Apparatus and devices for percutaneously extending an existing spinal construct

Apparatus and devices for percutaneously extending an existing spinal construct ipsilaterally with an additional spinal construct in a patient are disclosed. The additional spinal construct comprises a rod connector that includes an elongate additional rod integrally attached thereto. The additional rod is placed through an access port in a first orientation generally parallel to the longitudinal axis of the access port and rotated to a different second orientation generally transverse to the longitudinal axis of the access port. During such rotation the additional rod is moved subcutaneously beneath the skin of the patient from the existing spinal rod to an additional bone engaging implant. In another arrangement, the extension of an existing spinal construct in a minimally invasive procedure comprises a rod connector having an offset support for receiving an additional spinal rod that may be placed laterally interiorly or exteriorly of the existing spinal construct.

BACKGROUND

The present disclosure contemplates devices and instrumentation for extending an existing spinal construct, and more particularly to procedures for achieving such extension minimally invasively, and preferably percutaneously.

An emerging trend in spinal fixation is an increased incidence of adjacent disc degeneration subsequent to a previous fixation or fusion. This subsequent degeneration often requires fixation or fusion of additional levels of the spine. It is common in current techniques to expose the entire prior construct to access all of the existing bone fasteners to permit removal of the connecting member spanning the fasteners. The connecting member is removed and replaced with a longer member, such as a rod, to engage an additional bone fastener added at the new levels to be instrumented.

This exposure of the prior fixation construct disrupts the existing construct complicating and lengthening the surgical procedure for adding the additional level of fixation. Such techniques are particularly problematic for a fixation construct spanning three or more vertebral levels. As such, there is a need for a device and method that facilitates the addition of further levels of fixation.

Several recent advancements have been disclosed that describe the extension of existing spinal constructs with minimal disruption to the existing construct. One example is shown in co-pending commonly assigned U.S. application Ser. No. 12/797,682, entitled “Devices and Methods for Adding an Additional Level of Fixation to an Existing Construct”, filed on Jun. 10, 2010 and published as No. 2010/0318131. Other examples include U.S. Pat. No. 7,976,567, entitled “Orthopedic Revision Connector”, issued on Jul. 12, 2011 to William B. Null, et al. and U.S. Pat. No. 8,021,399, entitled “Rod Extension for Extending Fusion Construct”, issued on Sep. 20, 2011 to Stephen Ritland. While these approaches represent improvements in revision techniques and devices, it would be advantageous to not only extend an existing construct in a relatively non-disruptive manner to such construct, but to do so in a minimally invasively and, preferably percutaneous procedure.

SUMMARY

It is an object of the present invention to provide apparatus and devices for adding an additional construct to an existing spinal construct in a patient preferably minimally invasively and more preferably, percutaneously.

DESCRIPTION OF THE EMBODIMENTS

Referring toFIGS. 1 and 2, an apparatus10is shown for extending an existing spinal construct12by adding an additional spinal construct14so as to increase the level of spinal fixation in a patient having previously undergone spinal fusion or other spinal surgery. The apparatus10generally comprises a rod connector extension assembly16, a spinal implant extension assembly18and an access port20. Rod connector extension assembly16includes a rod connector introducer21and a rod connector22comprising an elongate additional spinal rod24serving as a connecting element, as will be described. Spinal implant extension assembly18comprises an additional spinal implant26and an elongate extension28releasably coupled thereto. As illustrated, the existing spinal construct12as well as the additional spinal construct14are located ipsilaterly in the spine in this particular arrangement. As will be described in more detail below, rod connector introducer21comprises an elongate extension30releasably attached to the rod connector22. Each of extension28and access port20is sized and of length to be accessible outside the patient's skin. The patient's skin or fascia is depicted as a phantom line S for illustrative purposes only, with the understanding that the level of the fascia relative to the fixation location on the spine will vary from patient to patient. Spinal construct12is an existing spinal construct in the sense that it has been installed prior to the installation of the additional spinal construct14which means that existing spinal construct12may have been placed in a previous surgical procedure or may be placed during the same surgical procedure as, but prior to, additional spinal construct14.

Turning toFIG. 2, further details of the additional spinal construct14and the existing spinal construct12are described. The existing spinal construct12comprises at least two previously implanted bone engaging implants34and36each of which is engaged respectively to a corresponding vertebra38and40. Implants34and36are interconnected by an existing spinal rod42extending ipsilaterally therebetween. Existing spinal rod42includes an interconnecting portion42abetween implants34and36and an extending portion42bprojecting outwardly beyond implant34, although extending portion42bmay also project in the opposite direction beyond implant36. As shown, each of implants34,36is a polyaxial pedicle screw having a lower threaded fastener portion44,46for threaded engagement respectively in a pedicle of vertebra38and a pedicle of vertebra40. Each implant34,36includes a respective upper portion defining a yoke48,50each yoke having a respective threaded slot52,54for receipt of the existing spinal rod42therein. Set screws55and57respectively secure the existing spinal rod42to the implants34and36.

The additional spinal construct14comprises rod connector22including elongate additional spinal rod24, and a third bone engaging implant, namely additional spinal implant26. Spinal implant26, as depicted inFIG. 2, is a polyaxial pedicle screw having a lower threaded portion56and an upper yoke portion58that articulates relative to threaded portion56. The threaded portion56is threadedly engaged to a third spinal segment60as will be described. As depicted, spinal segment60is another vertebral body, it being understood that such spinal segment may be segment S1of the sacrum. The upper yoke portion58defines an open ended threaded slot62for receipt and support therein of the distal free end24aof additional spinal rod24and is fastened to the yoke portion58by a set screw64or other suitable fastener. While additional spinal implant26is described as being a pedicle screw, it should be appreciated that depending upon the application additional spinal implant26may include other bone engaging implants with fasteners such as hooks, or rod connectors.

Rod connector22comprises a lower first portion66and an upper second portion68articulatingly attached to the first portion66. The first portion66is attached to the existing spinal rod42as will be further described. The second portion68includes a connecting portion70projecting therefrom that in the arrangement described defines the elongate additional rod24terminating in distal free end24a. As illustrated inFIGS. 2 and 3the additional spinal construct14is considered to be inline with the existing spinal construct12. In such an arrangement, the upper second portion68of the rod connector22is positioned above and substantially in alignment with the axis of the existing spinal rod42. The connecting portion70has a first extent71and a second offset extent defined by additional rod24with a jog72therebetween. Extent71is positioned above bone engaging implant34while the axis of additional spinal rod24is aligned generally parallel to and colinear with the axis of the existing spinal rod42. As such, the existing spinal rod42and the additional spinal rod24are spaced approximately the same distance from a mid-line plane through the spine of a patient. It should be appreciated that depending upon the anatomy of the patient the orientation of the additional rod24relative to the existing rod42may differ.

Turning now toFIGS. 4-8, further the details of the rod connector22are described. The lower end of the first portion66of rod connector22comprises a pair of spaced hooks74and76each of which includes a respective projecting rod engagement member74aand76a. Hooks74and76are spaced from each other at a distance defining an opening78that allows the existing rod42to be received therebetween.

The first portion66of the rod connector22is attached to the second portion68by ball insert80which allows the first portion66to rotate and articulate relative to the second portion68, as will be described. The ball insert80comprises a truncated sphere having a first outer spherical surface82and a second outer cylindrical surface84, as shown inFIG. 5. The outer spherical surface82has a maximum diameter greater than the maximum diameter of the second outer cylindrical surface84. The second portion68has an interior spherical surface86as shown inFIGS. 6 and 7defining a socket for receipt of the spherical surface82of the ball insert80. Interior spherical surface of socket86has a diameter slightly greater than the maximum diameter of first outer spherical surface82of the ball insert80. The socket86has an entrance opening88that has a diameter less than the diameter of interior spherical surface of socket86and slightly greater than the maximum diameter of outer cylindrical surface84of the ball insert80. The ball insert80is inserted through socket opening88along an axis of the ball insert80defined by a longitudinal axis of the outer cylindrical surface84. As such, the ball insert80will pass through the socket opening88and into socket86. Once therein, ball insert80is rotated 90° such that the outer spherical surface82is in sliding facing relationship with the interior spherical surface of socket86. In this position, exterior threads90on an upper portion of the first portion66are threadably engaged into interior threads92of the ball insert80. The ball insert80may be secured to the threads90of the first portion66to prevent loosening by locking pins94which may be installed through clearance openings95on opposite sides of first portion68. The structure and operation of the ball insert80relative to socket86are fully described in commonly assigned U.S. application Ser. No. 11/560,587, entitled “Multi-axial Spinal Fixation System”, filed on Nov. 16, 2006 and issued as U.S. Pat. No. 8,162,990, the disclosure of which is incorporated herein by reference in its entirety.

As described and as shown inFIGS. 6 and 7, the ball insert80and the joined rod connector first portion66can jointly articulate relative to the second portion68about axis96defined by the centerline of opening97having interior threads98extending into the second portion68in communication with spherical socket86. In addition, first portion66can rotate relative to second portion68about an axis of engagement100defined by the centerline of exterior threads90of the first portion66. InFIG. 6the axis of engagement100and axis96of the second portion68are linearly aligned, while inFIG. 7, for example, the axis of engagement100is disposed at an angle with respect to axis96with first portion66having been articulated relative to second portion68. In the position shown inFIG. 7, the first portion66is in an unlocked position and may still rotate about axis of engagement100so as to cause hooks74and76to engage existing rod42, allowing greater flexibility for the attachment of the rod connector22to the existing rod42.

Referring toFIGS. 5 and 6a device for rotating the first portion66relative to the second portion68as well as for providing a provisional retention of the rod connector22to an existing rod42is described. A rotation element102supported by the first portion66comprises a rotation pin104, a wave spring106and a retention ring108. The rotation pin104comprises a head104ahaving an internal hex socket104bfor receipt of the hook rotator, as will be described. Socket104bmay comprise other suitable socket configurations, such as a conventional Torx configuration. Rotation pin104further comprises a shank104chaving an upper outer hex surface104da distal outer cylindrical surface104eand a larger intermediate cylindrical surface104fbetween surfaces104dand104e. Surfaces104d,104eand104fmay also include other suitable configurations.

To assemble the rotation element102to the rod connector22, the rotation pin104is inserted into opening97along axis96through threads98and into opening110interiorly of threads90of first portion66. The interior surface112of opening110comprises a complementary hex configuration for matable receipt of the hex surface104dof rotation pin104. With such hex surfaces in engagement, rotation of the rotation pin104will cause rotation of the first portion66. Wave spring106is placed over intermediate cylindrical surface104fand retention ring108is placed over distal cylindrical surface104e. Retention ring108is secured to distal cylindrical surface104eby laser welding or other conventional joining techniques. Securement of the retention ring108to the rotation pin104compresses the wave spring106between the retention ring108and an inner surface114adjacent, and substantially orthogonal, to interior surface112of opening110in the first portion66. As such, rotation element102is movably supported on said first portion66by wave spring106with the distal end of the retention ring108defining a rod engagement surface108anormally biased into the opening78between the hooks74and76of the first portion66. Such biased interference of the rod engagement surface108ainto opening78allows the existing rod42to be received into opening78and provisionally held by the rod engagement members74aand76aupon rotation of the hooks74and76under the bias of wave spring106as shown inFIG. 8. It should be appreciated that other spring elements, such as a helical spring, may be used as alternatives to wave spring106.

While the rod connector22is provisionally retained to the existing rod42by the rod engagement members74aand76aunder the bias of wave spring106, this position is an unlocked position with rotation element102serving as a provisional holding element. A device for locking the rod connector22in a locked position relative to the existing rod42is described with further reference toFIGS. 5 and 6. A locking element such as a set screw116has exterior threads116afor threadable rotational engagement with interior threads98extending within the second portion68. The upper proximal end of the set screw116comprises a suitable socket, such as a Torx hexalobe socket116bfor receipt of a suitable tool for inserting and rotating set screw116. The lower distal surface116cis configured to engage the upper surface of head104aof rotation pin104during rotational insertion. Continued insertion and tightening of the set screw116into threads98will cause the rod engagement surface108aat the lower end of the rotation element102to forcibly engage the existing rod42, effectively relieving the bias of wave spring106to thereby lock the first portion66to the existing rod42. The force against the existing rod42also causes the first portion66and thereby the ball insert80to move downwardly relative to second portion68forcing the outer spherical surface82at the lower half of ball insert80tightly against interior spherical surface of socket86of second portion68, thereby locking first portion66and second portion68securely together.

Referring still toFIGS. 4 through 7further details of the rod connector22are described. Projecting outwardly from second portion68is a connecting element70. In this arrangement, connecting element70includes first extent71and elongated additional rod24terminating in distal end24a. Connecting element70includes a jog72between first extent71and additional rod24causing the additional rod24to be offset relative to the first extent71so as to accommodate spinal anatomy. It should be appreciated that the height of jog72may be varied to provide different offset dimensions between additional rod24and first extent71. In some arrangements, jog72may be eliminated such that first extent71is colinear with additional rod24. In addition, first extent71and/or additional rod24may be curved so as to accommodate different spinal anatomical conditions. In the arrangement shown, additional spinal rod24defines a longitudinal axis24bthat extends transverse to axis96of the second portion68of rod connector22. In one application, for example, axis24bmay be disposed at an angle of approximately 90° with respect to axis96, shown inFIGS. 5 and 6. In the arrangement shown, rod connector22is formed as a one-piece structure. Connecting element70including elongated additional rod24may be otherwise integrally attached to second portion68by any suitable fastening means, including without limitation, welding, brazing and screws.

Turning now toFIGS. 9-12, details of the free hand rod connector introducer21are described. Rod connector introducer21comprises an elongate hollow extension30and a handle118interconnected to extension by an offset bracket120. Handle118may be selectively moved to different angular orientations by releasing and interlocking projection122into multiple grooves120a,120band120cin bracket120. Three positions are shown, namely 0°, 45° and 90° with handle118being in the 0° position shown inFIG. 9and in the 45° position as shown inFIG. 12. Other angular orientations may also be provided. Hollow extension30comprises an elongate outer sleeve124having a proximal end124aand a distal end124bwith a lumen124cextending fully longitudinally therethrough. Proximal end124ais suitably attached to bracket120and distal end124bis configured to secure releasably to the second portion68of the rod connector22.

As illustrated in further detail inFIG. 10, the rod connector securement structure at the distal end124bof sleeve124comprises a projecting attachment pin126and a skirt member128disposed diametrically opposite pin126. Attachment pin126is of generally oval shaped configuration and comprises a flexible latch126aprojecting from a side surface of pin126. Skirt member128projects axially downwardly from distal end124band has a concave inner surface configured to correspond to the outer curved surface68aat one end of second portion68. Attachment pin126is configured to be received in a complementary oval shaped hole130formed in an upper surface of second portion68of rod connector22(seeFIGS. 7-8) with flexible latch126abeing releasably attached to a ledge130aformed in a side wall of hole130in a snap-fit manner as shown inFIG. 10a. With attachment pin126received in hole130and skirt member128extending in close proximity around a portion of curved surface68a, the outer sleeve124is substantially prevented from rotating relative to both the second portion68of rod connector22and elongate additional rod24which is integral with second portion68. While attachment pin126and skirt member128are effective in releasably securing the outer sleeve124to the rod connector second portion68, it should be appreciated that other releasable securement structure, such as screw threads, may be used.

Referring now toFIG. 11, rod connector introducer21is shown preliminarily attached to rod connector22. To provide a more secure attachment, an inner elongate hollow sleeve134is included. Inner sleeve134has a proximal end134aand a distal end with a lumen134cextending fully longitudinally therethrough. Proximal end134aterminates in a flange134dhaving a hex surface for engagement with a wrench or other suitable tool. Distal end134bcomprises external threads134efor threadable attachment with the interior threads98in the second portion68of rod connector22. After outer sleeve124is preliminarily attached to rod connector22, inner sleeve134is inserted through lumen124cof sleeve124with threads134eof the inner sleeve threadably engaging threads98in the second portion68of rod connector22. Continued tightening of inner sleeve134causes flange134dto engage an upper surface of distal end124aof outer sleeve124thereby compressing the outer sleeve124between flange134dand rod connector22for secure attachment thereto.

With extension30suitably releasably secured to rod connector22, a hook rotator136is inserted into the lumen134cin the inner sleeve134, as shown inFIG. 12to complete the rod connector extension assembly16. Hook rotator136comprises an elongate shaft136ahaving a proximal end136band a distal end136c. Proximal end136bincludes a tool attachment surface136dhaving a hex or other suitable configuration for engagement with a hand wrench135(seeFIG. 21). Distal end136ccomprises an engagement surface136ehaving a complementary mating configuration, such as hex configuration, for engagement with the socket104bof rotation pin104. As described above with reference toFIG. 5rotation of the rotation pin104causes rotation of rod connector first portion66and hooks74and76projecting therefrom.

Hook rotator136includes at its proximal end a connection portion136fand a ring136g. Ring136gis pinned to connection portion136fto prevent relative rotation therebetween but is spring biased to allow axial translation when ring136gis depressed distally. Ring136gincludes an internal hex surface that engages the hex surface of the tool attachment surface136dwhen ring136gis biased normally upwardly, thus preventing rotation. When ring136gis depressed distally downwardly by a suitable tool such as by hand wrench135, the internal hex surface of ring136gdisengages from the external hex surface of tool attachment surface136d, thereby allowing rotation of the shaft136arelative to connection portion136f. Such disengagement allows the tool attachment surface136dto engage a complementary hex surface (not shown) within the hand wrench135such that rotation of the hand wrench135rotates the elongate shaft136a. Upon rotation of the shaft136aby hand wrench135from outside the patient, the first portion66of the rod connector22and thereby hooks74and76are also rotated in a manner to effect connection of the rod connector22to existing rod42, as will be described.

As hook rotator136is inserted into the lumen134cof inner sleeve134engagement surface136eis properly seated within the socket104bof rotation pin104. If proper seating is not achieved a marker or other suitable indicator may extend from the proximal end of elongate shaft136ato inform the surgeon that engagement surface136eis not properly inserted into socket104b. The first portion66with hooks74and76may be rotated manually until proper seating is achieved. Upon such proper seating, connection portion136fof hook rotator136is releasably attached to the bracket120at bracket portion120dby a flexible portion136h, as shown inFIG. 12to hold connection portion136ffixed relative to extension30. As such, rotation of elongate shaft136arelative to connection portion136falso rotates shaft136arelative to extension30and the rod connector22attached thereto. With the rod connector extension assembly16thus being assembled, longitudinal axis24bof the elongate additional rod24projects outwardly from extension30and transverse to axis96of the second connector portion68. In the arrangement shown, the angle between longitudinal axis24band axis96is substantially 90°. While a 90° angle is suitable, it should be appreciated that other angles may be contemplated.

In a preferred arrangement of rod connector extension assembly16, hook rotator136is formed at its distal tip136ias illustrated inFIG. 12ato have a curved configuration defining a ball hex shape. Thus, while the complementary mating configuration of engagement surface136eis constructed to engage socket104band substantially prevents rotation unless shaft136ais rotated, the ball hex shape will allow some articulation of the rod connector first portion66relative to second portion68, as illustrated inFIG. 7, even when engagement surface136eis seated within the socket104bof rotation pin104. With the rod connector first portion66being disposed at an angle with respect to rod connector second portion68, first portion66may still be rotated about axis of engagement100by hook rotator136. It should be understood that the distal tip136iof rotator hook136may also be formed to be relatively flat such that when the complementary mating configuration of engagement surface136eengages socket104bthere will be substantially no articulation of the first portion66, with such first portion66being held generally fixed relative to the rod connector introducer21by the hook rotator136.

Turning now toFIGS. 13-14, details of the access port20are described. Access port20comprises an elongate sleeve20ahaving a proximal end20band a distal end20cfor placement into the patient adjacent the existing spinal construct12. The access port20is of length such that the proximal end20bprojects out from the patient's skin S when the distal end20cis positioned adjacent existing construct12. Sleeve20aincludes a perimetric sidewall20dand a lumen20eextending lengthwise therethrough. Lumen20eis sized to receive the rod connector introducer21with the rod connector22secured thereto for attachment of the rod connector22to the existing spinal rod42. Sleeve20ahas a slot20fextending axially for a length through the sidewall20dsuch that the slot20fextends outside the patient when the distal end of the access port20is positioned adjacent existing construct12. In the arrangement shown, slot20fis arranged to face the additional spinal implant26to be implanted and extends axially fully through both the proximal end20band the distal end20c. Slot20fis sized and configured to receive therethrough the rod connector introducer21and the connecting portion70of rod connector22with the elongate additional rod24projecting therefrom. Slot20gis formed diametrically opposite slot20f, as shown inFIG. 14, slot20gextending through distal end20cand extending axially through perimetric sidewall20dfor a length that extends outside skin S of the patient. Slot20gis sized and configured to receive therethrough at least a portion of the rod connector22and rod connector introducer21to accommodate rotation of the rod connector introducer21, as will be described. A bracket138may be utilized to fix the access port20to an operating table in a conventional manner so as to maintain the access port20in place throughout the surgical procedure. While access port20is described in this arrangement as being generally tubular, it should be appreciated that access port may include other suitable structures such as by a pair of opposed blades defining a lumen therebetween, wherein the blades may be coupled at their proximal ends by a suitable ring or other coupling member.

Having described the devices and instruments for extending an existing spinal rod construct in a patient, the procedures for such extension are now described with particular reference toFIGS. 15-23. The first procedure relates to percutaneously extending an existing spinal construct12as shown inFIG. 15with an inline ipsilateral additional construct14as described above. The engagement of the additional spinal implant26as a component of the additional spinal rod construct14is described. Spinal implant extension assembly18comprises an elongate extension28which includes a hollow sleeve140releasably secured to the additional spinal implant26. Spinal implant26is described as noted above with reference toFIG. 2as being a polyaxial pedicle screw in this arrangement. Sleeve140has a pair of opposing slots142extending axially through the sleeve diametrically apart. The slots142are aligned and in communication with the slot62in the upper yoke portion58(seeFIG. 2) of the spinal implant26. The additional spinal implant26is percutaneously attached to the pedicle of the third spinal segment60, which may be a segment of the sacrum51or another vertebral body. Additional spinal implant26is introduced through a small percutaneous incision144made through the skin S of the patient. The incision144is approximately 10-30 mm in length. The dilation of incision144and the percutaneous attachment of spinal implant26to a spinal segment such as vertebral body60is fully described in commonly assigned U.S. patent application Ser. No. 12/818,965, entitled “System for Percutaneously Fixing a Connecting Rod to a Spine”, filed on Jun. 18, 2010, and issued as U.S. Pat. No. 8,142,437, (the '437 patent), the disclosure of which is incorporated herein by reference in its entirety. Once spinal implant26is attached to the vertebral body60, the sleeve140as well as slots142project out from the patient through dilated incision144with the slots142being rotatably manipulable upon rotation of sleeve140to be aligned with slot20fof access port20as will be described with reference toFIG. 16.

Using fluoroscopy or other suitable imaging techniques, the existing spinal rod42is initially targeted so as to establish the position of the existing rod42in the patient. In this instance, the interconnecting portion42aof existing rod42is targeted rather than extending portion42bprojecting outwardly beyond implant34. A small percutaneous incision146is made through the skin S of the patient, the incision146being approximately 10-30 mm in length, although other suitable dimensions may be used. A targeting rod148is placed through the incised puncture and pushed through the tissue of the patient down to the existing spinal rod42. Once the access path has been created and the position of the existing rod42established a series of sequentially increasing dilating instruments are inserted over the targeting rod148. As depicted inFIG. 16, the dilating instruments include dilating cannulas150,152and154of increasing diameter. The number of dilating cannulas may vary depending upon the procedure and the desired extent the incision146is to be expanded upon dilation. In addition, the dilating cannulas may include features that maintain the lateral position of such cannulas relative to existing rod42during insertion. Access port20is then finally placed over the last dilating cannula154with the opposing slots20fand20gcommunicating with existing rod42such that the distal end20cof access port20straddles but does not attach to existing rod42, as shown inFIG. 16. The dilating instruments are then removed as illustrated inFIG. 17leaving the access port20in place. The central longitudinal axis of the access port20is generally aligned with and perpendicular to the longitudinal axis of existing rod40. Bracket138may be utilized to fix the access port20to the operating table so as to maintain access port20fixed in place throughout the surgical procedure. The proximal end20bof the access port20as well as slot20fproject out from the patient's skin, S, with access port slot20fbeing generally aligned with and in facing relation to slots142of sleeve140in spinal implant extension assembly18. Although also shown as extending outwardly of the patient's skin, S, slot20gmay be of length to lie below the patient's skin, S.

By reference toFIG. 18as well as toFIG. 1, the introduction of the rod connector22through manipulation of the rod connector extension assembly16is explained. The handle118may be in the 45° position for this stage of the procedure. With access port20fixed in place a surgeon grasps handle118and initially orients the extension30of rod connector introducer21generally parallel to the spine of the patient such that the axis24belongate additional rod24is oriented in a first position generally parallel to the longitudinal axis of access port20. In this position, the additional rod24is within the lumen20eof access port20with the connecting portion70of rod connector22extending through and projecting outwardly from slot20fof access port20. Through manipulation of rod connector introducer21the additional rod24is moved in this first orientation until the rod connector22is below the skin S of the patient. At this point, the rod connector introducer21, with the access port slot20fserving as a guide, is rotated so that additional rod24is rotated clockwise as viewed inFIG. 19in a direction indicated by arrow, R. from its first orientation out from access slot20fand toward sleeve140of spinal implant extension assembly18. During such movement, the distal end24aof additional rod24is subcutaneously moved through tissue of the patient beneath the skin S of the patient toward the sleeve140of spinal implant extension assembly18.

Continued rotation of handle118in the direction R further rotates rod connector introducer21until the distal end24aof additional rod24approximates sleeve140. With fluoroscopy the distal end24aof additional rod24is guided into slot142that is in facing relationship with access port slot20f, as shown inFIG. 20for ultimate reduction into slot62of additional spinal implant26. It should be appreciated that the additional rod distal end24amay be directly received within slot62of additional spinal implant26. During this portion of the rotation of rod connector introducer21, the rod connector22as well as the distal end124bof the rod connector introducer extension30may project outwardly from the opposite access port slot20gto accommodate the rotation of rod connector introducer21.

Upon final rotation of rod connector introducer21by handle118as shown inFIG. 21the distal end24aof additional rod24extends through both slots142of sleeve140and is either situated in slot62of additional spinal implant26(FIG. 2) or closely thereto. In this position the additional rod24has been moved to a second different orientation such that the axis24bis transverse, and substantially perpendicular, to the longitudinal axis of access port20. Also with the aid of fluoroscopy, the rod connector22at this point receives the existing spinal rod42within the opening78between hooks74and76of rod connector first portion66. As described above, with first portion66capable of articulating while being held against rotation by the hook rotator136, proper receipt of existing spinal rod42within opening78is achieved even if the longitudinal axis of rod connector introducer21is not precisely perpendicular to the axis of existing rod42thus allowing for potential irregularities of the spine. In this position, existing spinal rod42is in an unlocked position with respect to rod connector22. Prior to rotation of rod connector hooks74and76to engage existing rod42for locking, the surgeon may, if necessary, reduce the additional rod24into slot62of additional spinal implant26. Such reduction may be achieved by connecting a rod persuader (not shown) to a rod persuader coupling member156disposed at the proximal and of sleeve140. The rod persuader including its structure and cooperation with rod persuader coupling member156is fully described in the '437 patent, the disclosure of which is incorporated herein by reference in its entirety.

With continued reference toFIG. 21as well as toFIGS. 5-6, the engagement of the rod connector22to the existing spinal rod42is described. Hand wrench135is used to suitably depress ring136gfor attachment to tool attachment surface136das described above and is rotated either by hand or an appropriate tool. Rotation of wrench135rotates hook rotator shaft136aas well as engagement surface136ewhich is engaged within socket104bof rotation pin104. Upon such rotation of the shaft136a, the rotation pin104rotates the first portion66of the rod connector22about the axis of engagement100in a manner to facilitate alignment of opening78relative to existing rod42. Hooks74and76and the respective rod engagement member74aand76aare then rotated in a manner to engage the existing rod42. As the hooks74and76are rotated, the engagement surface108aat the distal end of rotation element102engages the existing rod42under the bias of wave spring106pushing the head104aof the rotation pin104slightly upwardly into opening97of first portion66. During such rotation the existing rod42is thereby received between the rod engagement member74aand76aand rotation pin engagement surface108ain a snap-fitting movement that provides a tactile and potentially an audio indication to the surgeon that the existing rod42is properly seated in the rod connector22in a provisional engagement whereby the rod connector22is held on but not locked to the existing rod42. Rod connector first portion66is rotated approximately 60° with respect to second portion68to establish such provisional engagement. It should be understood that first portion66may be rotated relative to second portion68at other angles which may be less than 60° or up to approximately 90°.

Once the rod connector22has been rotated to the provisional engagement position, the distal end24aof additional rod24may then be secured to additional spinal implant26as described with reference toFIG. 22. Set screw64is suitably attached to a driver instrument158and sized and configured to introduce the set screw64with instrument158attached thereto into and through hollow sleeve140until set screw64engages the threads in the slot62of the upper yoke portion58. Set screw64is tightened by rotation of instrument158to secure the additional rod24to the additional spinal implant26. Instrument158is then detached from set screw64and removed from sleeve140.

Turning now toFIG. 23as well as toFIGS. 5-6and11, locking of the rod connector22to additional rod42is described. After removing hook rotator136and inner sleeve134from rod connector introducer21, set screw116is suitably attached to a driver tool160with the distal tip of tool160in engagement with socket116bof set screw116. Tool160with set screw116attached thereto is sized and configured to be received within lumen124cof outer sleeve124of rod connector introducer21until set screw116engages the threads98in rod connector second portion68. As noted above, the lower distal surface116cof set screw116engages the upper surface of head104aof rotation pin104during rotational insertion of set screw116. Continued insertion and tightening of the set screw116into threads98will push the rotation pin104downwardly causing the rod engagement surface108aat the lower end of the rotation element102to forcibly engage the existing rod42. The force against the existing rod42also causes the first portion66and thereby the ball insert80to move downwardly relative to second portion68forcing the outer spherical surface82of ball insert80tightly against interior spherical surface of socket86of second portion68, thereby locking first portion66and second portion68securely together.

With rod connector22properly secured to existing spinal rod42, tool160is detached from set screw116and removed from rod connector introducer21. Spinal implant extension assembly18, rod connector introducer21and access port20are also then removed from the patient. To facilitate removal of rod connector introducer21from rod connector22, handle118may be adjustably moved to a position generally parallel to the longitudinal axis of outer sleeve124as shown, for example inFIG. 9. With the removal of the instruments the inline ipsilateral extension of the existing spinal construct12by additional spinal construct14as shown inFIG. 2is complete and the incisions144and146maybe appropriately sutured. In the percutaneous procedure described, the rod connector22is inserted through the access port20and rotated for attachment to the existing rod42in a top loading procedure without disturbing the existing implants34and36or the previous connections to the existing rod42. Such top loading allows a surgeon to insert the rod connector22by manipulating the rod connector by rotation and connect it to the existing rod42from above the spine facilitating the percutaneous procedure.

In the procedure just described, rod connector22is attached to existing spinal rod42by targeting the interconnecting extent42abetween two existing bone engaging implants34and36, each of which is engaged respectively to a corresponding vertebra38and40. The elongate additional rod24projecting from rod connector22may be attached to additional spinal implant26in either the caudal or cephalad direction. Using the same technique described herein, it should be understood that rod connector22may also be used to attach an existing spinal construct to other bony segments, not only within the spine, such as vertebral bodies or the sacrum, but outside the spine, such as the ilium. Such an arrangement is contemplated, for example as shown inFIG. 24where bone engaging implant36is attached to vertebral body L5and bone engaging implant34is attached to segment S1of the sacrum and these implants are interconnected by existing spinal rod42with extending portion42bprojecting in the caudal direction. With extending portion42bhaving sufficient extent, extending portion42bmay be targeted for receipt of and connection to rod connector22, as described above. A third bone engaging implant162such as an iliac screw similar to spinal implant26may be percutaneously secured to the ilium through a separate spaced incision with a releasable bone implant extension assembly similar to spinal implant extension assembly18, as described in the '437 patent. Rod connector22may then be inserted with additional rod24passed subcutaneously from existing rod42to the iliac screw162in a manner as described hereinabove to form the additional construct extending from segment S1of the sacrum to the ilium. Rod connector22may be configured with or without jog72and curved if desired to accommodate the anatomical conditions.

Having described a particular arrangement of rod connector22wherein additional rod24is integrally attached thereto, two alternative arrangements are described wherein a rod connector is configured to receive an additional rod rather than such additional rod being integrally attached. The first alternative arrangement is shown and described with reference toFIGS. 25 and 26. Rod connector200comprises a first portion66articulatingly attached to a second portion68, first portion66and second portion68having structure identical to first and second portions66and68respectively of rod connector22. Rod connector200further includes a connecting portion202projecting outwardly from second portion68and terminating in an additional rod support204. Support204comprises a yoke206having a pair of opposing upstanding arms206aand206bdefining an open ended slot208having internal threads210. The slot208is sized and configured to receive and support therein an additional spinal rod212which is fastened to the yoke206by a set screw214or other suitable fastener. As shown inFIG. 26, rod connector200is configured to be attached to the existing spinal rod, such as rod42and to receive and support additional rod212in an orientation that may be generally parallel to existing rod42. As such, the axis of additional rod212is laterally offset with respect to the axis of existing rod42. It should be appreciated that depending upon the anatomy of the patient the orientation of the additional rod212relative to the existing rod42may not necessarily be parallel.

By reference toFIGS. 27 and 28a minimally invasive technique for attaching rod connector200to a spinal rod in an existing spinal construct is described. A rod connector introducer21as described above may be releasably attached to second portion68of rod connector200. An elongate extension28as described above with respect to spinal implant extension assembly18includes a hollow sleeve140that is releasably secured to the additional rod support204in the same manner as attached to additional spinal implant26. To attach rod connector200to existing spinal rod such as rod42, either the interconnecting portion42abetween two existing bone implants or the extending portion42bprojecting beyond one of the two existing bone implants may be targeted for attachment.FIG. 28illustrates the targeting of the interconnecting portion42afor connection. Using fluoroscopy or other suitable imaging techniques as described above, a small incision216is initially formed through the skin S. The incision216is enlarged radially and laterally with a series of sequentially increasing dilating instruments with the ultimate insertion of an oval access port218. Oval access port218is sized and configured to receive the assembly220comprising rod connector200, rod connector introducer21and the elongate extension28. A hook rotator, such as hook rotator136, may be inserted through rod connector introducer21to engage the rotation element104in rod connector200so as to restrain the hooks74and76from rotation, as set forth above. The assembly220is introduced into oval access port216with the rod connector200in an orientation that is maintained beneath the skin until the interconnecting portion42aof existing spinal rod42is received within the opening78between hooks74and76, as described above. Rotation of the hooks74and76about axis of engagement100and connection of the rod connector200to the interconnecting portion42aof existing rod42proceeds thereafter as described above.

In the attachment of rod connector200by the procedure shown inFIG. 28, the yoke206and therefore the additional rod212are located laterally farther away from the midline of the patient than the existing spinal rod42. In a variation, the rod connector200may be attached with the yoke206located interiorly of the existing spinal construct12such that the additional rod212lies closer to the midline of the patient. Once the rod connector200is properly secured to the existing rod42, the rod connector introducer21with the hook rotator136and access port218are removed and the elongate extension28is maintained. A third bone engaging implant such as an iliac screw similar to spinal implant162inFIG. 24may be percutaneously secured to the ilium through a separate spaced incision with a releasable bone implant extension assembly similar to spinal implant extension assembly18, as described in the '437 patent. An additional rod may now be used to percutaneously interconnect yoke206of rod connector200with the third bone engaging implant by passing the additional rod subcutaneously beneath the skin of the patient using the extensions attached to yoke206and the third bone implant as guides in a manner as fully described in the '437 patent. It should be appreciated that an additional rod may also be percutaneously placed between the yoke206of rod connector200and other bony segments within the spine, such as vertebral bodies or the sacrum, either in a caudal or cephalad direction.

Turning now toFIGS. 29 and 30the second alternative arrangement is shown and described. Rod connector300comprises a first portion66articulatingly attached to a second portion68, first portion66and second portion68having structure identical to first and second portions66and68respectively of rod connector22. Rod connector300further includes a connecting portion302projecting outwardly from second portion68and terminating in an additional rod support304. Support304comprises a yoke306having a pair of opposing upstanding arms306aand306bdefining an open ended slot308having internal threads310. The slot308is sized and configured to receive and support therein an additional spinal rod312which is fastened to the yoke306by a set screw314or other suitable fastener. As shown inFIG. 30, rod connector300is configured to be attached to the existing spinal rod, such as rod42and to receive and support additional rod312in an orientation generally inline with existing rod42. As such, the axis of additional rod312is generally parallel to and colinear with the axis of existing rod42. Such an arrangement is contemplated where an existing spinal construct exists, for example, between bone implants attached to vertebral bodies L4and L5and extension is desired generally inline to sacral segment, S1in the caudad direction or to vertebral body L3in the opposite cephalad direction. In either case, the extending portion42bof the existing rod42is targeted for connection by the rod connector300. It should be appreciated that depending upon the anatomy of the patient the orientation of the additional rod312relative to the existing rod42may not necessarily be precisely inline and colinear.

To attach rod connector300to existing spinal rod such as rod42that interconnects two existing bone engaging implants, the extending portion42bprojecting beyond one of the two existing bone implants is targeted. The attachment of rod connector300through an oval access port such as access port218within dilated incision similar to incision216, proceeds in a similar manner as described with respect to rod connector200. A third bone engaging implant such as a pedicle screw similar to spinal implant26, may be percutaneously secured to the sacrum or additional vertebral body through a separate spaced incision approximately 10-30 mm in length with a releasable bone implant extension assembly similar to spinal implant extension assembly18, as described in the '437 patent. An additional rod may now be used to percutaneously interconnect yoke306of rod connector300with the third bone engaging implant by passing the additional rod subcutaneously beneath the skin of the patient using the extensions attached to yoke306and the third bone implant as guides in a manner as fully described in the '437 patent.

While the existing spinal construct12has been described herein as being extended by a single level, it should be appreciated that the extension may comprise two or more levels with the devices and instruments as described herein. In addition, while the devices and instruments described herein provide surgeons the ability to extend existing spinal constructs at least minimally invasively and more preferably, percutaneously, it should be understood that a surgeon may also use the described devices and instruments in an open procedure if that is the surgeon's surgical preference.