Access instruments to extend a surgical working channel

A channel retractor with one or more gate tracks to receive one or more slide gates to hold one or more extended retractors away from the surgical access channel running through the extended retractor. The distal ends of the one or more extended retractors held by the one or more slide gates holding tissue distal to the end of the channel retractor to maintain an extended access channel beyond the distal end of the channel retractor. The channel retractor assembly may be used to hold open an extended access channel through the psoas muscle to allow access to the spine or through other tissue in other surgical access techniques.

BACKGROUND

Field of the Disclosure

This disclosure relates generally to minimally invasive surgical techniques including techniques and implants for provision of therapy to a spine from a lateral approach. Implants that may be used with other approaches to the spine are disclosed. Minimally invasive surgical techniques using one or more extended retractors to create an extended access route such as the non-limiting example of lateral access to the spine are disclosed.

This application builds upon the concepts expressed in U.S. Pat. No. 8,795,167 B2 issued Aug. 5, 2014 for Spinal Therapy Lateral Approach Access Instruments. The contents of the '167 are incorporated by reference herein.

General Comments and Terminology

In the context of the present disclosure, as used herein the term “assembly” refers to implants, instruments and instruments systems which are configured to comprise multiple components, which may or may not be contiguous. It is further understood that individual components may themselves be configured as sub-assemblies, e.g., comprising a plurality of component materials, and that the formation of the components may involve intermediate processes or appliances.

It will also be understood that upon formation of assemblies from multiple components and deployment, individual components of the present disclosure may or may not remain as discernibly distinct. It will also be understood that, for convenience, system components may be packaged and provided either individually, or as in “kits,” and either as reusable or disposable.

As used herein, the term “biocompatible” refers to an absence of chronic inflammation response or cytotoxicity when or if physiological tissues are in contact with, or exposed to (e.g., wear debris) the materials and devices of the present disclosure. In addition to biocompatibility, in another aspect of the present disclosure it is preferred that the materials comprising the instrument systems are sterilizable.

In one aspect of the present disclosure, certain components of the device assemblies and systems of the present disclosure are configured to comprise biocompatible materials and are able to withstand, without wear, multiple cycles/procedures without failing. It will be further understood that the length and dimensions of instruments and components described herein will depend in part on the target site selection of the treatment procedure and the physical characteristics of the patient, as well as the construction materials and intended functionality, as will be apparent to those of skill in the art

In order to make it easier for a reader to find certain sections of this document that are of particular interest to the reader, a series of headings have been used. These headings are solely for the purpose of helping readers navigate the document and do not serve to limit the relevance of any particular section to exclusively the topic listed in the heading.

In the context of this discussion: anterior refers to in front of the spinal column; (ventral) and posterior refers to behind the column (dorsal); cephalad refers to the direction or location that is closer to the patient's head (sometimes “superior”); caudal (sometimes “inferior”) refers to the direction or location that is closer to the feet. Proximal is closer to the beginning of the channel and thus the surgeon; distal is further from the beginning of the channel and in use more distant from the surgeon. When referencing tools including cutters or other tools distal would be the end intended for insertion into the access channel and proximal refers to the other end, generally the end closer to the handle for the tool.

The sequence of operations (or steps) is not limited to the order presented in the claims or figures unless specifically indicated otherwise.

Prior Art

Earlier work by one of the co-inventors of the current application discloses a minimally invasive surgical technique that may be used to traverse the psoas muscle to form an access channel to the lateral side of lumbar disc spaces. This earlier work resulted in U.S. Pat. No. 8,795,167 for Spinal Therapy Lateral Approach Access Instruments. The '167 patent is hereby incorporated by reference in its entirety.

The '167 showed a number of access tools and implants. The implants are not relevant to the present disclosure and will not be further discussed. In order to understand the advantages of the present disclosure, it is useful to review the first embodiment of an access system disclosed in the '167.

FIG. 1shows an example of a channel retractor164. Note that the channel retractor164may have a substantially uniform cross section (as taken with respect to the longitudinal axis). The cross section of the channel retractor164may be round (uniform radius), elliptical, square, oblong, or other shapes. In many instances the cross section will have rounded surfaces even for shapes such as a square or rectangle that is longer than it is wide. The cross section of the channel retractor164inFIG. 1may be described as a rounded rectangle as it has a pair of curved ends separated by straight walls. The channel retractor164is sometimes called a tubular retractor as it comprises a lumen that is an opening at a proximal end212extending throughout its length to an opening at a distal end216, the channel retractor164thus having an inner perimeter206. The channel retractor164may have a stabilizer arm168for use to connect to a table mounted retractor arm.

Creating an Opening in the Psoas Muscle.

To prepare for work on the psoas muscle, it may be useful to add lighting. One way to add lighting is to plug one end of a fiber optic cable into a light source in accordance with manufacturer's instructions. The other end of the fiber optic cable may be attached to a stadium mount light. The stadium mount light may then be attached to the proximal end of the channel retractor164so that the outer surface of the psoas muscle near the distal end of the channel retractor164is well lit. The proximal end of the channel retractor164may be adapted to allow the surgeon a choice of several locations for mounting the stadium mount light to the channel retractor164.

As nerves are in the psoas muscle and care is taken to avoid damaging the nerves, those of skill in the art understand the process of neuromonitoring to locate the positioning of the nerves. As neuromonitoring is not the focus of the present application, details on the process of neuromonitoring are not included here.

The top surface of the psoas muscle is split between the muscle fibers typically using a Penfield dissector or a Cobb dissector. Some surgeons may prefer a straight dissector, and some may prefer an angled dissector.FIG. 2shows an angled Cobb dissector176that may be used. The angled Cobb dissector176has a set of insertion depth markings180that may be used as an input by the surgeon to select components of the appropriate length for secondary retraction steps.

After the psoas muscle is split, some surgeons will choose to insert a 90 degree nerve retractor down the side of the dissector used to maintain the split in the psoas muscle.

A guide pin (not shown) may be inserted along the nerve retractor (or dissector) through the split in the psoas muscle into the interior of the targeted disc space. The distal end of the guide pin may be inserted five to ten millimeters into the disc space. Once the guide pin is positioned, the nerve retractor may be removed from the incision.

A lateral fluoroscopy image may be taken to confirm that the guide pin is in the anterior/posterior center of the disc space. If the guide pin is properly positioned, an A/P fluoroscopic view may be used to confirm that the channel retractor164is centered over the guide pin. Once the channel retractor164position has been adjusted to be centered over the centered guide pin, the guide pin may be removed.

Creating an Access Channel in the Psoas Muscle.

Enlarging the small opening created by the initial opening in the tough fibrous psoas muscle is challenging. The enlargement may be performed after the channel retractor164is properly aligned and provides a working channel from outside the patient to the edge of the psoas muscle. However, sufficient force needs to be applied to expand the psoas muscle and then the enlarged opening in the psoas muscle should be maintained as a working channel to the disc space to allow for the surgical procedure on the disc, such as a fusion procedure.

One way to achieve the task of opening the psoas muscle and maintaining the access channel is to use a tube in a tube assembly as taught in U.S. Pat. No. 8,795,167.

Tube in a Tube.

FIG. 3toFIG. 7illustrate the concept of a tube in a tube secondary retraction system. InFIG. 3, a cross section of a channel retractor204is shown. Channel retractor204has a circular rather than rounded rectangular cross section, other designs taught in the '167 included rounded rectangular shaped retractors. The channel retractor204has a closed inner perimeter that defines a working channel208through a first tissue from the proximal end212outside the patient to a distal end216placed adjacent to the edge of a second tissue such as the psoas muscle.

FIG. 4shows the cross section ofFIG. 3after the distal end portion232of a first extended retractor236is moved through the channel retractor204and into the opening made in the psoas muscle as described above.

FIG. 5shows the cross section ofFIG. 4after a distal end portion224of a second extended retractor228is moved through the channel retractor204and into the opening made in the psoas muscle. Notice that the first extended retractor236and second extended retractor228each have a first angle240between the distal end portion224,232for insertion into the psoas muscle and the intermediate portion248for traversing the channel retractor204. The intermediate portion248may be called the channel retractor portion. This obtuse first angle240allows the two distal end portions224and232to be substantially aligned for placement adjacent to one another in an opening in the psoas muscle. The first extended retractor236and the second extended retractor228each have a second angle256of approximately ninety degrees for placement at the proximal end212of the channel retractor204to allow a handle portion260for the first extended retractor236and second extended retractor228to be out of the way of the surgeon, so the surgeon can easily have direct visualization of the psoas muscle.

FIG. 6illustrates inserting an inner sleeve356into the channel retractor204to force the first extended retractor236and second extended retractor228to substantially opposite sidewall portions of the inner perimeter206of the channel retractor204to gradually and controllably spread the opening in the psoas muscle. In the most basic form (not shown here) the inner sleeve could be an appropriately sized hollow cylinder. The '167 showed embodiments of the inner sleeve that were U-shaped rather than a fully closed perimeter of a cylinder.

Note that the inner sleeve356has a retractor receiving indentation360that is visible in this view. A corresponding retractor receiving indentation is on the opposite side. The distal end of the inner sleeve356may include a bevel368.

FIG. 7is a top perspective view during insertion of the inner sleeve356to form an assembly with portions of the first extended retractor236and second extended retractor228sandwiched between the inner sleeve356and the inner perimeter206of the channel retractor204. Note that the first extended retractor236and the second extended retractor228may be inserted to different depths. For example, the extended retractor placed on the anterior side of the opening in the psoas muscle may need to extend further distally than the extended retractor placed on the posterior side of the opening in the psoas muscle, due to anatomical differences of the spine.

One of skill in the art will appreciate that an inner sleeve may be sized to push the first extended retractor and the second extended retractor outward from the centerline of the channel retractor, but not far enough to move both the extended retractors against the inner perimeter of the channel retractor. Some surgeons may prefer a smaller expansion of the second tissue and thus may not opt to fully expand the tissue. Conversely, a surgeon may opt for an initial partial expansion followed by a second expansion to push the extended retractors all the way to the inner perimeter of the channel retractor.

Notches324in the distal end216of the channel retractor204allow the distal end portions224and232of the extended retractors228and236to extend beyond the inner perimeter206of the channel retractor204when the extended retractors228and236are positioned elevated relative to a proximal face316of channel retractor204.

One of skill in the art will recognize that at the process step illustrated inFIG. 6, there are four primary components, channel retractor204, inner sleeve356, and extended retractors228and236. While the channel retractor may be secured with the table mounted retractor arm with a stabilization arm after being advanced distally down to the psoas muscle, this still leaves three primary components that are not fastened to anything as of the process step shown inFIG. 6. Three components are difficult to manage by one surgeon with only two hands. Having additional people hold one or more components is certainly possible but facilitating the process so that one person can handle the application of force to move the distal ends of the extended retractors would be an improvement to the prior art.

SUMMARY OF THE DISCLOSURE

This summary is meant to provide an introduction to the concepts that are disclosed within the specification without being an exhaustive list of the many teachings and variations upon those teachings that are provided in the extended discussion within this disclosure. Thus, the contents of this summary should not be used to limit the scope of the claims that follow.

Some of the teachings of the present disclosure may be summarized as an assembly for maintaining an extended access channel in tissue, the assembly having a channel retractor with a first gate track to receive a slide gate to press an extended retractor radially outward relative to the longitudinal centerline of the lumen such that when the first extended retractor has the distal portion extending beyond the distal end of the channel retractor and retaining tissue to provide the extended access channel inserting the first slide gate into the first gate track causes the distal portion of the first extended retractor to remain separated from the longitudinal centerline of the lumen to maintain the extended access channel.

Other teachings of the present disclosure include having a channel retractor that has at least one tab gap in a proximal face of the channel retractor to receive a corresponding tab from the first slide gate when the first slide gate is fully inserted into the first gate track so that a surgeon may subsequently pull on a distal face of the tab to remove the first slide gate from the channel retractor.

Other teachings of the present disclosure may be summarized as having a channel retractor with a second gate track to receive a slide gate to press a second extended retractor radially outward relative to the longitudinal centerline of the lumen within the channel retractor; such that when the first extended retractor and the second extended retractor have at least parts of their distal portions extending beyond a distal end of the channel retractor and inserted into an opening in tissue, inserting the first slide gate and second slide gates into the first gate track and second gate track causes the distal portions of the first extended retractor and the second extended retractor to remain separated from the longitudinal centerline of the lumen which may be used to maintain the opening in tissue distal to the distal end of the channel retractor.

The present disclosure teaches that the second slide gate may be located opposite from the first slide gate but is not required to be opposite. There may be more than two slide gates.

Some of the teachings of the present disclosure may be summarized as a method of providing an extended access channel to a portion of a spine of a patient for an extended access channel that traverses a path that was originally obstructed by a psoas muscle. The method includes:creating an access channel from outside the patient to the psoas muscle;placing a channel retractor to maintain the access channel from outside the patient to the psoas muscle;anchoring the channel retractor so that the channel retractor is immobile;moving psoas tissue located distal to a distal end of the channel retractor away from a longitudinal centerline of the channel retractor with a distal end of a first extended retractor to create the extended access channel; andretaining the psoas tissue away from a longitudinal centerline of the channel retractor with a first slide gate inserted into a first gate track integral to a first portion of an inner wall of the channel retractor to hold an intermediate portion of the first extended retractor against the first portion of the inner wall of the channel retractor to maintain the extended access channel to the portion of the spine of the patient.

The teachings of the present disclosure include both splitting the psoas and using a pair of retained extended retractors to maintain the extended access channel and using a single extended retractor to sweep tissue across the access channel and then retain the tissue with a single extended retractor.

The teachings of the present disclosure are not limited to use to extend an access channel across a psoas muscle to reach the spine. Other tissue may be retained by one, two, three or even more extended retractors for other surgical techniques. Thus the concept may be expressed as a method of providing an extended access channel through tissue.creating an access channel from outside a patient to a first depth in the patient;placing a channel retractor to maintain the access channel from outside the patient to the first depth;anchoring the channel retractor so that the channel retractor is immobile;moving tissue located distal to a distal end of the channel retractor away from a longitudinal centerline of the channel retractor with a distal end of a first extended retractor to create the extended access channel; andretaining the tissue away from a longitudinal centerline of the channel retractor with a first slide gate inserted into a first gate track integral to a first portion of an inner wall of the channel retractor to hold an intermediate portion of the first extended retractor against the first portion of the inner wall of the channel retractor to maintain the extended access channel.

The method may further include moving additional tissue located distal to the distal end of the channel retractor away from the longitudinal centerline of the channel retractor with a distal end of a second extended retractor; and retaining the additional tissue away from the longitudinal centerline of the channel retractor with a second slide gate inserted into a second gate track integral to a second portion of the inner wall of the channel retractor to hold an intermediate portion of the second extended retractor against the second portion of the inner wall of the channel retractor to maintain the extended access channel.

The second gate track is located directly across from the first gate track such that the second slide gate holds the second extended retractor directly across from the first slide gate with the held first extended retractor but this is not required.

There may be more than two extended retractors and slide gates engaged with a corresponding number of gate tracks.

Inventive concepts are illustrated in a series of examples, some examples showing more than one inventive concept. Individual inventive concepts can be implemented without implementing all details provided in a particular example. It is not necessary to provide examples of every possible combination of the inventive concepts provide below as one of skill in the art will recognize that inventive concepts illustrated in various examples can be combined together in order to address a specific application.

Other systems, methods, features and advantages of the disclosed teachings will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within the scope of and be protected by the accompanying claims.

DETAILED DESCRIPTION

The present application has a range of teachings that may be used to advantage in a number of settings. However, to provide these teachings with clarity, it is useful to describe one use of many of the teachings in great detail. The use described below is to access a lateral portion of a human spine using a lateral approach in order to provide therapy such as a fusion procedure to a vertebral motion segment. This process may be broken down to a natural sequence of:Positioning the patient,Creating an access channel to the psoas muscleCreating an opening through the psoas muscleEnlarging an access channel through the psoas muscle.Preparing the disc spaceDelivering an implant which may include fusion promoting materials.Closing the access path.

The psoas muscle is a major muscle in the human body used to stabilize the base of the spine. The psoas muscle is involved in hip flexion and rotation. The psoas muscle runs on both lateral sides of the lumbar spine. The psoas muscle is of interest for spine surgery in that this tough muscle must be traversed to access lumbar discs from a lateral approach.

Positioning the Patient.

Those of skill in the art are familiar with various techniques for positioning a patient to facilitate access to a spinal disc space from a lateral approach. This knowledge includes making adjustments as needed to provide access around the iliac crest for lateral access to the lumbo-sacral spine. Thus, this description will be brief and should be considered exemplary rather than limiting to the teachings of the present disclosure.

A patient may be positioned in a lateral decubitus position on a radiolucent breaking table. The patient may be stabilized and secured to the table with surgical tape:A) just below the iliac crestB) over the thoracic region;C) from the iliac crest to the knee, then secured to the table; andD) from the table to the knee, past the ankle, then secured back to the table.

Placing the table break at the iliac crest may work well when targeting the L3/L4 or L4/L5 disc spaces. When targeting the L1/L2 or the L2/L3 disc spaces it may be helpful to position the patient so that the table break is cephalad of the iliac crest. After positioning, a true Anterior/Posterior (A/P) image may be obtained of the targeted disc using a C-arm imaging device (not shown). Likewise a true lateral image may be obtained using the C-arm imaging device. A line in the anterior/posterior direction may be drawn on the patient to represent the midline of the targeted disc. Additional lines may be added to represent the front, back, and midline of the disc space in the lateral direction.

After conventional draping and preparation of the surgical site, a table mounted retractor arm (not shown) may be mounted to the table for use later in the process.

Access to Psoas.

Make an anterior-to-posterior incision over the center marking of the disc space. This incision may be 35 to 40 millimeters in length for some patients. The incision may be transverse, vertical, or oblique depending on preference.

Using finger or blunt dissection, open the incision down to fascia over the external oblique muscles. Incise fascia in line with the muscle fibers. Continue blunt or finger dissection through the muscle layers into the retroperitoneal space to the psoas muscle. After blunt or finger dissection has made a pathway to the psoas muscle, the access channel may be enlarged through conventional techniques such as a sequence of one or more dilation tubes of increasing diameter and decreasing length. The term enlarge is meant to include the various processes known in the art to increase the volume of an opening. This would include dilation, dissection, retraction, or combinations thereof, and analogous actions.

Depth indications on the outermost dilator may be used to select a channel retractor. For example the first outermost dilator has depth markings for 100 millimeters, 120 millimeters and 140 millimeters on one side along the longitudinal shaft of the outermost dilator. The surgeon notes the value of the marker closest to the patient's skin and selects a corresponding channel retractor (discussed below) to insert over the outer surface of the outermost dilator. The channel retractor is advanced distally down to the psoas muscle and then secured with the table mounted retractor arm with a stabilization arm. All of the tissue dilators are removed and a lateral fluoroscopic image is obtained to confirm placement of the channel retractor is centered over the targeted disc space. If the channel retractor is not centered, adjustments are made so that the channel retractor is positioned directly over the targeted disc.

FIG. 8shows channel retractor1204. The channel retractor1204may be connected to the operating table via one or more stabilizer arm1420. A pair of extended retractors1508and1512is shown protruding above the proximal end1212of the channel retractor1204and beyond the distal end1216of the channel retractor1204. The extended retractors1508and1512are shown without their removable handles which would be attached when manipulating the extended retractors1508and1512and then optionally removed to minimize obstructions near the proximal end1212of the channel retractor1204. FIG. 16 of U.S. Pat. No. 8,795,167 provides an example of removable handles.

A pair of slide gates1608and1612is shown in this figure but would not be present until they were in use. As discussed in detail below, once one or both extended retractors1508and1512are placed with their distal end portions1568into a slit in the psoas or other relevant tissue, the distal ends1624of slide gates1608and1612may be inserted into gate tracks1254(not shown here) in the channel retractor1204to force the extended retractors1508and1512radially outward from the longitudinal centerline of a lumen running through the channel retractor1204. This controlled outward pressure on the relevant extended retractor1508or1512from the paired slide gate1608or1612will increase as the slide gate (1608or1612) is inserted deeper into the gate track1254in the channel retractor1204.

Alternatively, once one or both extended retractors1508and1512are placed with their distal end portions1568in place to move tissue, the surgeon may use the distal end portion1568to move the tissue and then use the relevant slide gate1608or1612to hold the extended retractor1508or1512and engaged tissue out of the way of the extended access channel extending beyond the distal end1216of the channel retractor1204.

Note that one slide gate1608or1612may be introduced and inserted partway or fully into the track of the channel retractor1204. Then the other slide gate1608or1612may be inserted into the track of the channel retractor1204. Thus, at any one time, the surgeon need only address the position of one extended retractor508or1512and one slide gate1608or1612as the channel retractor1204is affixed to the surgical table via one or more stabilizer arms1420.

Note that the surgeon does not need to wait until both slide gates1608and1612are positioned in the relevant tracks of the channel retractor1204, before pushing down on both slide gates1608and1612so that pressure is applied at the same time to both extended retractors1508and1512to force open the slit in the psoas muscle or other tissue. Rather, the surgeon may insert an extended retractor (1508or1512) and then achieve a half split of the psoas by inserting the relevant slide gate1608or1612. The process may be repeated with the second extended retractor1508or1512and the second slide gate1608or1612to achieve a full split of the psoas muscle.

An alternative is to have the surgeon apply force to one or the pair of extended retractors1508and1512to force the psoas tissue open and then use the slide gates1608and1612only to retain the extended retractors1508and1512against the interior perimeter walls of the channel retractor1204.

FIG. 9shows a perspective view of the major components to provide a sense of relative size. The extended retractors1508and1512are longer than the channel retractor1204as the extended retractors1508and1512extend beyond both the proximal end1212of the channel retractor1204and the distal end1216of the channel retractor1204in order to hold tissue away from a longitudinal centerline of the extended access channel.

The slide gates1608and1612are shorter than the channel retractor1204but may be close to the length of the channel retractor1204.

FIG. 10shows a top perspective view of the channel retractor1204, extended retractors1508and1512, and a slide gate1608. Each of the extended retractors1508and1512has a lateral gap1544in the horizontal portions1548(best seen inFIG. 9). Although the lateral gaps1544are not required for use of the teachings of the present disclosure, the lateral gaps1544in the horizontal portions1548allow a removable handle (not shown here) to reversibly engage the extended retractors1508and1512so that the removable handle may be removed when not needed to reduce the number of items extending in the work area around the proximal end1212of the channel retractor1204. The lateral gap1544could be replaced with a radial gap that extends inward from the extreme end1546of the horizontal portion1548of each of the extended retractors1508and1512provided that an appropriate removable handle is adapted to engage the radial gaps.

Slide gate1608has a pair of tabs1630which fit into corresponding openings (tab gaps1240) in the proximal end1212of the channel retractor so that a fully inserted slide gate1608or1612does not extend above the proximal face1316of the channel retractor1204. The tabs1630serve as stops to prevent over travel during insertion of a slide gate1608or1612.

Each tab gap1240has an outer edge1244. The outer edge1244is selected so that the tab1630when seated in the tab gap1240extends laterally beyond the outer edge1244so that a user can push upward on the tab1630to lift the tab1630up and out of the tab gap1240to remove the slide gate1608or1612from the channel retractor1204.

Visible inFIG. 10are the outer ends1260of the gate tracks1254that receive the slide gates1608and1612.

FIG. 11shows a front, right, top perspective view of a channel retractor1204. Slide gate1612is fully inserted into channel retractor1204so that the tabs1630are fully inserted into tab gaps1240. The distal end portion1568of extended retractor1512is held out away from the centerline of the lumen that runs through the channel retractor1204.

Slide gate1608is partially inserted into gate track1254(best seen inFIG. 10). Tabs1630on slide gate1608are not yet seated in tab gaps1240. A working channel1208exists between the slide gates1608and1612.

FIG. 12shows a left, front, bottom perspective view of the assembly fromFIG. 11looking into the distal end1216of the channel retractor1204. Slide gate1612is fully inserted with tab1630inserted into tab gap1240but easily removed because the outer edge1244of the tab gap1240leaves a distal face1634of the tab1630exposed.

A set of radio-opaque markers1250may be placed in the channel retractor1204. The radio-opaque markers1250may be placed on the distal end1216of the channel retractor1204so that the radio-opaque markers1250are visible during fluoroscopy to help envision the placement of the distal end1216of the channel retractor1204to ensure that the working channel1208is aligned with the destination such as a particular disc space between two adjacent vertebrae. A fourth radio-opaque marker1250is not visible inFIG. 12as the fourth radio-opaque marker1250is obscured by the distal end of extended retractor1508.

FIG. 13is provided purely for the purpose of helping to explain the relationship of components in the new access system.FIG. 13has the channel retractor1204and stabilizer arm1420rendered invisible to allow an unobstructed view of fully inserted slide gates1608and1612and the captive extended retractors1508and1512. As indicated by the positions of the radio-opaque markers1250which are embedded in the distal end1216of the channel retractor1204(rendered invisible), the distal end portions1568of the extended retractors1508and1512extend beyond the distal end1216of the channel retractor1204. The fourth radio-opaque marker is hidden behind the distal end portion1568of extended retractor1512.

Single Retractor Posterior Sweep of Psoas.

The anatomy of the psoas muscle differs from patient to patient and within a single patient, the width of the psoas muscle decreases towards the cephalad end of the psoas muscle. In some instances, a surgeon may prefer to sweep a thin layer of psoas muscle from the anterior side of the channel retractor1204to the posterior side of the channel retractor1204as this will provide a better clinical solution than attempting to split and work with a relatively thin portion of psoas muscle.

The surgeon would place the distal end portion1568of an extended retractor1508beyond the distal end1216of the channel retractor1204to engage an anterior edge of the psoas muscle while the horizontal portion1548of the extended retractor extends posteriorly out of the proximal end1212of the channel retractor1204. The surgeon would apply pressure and sweep the distal end portion1568and the engaged edge of the psoas muscle posteriorly towards the posterior side of the channel retractor1204. Once the psoas muscle has been moved, a slide gate1608may be engaged in the gate track1254on the posterior side of the channel retractor1204to retain the psoas muscle.

For surgeries at some levels of the spine, a surgeon may prefer to use two retractors and split the psoas for one patient but later that day may find during a lateral procedure that at the same level of the spine for another patient, it is preferable to use a single retractor posterior sweep. The channel retractor1204with a pair of gate tracks1254allows this decision to be made after the channel retractor1204has been put into place and stabilized by a connection to the operating table.

Mid-Process Adjustments to Maintain a Psoas Split.

One of the advantages of using a channel retractor1204with a pair of gate tracks1254and a pair of slide gates1608to hold a pair of extended retractors1508and1512is that mid-procedure a surgeon may release one extended retractor by removing the relevant slide gate1608so that the psoas muscle can be swept back out of the way with the extended retractor and then maintained by reinserting the slide gate1608. For various reasons, there can be muscle creep which causes previously positioned psoas muscle to creep back into the access path. There is an advantage of the individuated control of the extended retractors1508and1512by individual slide gates1608rather than by the use of an inner sleeve (See inner sleeve356inFIG. 6) as the use of the inner sleeve results in releasing both extended retractors and allowing the psoas tissue on both sides of the split in the psoas to be released. Once both sides have been released there will again be a need for three hands to hold a pair of extended retractors and insert the inner sleeve to hold the extended retractors away from the extended access channel.

One choice for material for use in the various channel retractors shown above is medical grade Radel® R5500 (Polyphenylsulfone). This material can withstand sterilization techniques such as Ethylene oxide (EtO) gas, radiation, steam autoclaving, dry heat, and cold sterilization. Other desirable attributes are that the material is dimensionally stable and may be marked with lasers. One of skill in the art will recognize that other materials could be used instead of Radel® R5500. PEEK is another material choice that may be used as it is radiolucent. Composites of carbon fibers and polymers may be selected for creating channel retractors or extended retractors.

Provision of Therapy after Creating an Access Channel.

After creating an access channel first to the psoas muscle then through the psoas muscle using any of the methods described above, a lateral portion of the spine may be accessed for the provision of therapy. One form of therapy is to fuse two adjacent vertebrae together. Some surgeons provide the therapy of spinal fusion without using an implant. Other surgeons use a spinal implant in the process of providing therapy to achieve spinal fusion. Spinal fusion typically involves the use of osteogenic, osteoconductive, or osteoinductive material (bone graft). Bone graft is the material that is used to promote bone growth and forms the scaffold that bridges the adjacent vertebral bodies comprising a motion segment in the spine. Two fused vertebrae do not move with respect to one another.

It is useful to have one name for the variety of materials used to promote fusion. Thus, fusion promoting materials include osteogenic, osteoconductive, and/or osteoinductive material including bone graft material whether the material is autograft or allograft and various bone graft substitutes or bone graft extenders. Various techniques for promoting effective fusion of adjacent vertebrae are well known to those of skill in the art so a minimal summary is sufficient for this document.

Preparation of Disc Space

One process to promote fusion is to conduct a discectomy to remove nucleus pulpous of the disc and to abrade the vertebral endplates adjacent to the disc space as bleeding from the endplates promotes bone growth and fusion. An interbody implant (sometimes called a fusion cage) may be introduced into the disc space along with quantities of a fusion promoting material such as an autograft or any other materials approved for such use. Frequently, the nature of the access channel used to access the disc space will impact the dimensions of the cage that may be delivered to the disc space.

Frequently, tools are inserted that serve as trial implants. These tools provide guidance to the surgeon on the most appropriate size of implant to use for a particular patient's anatomy for a particular access route. The position of the trial implant may be assessed via fluoroscopy. One dimension that may be ascertained by trial devices is the appropriate choice of height for the implant. In some instance it may be that assertive insertion of a series of progressively larger trial devices will serve to increase the distance between adjacent vertebrae (vertebral distraction) which may be a desired outcome of the surgical intervention.

There are other forms of therapies that may be provided to the spine and the methods of providing access set forth above are not limited to the provision of any one particular therapy.

ALTERNATIVES AND VARIATIONS

While the disclosure showed the used of interchangeable extended retractors and interchangeable slide gates that fit into the gate tracks on each side of the extended retractor, this is not a requirement of the present disclosure. While those of skill in the art will appreciate that having interchangeable parts reduces certain costs for manufacturing and inventory, it is not a requirement in order to enjoy the benefits of the present disclosure.

While the slide gates shown are designed so that when fully inserted the proximal face of the slide gate is not higher than the proximal face of the channel retractor, this is not required. For example the slide gates may not have the tabs1630that fit within the tab gap1240to facilitate removal of the slide gates. The slide gates may have a handle or a removable handle that is used to remove the slide gates from a fully inserted position into the gate track.

Number and Orientation of Slide Gates.

While the examples set forth above had a channel retractor with a pair of gate tracks located on opposite sides of the channel retractor, this is not a requirement in order to enjoy many of the benefits of the teachings of the present disclosure. While the channel retractor with a single pair of gate tracks to hold a pair of extended retractors with a pair of slide gates is well suited for maintaining a split in the psoas muscle, other surgical procedures may find that other arrangements of extended retractors and slide gates in gate tracks are useful for maintaining an extended access channel. An extended retractor may have four gate tracks to afford the surgeon an option to decide mid-procedure whether to use one pair of gate tracks on opposite sides of the channel retractor or use another set of gate tracks rotated 90 degrees from the first pair to allow tissue to be retained in one of two orientations.

It may be useful to use more than two extended retractors to hold back tissue for certain surgical approaches, perhaps with larger diameter channel retractors so a set of gate tracks may be provided in a channel retractor to allow three, four, or more extended retractors to be used and retained to maintain an extended access channel.

One of skill in the art will recognize that some of the alternative implementations set forth above are not universally mutually exclusive and that in some cases additional implementations can be created that employ aspects of two or more of the variations described above. Likewise, the present disclosure is not limited to the specific examples or particular embodiments provided to promote understanding of the various teachings of the present disclosure. Moreover, the scope of the claims which follow covers the range of variations, modifications, and substitutes for the components described herein as would be known to those of skill in the art.

The legal limitations of the scope of the claimed invention are set forth in the claims that follow and extend to cover their legal equivalents. Those unfamiliar with the legal tests for equivalency should consult a person registered to practice before the patent authority which granted this patent.