Patent Description:
<CIT> discloses an orthopedic implant kit comprising several items, in particular a pedicle screw fixed to a mounting tube made of two half-shells which can be easily disassembled.

Pedicle screws of the prior art can be divided in two main groups:.

When implanting a pedicle screw into a bone several steps are needed. For almost each of those steps a dedicated instrument is used.

<CIT> discloses a surgical instrument set for the implantation of a spinal column stabilization system. The instrument set has two bone screws comprising a connecting element receiver, and a connecting element inserted and fixed with the receiver. A multi-function sleeve includes proximal and distal ends and defines a longitudinal axis, where the sleeve comprises a connecting element-coupling device, a spreading device-coupling device and a holding instrument-coupling device. An internal wall surface of the sleeve is rotationally symmetrical with respect to the axis where no projections protrude from or beyond the internal wall surface in a direction of the axis.

<CIT> discloses an instrument set for minimally invasive preparation of a bone nailing procedure. The set has a base casing with a selective axial length including a drive end and a tool grip end. The casing has an inner diameter selected for retaining a work casing or a nail. A dilation casing has an external diameter that is adapted to the inner diameter of the base casing. The dilation casing has an end section with an outlet opening for guiding longitudinal adjustment of a fixed guide wire.

The work casing has an inner diameter adapted for guiding a drill or cutter and/or a nail and an inset at its one end for gripping the tool grip end.

<CIT> discloses an invention which includes surgical retractors that comprise an expandable frame that includes at least two base components, a connector, and at least two retractor blades attached to the expandable frame. Also included are surgical retractors that comprise a housing component that includes a cylindrical portion and a contiguous blade portion, assemblies comprising a surgical retractor assembled to at least one obturator, illuminated surgical cannulas, and methods of using the same during a surgical procedure.

<CIT> discloses a spinal stabilization system which includes an implant and instrumentation for stabilizing the spine. In one embodiment, the system includes a plate having a side rail and a channel extending adjacent the side rail. A pedicle screw assembly is positioned in the channel in releasable engagement with the side rail. The pedicle screw assembly includes a polyaxial screw seated in a lower housing having a lower locking flange. An upper housing having an upper locking flange secures the plate to the lower housing. The side rail of the plate is releasably engaged between the upper locking flange and the lower locking flange. The upper and lower housings include on-board locking mechanisms for fixing components in the screw assembly. The screw assembly and plate are inserted and oriented by remote manipulation. Minimally invasive techniques for inserting the implant are performed with the instrumentation, and cause minimal disturbance to surrounding tissue.

An objective of the present invention is to reduce the number of items which are required for manipulating and fixing an orthopedic implant (pedicle screw, nut, rod, etc..

Another objective is to reduce the number of instruments for manipulating those items.

Another objective is to facilitate the handling of the instruments.

Those objectives are met with the orthopedic system according to claim <NUM>.

In a first embodiment an orthopedic implant kit comprises a lockable poly-axial screw, a tissue dilatation sleeve, a screw driver, a screw extender, a rod, rod-reduction means, a set screw driver, a torque limiting mechanism and a screw releasing instrument.

The lockable poly-axial orthopedic screw comprises a head and a threaded portion which form two separate elements, fixed to each other but each element may be independently oriented along a specific direction. The threaded portion may, for instance, rotates around the screw head and may adopt several possible orientations. More precisely, the threaded portion may be oriented anywhere within a conical volume, the top of the cone corresponding to the contact point between the head and the threaded portion.

The screw furthermore comprises a locking element which, when activated, suppresses the relative movement between the threaded portion and the head. This configuration is named "mono-axial" because the threaded portion may be oriented along a single (fixed) axis with respect to the head.

According one embodiment the locking element is a clip having a U-shape. In this case the head and the threaded portion contains cavities which are adapted to receive the branches of the U-shape clip.

Preferably, in the mono-axial mode the head may still freely rotate around its own axis, with respect to the threaded portion. Such a mechanism may be obtained with a U-shape clip and with an annular groove located around the upper part of the threaded portion. In this case the branches of the clip are sliding within the annular groove.

In another embodiment the screw head contains at least one longitudinal relief, such as a groove or a ridge, which is dimensioned in a way as to receive a corresponding relief, such as a ridge or a groove, which is located within the distal end of a screw extender.

In another embodiment the screw comprises a concave seat located in the proximal end of the threaded portion and a corresponding convex shape located at the distal part of the screw head. This configuration reduces the screw length and increases the strength and the rigidity of the system.

The screw extender comprises a hollow cylindrical body made of two half tubes separated by two opposite longitudinal slots having an open end towards the cylindrical body distal part, this later one being dimensioned to receive and hold a screw head. The cylindrical body furthermore comprises an internal threaded part.

According to one embodiment the cylindrical body is made of a single piece and the distal part is radially expandable by its own elasticity, in such a way as to allow an easy clipping and subsequent releasing of a screw head.

To facilitate its radial expansion, the screw extender may include expanding means, for instance an internal rotatable tube which, when rotated pushes away the two half tubes from each other.

In a preferred embodiment the internal part of the cylindrical body distal end contains at least one relief, such as a ridge or a groove, which is dimensioned to be received within the longitudinal relief of a screw head which includes a corresponding relief, as mentioned previously. With this configuration it hinders the distal part of the half tubes to separate from each other by its own elasticity thus making a very strong attachment between the screw extender and the screw head. An additional benefit is that the relative rotation between the screw head and the cylindrical body is avoided.

In a preferred embodiment a rod reduction instrument is located within the cylindrical body. Advantageously the rod reduction instrument is essentially made of a shaft with a threaded distal part which is the counterpart of the cylindrical body internal threaded part. So when it is rotated within the cylindrical body the shaft may move along the cylindrical body main axis.

In another embodiment a set screw driver is (also or alternatively) located within said cylindrical body. In this case also, the set screw driver may also essentially be made of a shaft with a threaded distal part.

Advantageously the set screw driver comprises a torque limiting mechanism.

In one embodiment this mechanism includes a breakable pin and a thread free rotatable shaft. The pin is laterally crossing the rotatable shaft and its ends are fixed within the threaded rotatable shaft. The threaded and the threaded free shafts are rotatably linked to each other but when a certain torque is reached the pin breaks and each shaft may freely rotates with respect to the other shaft.

In another embodiment a screw releasing instrument is (also or alternatively) located within said cylindrical body.

Advantageously the screw releasing instrument is essentially made of a shaft with a threaded distal part.

In a particularly interesting embodiment, the same shaft with a threaded distal part is used for the rod reduction instrument (and potential sponylolisthesis), the set screw driver and the screw releasing mechanism.

The tissue dilatation sleeve according to the invention comprises a flexible conical part which is adapted to be temporarily fixed to the distal part of a screw extender as defined.

In one embodiment the conical part is made of several longitudinal flexible blades having each a substantially triangular shape.

The invention will be better understood in the following part of this document, with non-limiting examples illustrated by the following figures:.

The examples below more precisely relate to a thoracolumbar fusion system consisting of pedicle screws and rods combined with single use instruments. A typical pedicle screw system consists of the screw implants and the instruments for placing the screws.

<FIG> shows an example of an implant kit.

This kit contains a tissue dilatation sleeve <NUM>, a handle <NUM>, a rod <NUM>, a rod inserting instrument <NUM>, a shaft <NUM> which can be used as a rod reduction instrument and/or a set screw driver and/or a screw releasing instrument, a pedicle screw <NUM>, a screw extender <NUM> and a screw driver <NUM>.

The lockable poly-axial screw <NUM> illustrated in particular in <FIG> includes a head <NUM> and a threaded portion <NUM>. <FIG> also shows a set screw <NUM> which may be fixed to the head after the insertion of a rod <NUM>. The screw <NUM> furthermore comprises a locking element <NUM> having a U-shape. When the locking element <NUM> is fully inserted in the screw head <NUM> the orientation of threaded portion <NUM> is blocked with respect to the head <NUM>. Inversely, when the locking element is retrieved, the threaded portion <NUM> can be freely oriented with respect to the screw head <NUM>.

The lockable poly-axial screw may therefore be transformed into a mono-axial screw, thus allowing having mono-axial and poly-axial capability in the same product. A blocking system defined previously allows the surgeon to choose if he/she wants to use the screw in mono-axial or poly-axial mode. As mentioned mono-axial capability is achieved by pushing the locking element (clip) <NUM> and poly-axial capability is achieved by removing the clip <NUM>. The clip <NUM> is just an example of a blocking system; other technical solutions can also be imagined such as a pin.

Any orientation of the axis can be considered when the mono-axial is used, i.e. the screw axis and the screw head may be oriented along different directions.

<FIG> represent the attachment of a pedicle screw <NUM> to the distal end <NUM> of a screw extender <NUM>, by inserting the screw head <NUM> within the distal end <NUM>. In this operation the head <NUM> is guided with a plurality of ridges <NUM> located within the distal end <NUM> and grooves located on the head <NUM>. With such a system the screw head is better retained within the screw extender <NUM>.

Any suitable material can be used for the screw extender <NUM>(plastic, polymer, metal, etc..

<FIG> represent the positioning of the rod <NUM> in the screw head <NUM>, a rod reduction and the tightening of the set screw <NUM> in the screw head <NUM>.

The multi-use instrument <NUM> (see also <FIG>) is defined by an upper part <NUM> and a lower (threaded) part <NUM>.

The rod <NUM> may be pushed downwards by rotating the multi-use instrument <NUM> within the cylindrical body <NUM>.

After the rod insertion within the head <NUM>, the set screw <NUM> is fixed to the head <NUM> by further rotating the multi-use instrument <NUM>.

The multi-use instrument <NUM> is also provided with a torque limiting mechanism (see <FIG>). When the set screw <NUM> is fixed within the head <NUM> and the multi-use instrument <NUM> further rotated, the torque increases, up to a point where the pin <NUM> breaks. A further rotation of the multi-use instrument <NUM> has therefore no more effect on the set screw <NUM>. From that point the further rotation of the multi-use instrument <NUM> only induces a downwards pressure on the screw head <NUM>. The screw <NUM> is therefore progressively separated from the screw extender (see <FIG>).

This screw releasing mechanism from an instrument offers the possibility to release the screw <NUM> from the screw extender without laterally expanding the screw extender <NUM>.

It should be mentioned at this stage that this mechanism is not limited to the release of pedicle screws. Any other item may be used.

To summarize, the same instrument <NUM> can be used for rod reduction, for fixing a set screw to a screw head and for releasing a screw from a screw extender.

It should be underlined that the instrument is not limited to this triple use of the same instrument. A double use is also comprised, for instance rod-reduction and fixation of the screw set to the screw head.

<FIG> and <FIG> show an alternative solution to attach a pedicle screw to an screw extender, by rotating an inside tube (not illustrated) the half-tubes <NUM> are expanded by their own elasticity. This allows a screw to be inserted and fixed to it by for example clamping the outer surface around the screw. The same principle can be used as an alternative to detach the screw extender from a screw.

The clamping system also achieves part of its rigidity, by resting on support surfaces on the screw head.

<FIG> shows a concave screw top <NUM>, inside a convex upper half ball <NUM>, allowing the rod <NUM> and the set screw <NUM> to be set lower in the screw head <NUM>, thus decreasing the total build height, and increasing the strength and rigidity of the system.

<FIG> represents a tissue dilatation sleeve <NUM> containing four triangular flexible blades <NUM> intervened into each other and forming a cone <NUM>. The cone <NUM> is mounted at the tip of a screw extender <NUM>, with a tear off spiral. This allows the tissue to be pushed aside as the screw extender <NUM> is inserted into a body. Once in place, the surgeon may remove the sleeve <NUM> while the screw extender remains in the body. Any suitable number of blades can be used for forming the cone.

<FIG> show a procedure using the items which have been previously presented.

In a first step (<FIG>) two puncturing guide wires <NUM> are positioned in the spine.

A first screw extender <NUM> with a screw <NUM> attached and surrounded by a dilatation sleeve is then inserted through the tissue (<FIG>), and along the guide wire <NUM>. The screw extender <NUM> is rotated and/or pushed.

A similar operation is carried out with a second screw extender <NUM> and screw <NUM> (<FIG>).

A screw driver <NUM> is inserted within the screw extender <NUM>. Its distal end is introduced within the upper part of the screw threaded portion <NUM>. The screws <NUM> are then rotated and enter the vertebrae (<FIG>).

The tissue dilatation sleeves <NUM> are removed (<FIG>).

A rod inserting instrument <NUM> with a rod <NUM> at its end is transversally crossing the tissue (<FIG>).

The rod <NUM> is positioned above the screw head <NUM> (<FIG>) and the multi-use instrument <NUM> is introduced within the screw extender <NUM>, to such an extent that the set screw <NUM> is positioned above the rod <NUM>, in line with the screw head <NUM> (<FIG>).

<FIG> to
<NUM> show the rod placement within the screw heads <NUM> and the fixation of the set screw <NUM> within the screw head <NUM>.

<FIG> illustrate the screw release from the screw extender <NUM> and the screw <NUM>, the rod <NUM> and the screw set <NUM> in their definitive location.

The invention is of course not limited to those illustrated examples.

Claim 1:
An orthopedic system comprising:
- a screw extender (<NUM>) for holding a screw (<NUM>);
- a tissue dilatation sleeve (<NUM>) for removable attachment to the screw extender (<NUM>), the tissue dilatation sleeve (<NUM>) comprising:
a surrounding part for surrounding the screw extender (<NUM>),
a flexible conical part (<NUM>) extending from a first end of the surrounding part, the flexible conical part (<NUM>) tapering in direction away from the surrounding part, and
an annular part attached to a second end of the surrounding part,
characterized in that the annular part includes an annular orifice passing fully through the annular part to receive a finger of a user for pulling and removing the tissue dilatation sleeve (<NUM>) from the screw extender (<NUM>) along a longitudinal axis of the screw extender (<NUM>).