whose shade and treatment 10 will ensure medical compatibility and a claw made of spring steel (FIG I rep 2) whose ends will be machined in

  bevel shape (FIG 1 rep 4) so that the very small support section can under the pressure generated by the spring stress (FIG 1 rep 2) penetrate the rod and thus form a very high resistance to sliding .

  The forged steel part (FIG 1 rep 1) receiving the spring claw will be designed so that it can receive inside its

  forms the spring claw; this shape will be designed to hold the claw in position in its middle (FIG 2 rep 6) and to also maintain the claw near these ends (FIG 1 rep 4).

  These shapes located near the ends (FIG 1 rep 5) will maintain the claw on the forged part before the middle of the latter is forced to enter its housing. In addition the forged part (FIG 1 rep 1) will provide sufficient clearance for the claw to absorb the deformations of the latter depending on the mechanical tolerances and the diameters of the rods; in fact, it will have been clearly expressed that the pointed ends of the claw are inserted into the rods when the operator using high pressure (depending on the shape of the claw, its length and its section) will constrain the claw inside the forged part in its groove (FIG 2 rep 6);

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  the developed length of the claw spring being slightly more

  important that the developed length of the forged part to the length of the neutral fiber of the claw, the excess of length being taken up by the deformation of the claw which to maintain its spring effect must be able to have a housing in the part forged corresponding to its new trajectory.

  Once locked, the assembly is stable, the sliding of the fixator is limited by the claw whose knives are anchored in the rods, the possible movements of the claw relative to the forged piece being taken up respectively by the two abutments located near the knives (FIG 1 rep 5) of the claw and through the central groove

  holding in the forged part (FIG 2 rep 6).

  The advantages of the product object of the present invention described are numerous, the preformed parts with different dimensions i5 are ready for use, their fixing (locking) is instantaneous (this locking is carried out using an effect clamp multiplied); the system once locked is underserable and with automatic backlash adjustment, moreover a hole (FIG 2 rep 7) will be provided in the upper central part of the forged part (FIG 1 rep 7); this hole will allow the introduction of an axis and the thrust exerted on the latter will dislodge the claw from its throat which will allow disassembly

  extremely easy and quick of the entire fixator.

  The second model of transverse fixator will vary only in its principle of fixing, it will also consist of a forged element whose envelope shape will not vary (FIG 3 rep 1) it will include the two "U" capable of receiving the rods but these the latter will be held in place by screws (FIG 3 rep 2); these screws will be located at

inside the forged part.

  The position of the screws will be such that the axis of the screws must pass above the center of the rod so as to guarantee that the latter

  are pressed against the bottom of the "U" of the forged part.

  The forged part will be hollowed out in its center to allow the mounting of cI hexagon socket screws. lc passagc des clés (FIG 3 replO)

necessary for tightening.

  The "U" of the forged piece will include in their centers a growth in the form of a coil of material (FIG 3 rcp,) and (FIG 5 rep 9) so that the pressure of the screw causes this protrusion to penetrate into the rod (FIG 3 rcp 3) ct (1; 1 (4 rcp 3) and thus ensure a much greater resistance to

translation forces.

  The screws in treated acicr (FIG 3 rop 2) (toughness more important than the acicr scrvant to constitute the rods (FIG 3 rep 3) will have their ends in the form of cuvettes or in pointed ends (FIG 3 i) cp 8) ( at the practitioner's choice); the forged accr part will have a smooth zone at the entry of the tapping to facilitate placement

is screw (] FIG 6 ,.

  in the two cases of the transverse fasteners described above, particular care taken with the surface condition; all sharp edges will be removed (radiated angles and polished surface finish) from

  so as to offer the minimum of aggression.

Claims (4)

  1) Device called transverse fixator for ensuring the connection between the rods used in spine operations characterized in that it comprises a shaped piece of forged steel (1) and a locking means making it possible to immobilize the tigcs (3) 2) Device according to claim 1 characterized in that the locking means is constituted by a spring claw (2) equipped at these ends with two pointed parts (4) intended to penetrate the rods realiscated in materials of lower hardness , the spring claw will be placed in compression in the forgecó piece (1) by the intermedium of a force-reduction pliers, the forged part (1) comprising a machining (6) in which will be accommodated the spring under stress; the forces transmitted by the claw will be applied to the two rods housed in the "U" of the forged part 3) Device according to claim 1 or the revcndicatiuon 2 characterized in oc that the "UV of the forged part (1) may include small bosses (9) so that the rods made of softer materials can under the forces of compression of the claw penetrate inside the rods (3).   4) Device according to any one of the claims   previous characterized in that the forged part (1) has dcs   bosses (5) which hold the claw (2).