Patente US5720751 - Tools for use in seating spinal rods in open ended implants

TOOLS FOR USE IN SEATING SPINAL
RODS IN OPEN ENDED IMPLANTS

BACKGROUND OF THE INVENTION

The present invention relates to tools for use in surgically 5 installing apparatus for correcting orthopedic deformities in a patient and, in particular, to tools specifically designed to facilitate alignment of or seating of spinal rods within open ended implants and which also facilitate closing off or capping the open ended implant while maintaining (he 10 proper orientation of the spinal rod with the open ended implant The tools of the present invention allow a surgeon to push or translate a rod toward and into an open end of one or more implants and/or to pull or translate one or a group of spinal bones toward the rod such that open ends of 15 implants in the bones receive the rod.

Spinal osteosynthesis apparatus generally comprises a rod or system of rods which are secured along at least a portion of the spine by bone screws, including sacral screws and pedicle screws, transverse connectors and bone hooks for stabilizing and adjusting spinal alignment. The bone screws, transverse connectors, bone hooks and related items which are intended for use in connecting the rods to the bone and to facilitate adjustment of the rods may collectively be 2J referred to as hardware or implants. In a very basic apparatus, the bone screws have a spinal rod receiving bore extending through a ring or head of the screw. The screws are secured in the vertebra at desired locations and a spinal rod is then extended through the spinal rod bore in each bone 30 screw. Set screws, inserted in threaded bores extending through the wall of the screw ring, preferably perpendicular to the axis of the spinal rod bore, are tightened to fix the translational and rotational relationship of the rods within the bores. The rods may then be bent or formed to support 3J the spine in a desired manner or to exert the desired corrective or stabilizing forces on the spine.

A slightly more complicated system uses transverse connectors in association with the bone screws to secure the spinal rods. The transverse connectors include an arm and a ^ head. The head has a spinal rod bore extending therethrough and the arm is normally equivalent in diameter to the spinal rod. The arm of the connector is inserted through the spinal rod bore in the pedicle screw then the spinal rod may be inserted through the spinal rod bore in the transverse con- 45 nectors. A threaded bore extends through the head of the connector perpendicular to the axis of the spinal rod bore. Once the rod is inserted through the bore in the transverse connectors, a set screw is inserted through the threaded bore in each connector and tightened to fix the relative position of 50 the rod within the spinal rod bore. Similarly a set screw is inserted in a threaded bore in the head of each pedicle screw and tightened to fix the position of the transverse connector with respect to the pedicle screws.

The pedicle screws, transverse connectors, bone hooks or 55 related implants or hardware may be of the closed end type as discussed above or of an open end type wherein the head of the screw or connector generally incorporates a U-shaped channel or groove, an upper end of which may be closed off by a cap or saddle to form the spinal rod bore. The threaded go set screw bore typically extends through the cap. With open end type implants, the spinal rod may be inserted from above, into the U-shaped channel instead of having to insert the spinal rod axially through the rod receiving bores of closed end type implants. 65

As noted previously, the spinal rods are generally bent or shaped to exert the desired corrective forces on the spine to

realign the spine. Therefore, to obtain the desired alignment the rod and the open ended implants often must be forced into alignment by generally driving the rod and the U-shaped channel of an open ended implant toward one another. Once the rod is seated in the open ended implant, the implant must be capped or closed off to secure the rod thereto.

Devices have been developed for driving spinal rods into alignment with implants, such as the Offset Mini-Corkscrew sold by Sofamor Danek used in combination with a Central Post Hook Holder or Hook/Screw Holder also sold by Sofamor Danek. This combination of tools is used to drive a spinal rod having connectors secured thereto into alignment with an open ended pedicle screw adapted to receive a portion of the connector such that the rod may be secured to the pedicle screw via the connector.

The Offset Mini-Corkscrew and Hook/Screw Holder are not adapted for use in seating a spinal rod within the U-shaped channel of an implant such as a pedicle screw. Use of the Offset Mini-Corkscrew and Hook/Screw Holder to do so would be impractical in that once the rod was seated within the U-shaped channel of an implant, the Offset Mini-Corkscrew would prevent installation of a cap to secure the rod therein. Further, manipulation of the Offset Mini-corkscrew relative to the Hook/Screw Holder is time consuming and somewhat inconvenient.

There is a need for a device for seating a spinal rod in a U-shaped channel of an open ended implant which permits capping of the implant while the rod is maintained in the seated alignment

SUMMARY OF THE INVENTION

The present invention comprises a set of tools for use in seating a spinal rod in a rod receiving channel in a head of an open ended spinal surgery implant such as a bone screw, hook or transverse connector. The set of tools according to the invention allows a surgeon to push or translate a rod toward and into the open heads of spinal implants and/or to pull or translate one or more bones with the implants thereon toward the rod so as to receive the rod in open heads of the implants. The tools are designed to permit installation of an implant cap on the head of an open ended spinal surgery implant while maintaining the spinal rod in a seated alignment therewith.

Each of the tools comprises an implant holder for grasping, holding or engaging an implant, and a pusher assembly including a pusher bar advanceable relative to the implant holder to drive, push or force a spinal rod into the rod receiving channel of an implant held by the implant holder or to draw the implant toward the rod such that the rod is received by the implant. The implant holders are of various configurations to facilitate holding or grasping of different types of implants or to accommodate different situations relating to the location of the implant. The pusher assembly is adapted for interchangeable use with each of the various implant holders.

Each of the implant holders includes a handle portion and an implant engaging portion. The implant engaging portion includes opposed engaging members for securing one of the implants therebetween. In one of the preferred embodiments, the implant holder is of unitary construction and the relative position of the engaging members is fixed. In other preferred embodiments, the implant holder is formed from two arms, each comprising a handle portion and an implant engaging portion or implant engaging member, secured together in a scissor like fashion such that

3 4

the implant engaging members may be advanced between and a pusher assembly to drive or force a spinal rod into the

open and closed positions relative to one another. rod receiving channel of an implant held by the implant

In one aspect of the present invention, the pusher bar holder; to provide such a set of tools in which the pusher

includes a pair of opposed legs defining a slot extending assembly is adapted for interchangeable use with different

therebetween. A lower cross member extends between the 5 implant holders; to provide such a set of tools in which the

opposed legs at lower ends thereof and an upper cross pusher assembly is securable to the implant holders; to

member extends between the opposed legs at upper ends provide such a set of tools which is adapted for use with

thereof. The lower cross member or abutment member is tools for use in installing caps having sets screws with break

adapted to engage a spinal rod and advance the spinal rod off heads secured thereto; and to provide such a set of tools

into a seated relationship with the rod receiving channel of "> which are relatively easy to use and particularly well

an implant. adapted for their intended usage.

The seating apparatus utilizing the pusher assembly with Other objects and advantages of this invention will

the slotted pusher bar is adapted for use in combination with become apparent from the following description taken in

a cap inserter having a handle, a stem and a head, the head conjunction with the accompanying drawings wherein are

of the cap inserter having a socket formed therein and 15 set forth, by way of illustration and example, certain

adapted for removably securing an implant cap to the head embodiments of this invention.

of the cap inserter. The slot in the pusher bar is sized to allow The drawings constitute a part of this specification and

insertion therethrough of a cap and at least a portion of the include exemplary embodiments of the present invention

cap inserter, to which the cap is removably secured. With the and illustrate various objects and features thereof. pusher bar pushing or holding a spinal rod in seated rela- 20

tionship in the rod receiving channel of an implant, a cap BRIEF DESCRIPTION OF THE DRAWINGS

nwy be installed on the implant via access through the slot FIG. lis a front plan view of a spinal rod pusher assembly

in the pusher bar. Qj a S^]U^ r(Kj seat£ng apparatus of the present invention.

In another aspect of the present invention the pusher 25 nG 2 fe an ^ d afld fr ^ view of me her

assemMy includes a threaded stem rotatably connected to assembly m snown ^ mG j witn broken t0

the pusher bar along the upper cross member. A receptacle sflow interior detail

having a threaded bore extending therethrough is fixedly __ _ . ... , , „ „ ,

secured to the handle portion of the implant holder. The TMJ 3 ls a cross-sectional view taken along line 3-3 of threaded stem is removably securable within the threaded J0

bore of the receptacle for use in mechanical advancement of FIG- 4 is a front plan view of an implant holder of the

the pusher bar toward and away from an implant held by the spinal rod seating apparatus of the present invention,

implant holder by rotation of the threaded stem. FIG. 5 is an enlarged bottom plan view of the implant

A pair of guides, which define a pair of pusher bar holder as shown in FIG. 4 taken generally along line 5—5

receiving channels may also be secured to the implant holder 35 of FIG. 4.

such that at least portions of the opposed legs of the pusher FIG. 6 is an enlarged and fragmentary rear plan view of

bar may be extended therethrough to guide advancement of the implant holder taken generally along line 6—6 of FIG.

the pusher bar relative to the implant holder. 5.

In another aspect of the invention the implant holder FIG. 7 is a front plan view of the spinal rod seating

includes a structural member or web having a lower edge 40 apparatus of the present invention showing the pusher

extending transverse to the axis of the rod receiving channel assembly secured to the implant holder.

of an implant secured between the implant engaging mem- FIG. 8 is an enlarged and fragmentary view of the spinal

bers. An opening extends between the lower edge of the web rod ... apparatus as shown in FIG. 7 and showing the

and the head of an implant secured between the implant spinal rod seating apparatus positioned to drive a spinal rod

engaging members. The lower edge of the web is adapted to 45 mto a seated alignment with an open ended bone screw.

function as a fulcrum for the stem of a cap inserter which „„ „ . . ., . „„ „ . ... . .

.. _, ,.. . . . . . . „ FIG. 9 shows a view similar to FIG. 8 in which a spinal

must be advanced through an arcuate motion to install a cap , . . .. . . . .. . ...

.B .. ... . . ... f rod has been driven into a seated alignment with an open

on an implant. The distance that the lower edge of the web . ,. , .,

j , , . ««. • 1 * ended bone screw by the spinal rod seating apparatus,

is spaced from an implant secured between the implant J r e rr

engaging members is preferably selected to facilitate instal- 50 mG- 10 18 a ... front Plan Vlew of a saddle <*P lation of a cap utilizing the cap inserter. lnserter for use m association with the spinal rod seating

apparatus and with portions broken away to show interior OBJECTS AND ADVANTAGES OF THE detail.

INVENTION FIG. 11 is an exploded and fragmentary perspective view

The objects and advantages of the invention include: to 55 showing a saddle cap inserter positioned for installing a provide a set of tools for use in seating a spinal rod in a rod saddle ^P wttl a set screw secured thereto, onto the head of receiving channel in a head of an open ended spinal surgery an °Pen ended 00116 screw with a sP^al rod extending implant such as a bone screw, hook or transverse connector therebetween.

by relative translation of the rod and implant toward one FIG. 12 is a fragmentary, right side elevational view of the another; to provide such a set of tools which facilitates the 60 spinal rod seating apparatus as shown in FIG. 9 with a spinal installation of a cap onto the open ended spinal surgery rod seated in me head of an open ended bone screw and with implant while maintaining the spinal rod seated relative portions broken away to show the positioning of a saddle cap thereto; to provide such a set of tools comprising multiple inserter relative to the seating apparatus for installing the cap tools each adapted for a different use; to provide such a set on the bone screw with a spinal rod extending therebetween, of tools with different tools for use with different implants; 65 FIG. 13 is a fragmentary rear plan view of the spinal rod to provide such a set of tools wherein each tool comprises an seating apparatus as shown in FIG. 12 in which the cap implant holder for grasping holding or engaging an implant, inserter has been used to install the cap.

« AnteriorContinuar »

Patentes

Tools for use in seating spinal rods in open ended implants