Patent Description:
The spine is a flexible column formed of a plurality of bones called vertebrae. The vertebrae are hollow and piled one upon the other forming a strong hollow column for support of the cranium and trunk. Various spinal disorders such as scoliosis, neuromuscular disease, and cerebral palsy may cause the spine to become misaligned, curved, and/or twisted or result in fractured and/or compressed vertebrae. It is often necessary to surgically correct these spinal disorders to straighten or adjust the spine into a proper curvature.

Generally the correct curvature is obtained through surgical procedures by manipulating the vertebrae into their proper position and securing that position with a rigid system of screws, rods, intervertebral spaces, and/or plates. During the surgical procedure, a tissue retractor may be inserted into a surgical incision to pull tissue away from the surgical site thus enlarging the viewing area for the surgeon. Tissue retractors form a surgical corridor including a proximal opening at the incision and a distal opening near the surgical site. Various instruments and implants may be inserted through the corridor. Exemplary tissue retractors may be found in <CIT> and <CIT>.

The amount of tissue to be retracted depends upon the chosen approach as well as various patient characteristics. For example, in a lateral approach, more soft tissue may be present between the surgical incision and the surgical site near the vertebrae than in a posterior approach. Patient anatomical differences may also require various length retractors. The size, shape, and configuration of the retractor may be chosen based on these as well as other factors.

Typical tissue retractors include two or more elongated blades with proximal ends attached to a housing that is in turn attached to a surgical table. Each blade assembly may be attached to a separate portion of the housing and include various adjustment features for manipulating the blades to adjust and enlarge the viewing area. Often, the tissue retractor may hold the blades close together in a tubular configuration for concentric insertion over dilation tubes along a common longitudinal axis. The portions of the housing may translate or rotate relative to one another to gradually pull the blades apart from one another to expand the surgical wound.

When a retractor is opened to distract soft tissue the resistance load pressing on the distal end of the blades increases and causes conical deformation. As used herein "conical deformation" is when the distal end of the blades curve back towards the center of the portal opening forming a cone-like shaped tunnel where the distal opening at the exposed surgical site is smaller than the proximal portal opening. The conical deformation of the blades also causes a reaction force that pushes the retractor away from the surgical site. This requires that the surgeon take extra precaution to prevent the blades from lifting off the bone surface as the retractor is opened.

In order to compensate for blade conical deformation most retractors use a secondary adjustment mechanism. This mechanism typically provides an independent pivot action to cause the distal end of the blade to project further out radially with respect to the proximal end of the blade-a motion referenced herein as "toeing out" or "toe out. " The blade may toe out by turning a screw that acts on a lever or by using a biased torsional spring. To properly align the opened retractor the surgeon is required to make two independent adjustments for each blade requiring additional surgical time, and adds complexity and bulk to the jaws of the retractor. Due to the limited area available in the jaw area the adjustment mechanisms must be compact which limits the leverage available to counteract the torque generated by long length blades. This lack of adequate counter leverage leads to very large loads that are applied to small mechanisms. Failure and wear of the secondary blade mechanism is a common complaint for such retractors. Accordingly, there exists a need in the art to provide a soft tissue retractor that adequately compensates for the conical deformation of the blades during a procedure.

Furthermore, successful surgery is performed when using these retractors by preventing soft tissue from encroaching into the surgical site by slipping under the distal end of the blade. The prime factor in managing the dissection of soft tissue is maintaining contact of the distal end of the blades with the surface of the bone to prevent tissue encroachment. However, maintaining blade contact is difficult because the bone structure has a complex surface geometry that may cause the blade to lift as the blades are spread apart.

To reduce the risk of complications, current retractor systems rely on docking and stabilization of the retractor rigidly with at least one surgical table arm. It is often necessary for the surgeon to remove and replace a blade with a blade of a different length to accommodate the varying bone structure. This replacement is often required at the L4/L5 disc space where the retractor frame may have to be tilted to avoid contact with the iliac crest. Replacing a blade during a procedure adds time.

Adjustment mechanisms of the prior art have attempted to address the blade contact issue by the use of shims that project beyond the end of the blade and contact the bone surface. The shims are fit into a groove in the blade and slide down the entire length of the blade. This structure provides the disadvantage of requiring the use of a separate component that has to be mounted to an insertion instrument.

Another system to provide blade adjustment is the use of a telescoping blade that uses a nested blade that can be extended to the required length. However, this method of using nested blades increases the blade cross-sectional area causing a more bulky blade system that requires larger initial dilation and increased tissue expansion for an aperture during a procedure.

Accordingly, there exists a need in the art to provide a soft tissue retractor providing for depth adjustment to prevent encroachment of soft tissue during a procedure. <CIT> relates to surgical retractors and methods of minimally invasive surgery. <CIT> relates to a medical retractor device. <CIT> relates to a cam-wedge locking mechanism. <CIT> relates to a surgical spreading instrument. <CIT> relates to. <CIT> relates to a retractor. <CIT> relates to a surgical retractor device and method of use. <CIT> relates to a tissue retractor and method of use. <CIT> relates to a speculum.

Provided herein are retractors configured to compensate for blade conical deformation, and a blade having an adjustment mechanism configured to adjust the depth of the blade so as to reduce the need for a shim.

In one embodiment, a tissue retractor includes a frame having at least one cam. The at least one cam is operatively connected to at least one cam follower. The cam follower may be a flat surface of a lever. The lever has a blade. The blade is disposed on a distal end of the lever, and is generally orthogonally to the lever and is in a fixed relationship to the cam follower. In some instances, the tissue retractor has at least two levers and each lever has a blade disposed on a distal end. The cam follower follows the cam so as to drive a distal end of respective blades away from each other as a respective proximal end of the at least two levers are squeezed towards each other. Accordingly, squeezing the levers together simultaneously opens a surgical corridor and causes the blades to toe out.

The frame may include a flange extending away from the frame towards the levers. The cam is mounted to the flange. The cam is mechanically coupled to a portion of a lever and is configured to guide the lever along an arcuate path so as to move the distal end of the blades away from each other. The arcuate path is generally orthogonal to a diameter of the surgical corridor. The curved geometry of the outer surface of the cam permits the rotation of the cam follower abutting the cam to result in rotation of the blade. Accordingly, a pair of cam followers bias against a pair of cams and the distal ends of the blades toe-out to compensate for blade conical deformation. The arcuate path is disposed generally along a radius generally orthogonal to the respective levers, and accordingly, the distal end of a blade travels radially further than the proximal end of the blade when the levers are squeezed together.

In other embodiments, the cam follower is directly connected to an arm of a ring retractor. Knobs corresponding with each arm and blade are adapted to rotate the arms and urge the cam followers along the cam to produce toe-out.

One example embodiment includes a frame with a plurality of flanges. Yet in another embodiment, the frame is a ring structure having a plurality of bores. Accordingly, the cam and cam follower automatically compensate for the increasing load on the distal ends of the blades when the blades are expanded in the tissue.

A blade having a blade adjustment mechanism allowing for adjustment of the depth of the blades of the tissue retractor is also provided. In such an embodiment, the retractor includes a lever having a housing adapted to connect with the adjustment mechanism. The adjustment mechanism includes a threaded portion formed on the blade. The adjustment mechanism further includes an adjustment screw, at least a portion of the adjustment screw is threaded, and the adjustment screw connects the blade to the lever. The threaded portion of the blade is mechanically coupled to the threaded portion of the adjustment screw wherein rotation of the adjustment screw displaces the blade in a vertical arrangement thereby allowing for adjustment of the depth of the blade. Furthermore, a spring loaded lock is connected to the threaded portion of the adjustment screw, the lock movable with the adjustment screw during depth adjustment.

Accordingly, the blades may be adjusted in depth so as to eliminate the use of shims. Further, the depth adjustment mechanism is disposed on the blade itself and integrates with the blade locking mechanism thereby minimizing the size of the retractor so the surgeon has the maximum amount of visualization when taking photos or performing a procedure.

The following detailed description of the illustrative embodiments can be better understood when read in conjunction with the following drawings where like structure is indicated with like reference numerals and in which:.

A retractor configured to compensate for blade deformation is provided. A blade having an adjustment mechanism is also provided. The blade is configured to mount to a housing of a lever so as to adjust the depth of the blade.

In a first embodiment, the tissue retractor includes a frame having at least one cam. The cam is operatively connected to a cam follower. The cam follower and a lever are in a fixed relationship with respect to each other. A blade is fixedly mounted to the distal end of the lever and is generally orthogonally to the lever. Accordingly, the blade is also in a fixed relationship with the cam follower.

In some instances, the tissue retractor has two levers and squeezing the levers results in simultaneous opening and "toeing-out" of the blades. Namely, each lever urges a cam follower along a cam so as to drive a distal end of the blades away from each other as the surgical corridor is formed. Each cam is mechanically coupled to a given blade and includes a curved surface configured to guide a given cam follower and the blade wherein the blade may compensate for the load exerted by the tissue. In another embodiment, two offset cams are provided to facilitate the toe-out motion. The tissue retractor eliminates the need for bulky secondary blade mechanisms to counteract undesired blade deformation at the surgical site.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to a "lever" is a reference to one or more levers and equivalents thereof known to those skilled in the art, and so forth.

The words proximal and distal are applied herein to denote specific ends of components of the instrument described herein. A proximal end refers to the end of an instrument nearer to an operator of the instrument when the instrument is being used. A distal end refers to the end of a component further from the operator and extending towards a surgical area of a patient and/or the implant.

Now referring to <FIG>, a tissue retractor having at least two levers is provided. The lever actuated tissue retractor <NUM> includes a first lever <NUM>, a second lever <NUM>, a frame <NUM>, and a plurality of blades <NUM>. As shown in <FIG> the tissue retractor <NUM> includes a cam <NUM> having a cam surface <NUM>. <FIG> shows the tissue retractor having two pair of cams <NUM>, i.e. an upper cam 151a and a lower cam 151b, operatively coupled to each lever <NUM>, <NUM>. The pair of cams 151a, 151b are offset each other on a respective side of the frame <NUM>. Each cam 151a, 151b includes respective cam surfaces 153a, 153b for which a respective cam follower 155a, 155b follows. However, it should be appreciated that the illustrations provided herein are not limiting to the scope of the appended claims and that the tissue retractor may be configured to have only one cam <NUM> on each side of the frame <NUM> coupled to a respective lever <NUM>, <NUM>. In such an embodiment where only one cam <NUM> is used, it should be appreciated that the geometry of the cam surface <NUM> along with the positioning of the cam <NUM> with respect to the blade <NUM> and the length of the blade <NUM> will determine the arc length and the range of motion of the toe-out of the distal end of the blade <NUM>.

The cam surface <NUM> is mechanically coupled a respective cam follower <NUM>. The cam surface <NUM> is generally curved and configured to generate a toe-out movement of the blade <NUM>. The blades <NUM> may be opened and closed relative to each other by squeezing the first lever <NUM> and second lever <NUM> towards each other. It should be appreciated that, operation of one cam and cam follower need only be described, as the operation of the other cam and cam follower is the same.

The cam <NUM> is mechanically coupled to a cam follower <NUM>. The cam follower <NUM> is generally disposed at the proximal end of the blade <NUM>. The cam <NUM> includes a curved cam surface <NUM> for which the cam follower rides <NUM> along and is guided along the path of the cam surface <NUM>. Accordingly, the blade toes outs so as to compensate for the load exerted by the tissue. In one embodiment, two offset cams <NUM> are provided to facilitate the toe-out motion.

The cam follower <NUM> is urged along respective cams 151a, 151b and cam surfaces 153a, 153b. In other embodiments, a plurality of cams <NUM> are provided. In this embodiment, the cam follower <NUM> directly connects to the cam <NUM> without the use of pivot posts and spherical elements (such as discussed below). The cam follower is adapted to connect and move directly on the cam surface <NUM>.

The cam follower <NUM> is operatively connected to the cam surface <NUM>. <FIG> provide an illustrative example of a means for connecting the cam follower <NUM> to the cam <NUM>. A first pivot post <NUM> and a second pivot post <NUM> extend from opposing surfaces of a lever <NUM>, <NUM>. A plurality of spherical elements <NUM> are disposed at the distal end of the pivot posts. In this particular embodiment, the spherical elements <NUM> are spherical bushings that surround the distal end of the first pivot post <NUM> and the second pivot post <NUM>. The pivot posts <NUM>, <NUM> and the spherical elements <NUM> help facilitate the connection between the cam <NUM> and the cam follower <NUM>.

The first pivot post <NUM> and the second pivot post <NUM> are offset in relation to one another in the same offset relation as the respective cams <NUM>. The first pivot post <NUM> and the second pivot post <NUM> also are offset in relation to one another in a distal and proximal direction along a portion a length of the first lever <NUM> by an offset length L, such as shown in <FIG>. The first post <NUM> is disposed distal to the second post <NUM> by offset length L. As shown in <FIG> the first and second pivot posts are disposed near the distal end of the first lever <NUM>. Also shown in <FIG> is the second lever <NUM>. The second lever <NUM> may be a mirror image of the first lever <NUM> with corresponding pivot posts, spherical elements <NUM>, cam <NUM>, cam surface <NUM> and cam followers. In other embodiments not shown, the second lever <NUM> may not be a mirror image of the first lever <NUM> such as having a different offset length between the pivot posts. In yet other embodiments, the second lever <NUM> may be an elongated extension of frame <NUM> or otherwise attached to frame <NUM> such that the lever is immobile.

The frame <NUM> includes a plurality of flanges <NUM> extending outwardly from opposite sides of the frame <NUM>. The plurality of flanges <NUM> are positioned such that the first lever <NUM> and the second lever <NUM> can be positioned in a space between the flanges <NUM>. Furthermore, the flanges <NUM> have pivot sockets <NUM> corresponding to the first pivot post <NUM> and second pivot post <NUM> for both the first lever <NUM> and second lever <NUM>. The cam surface <NUM> is disposed on the distal end of the respective flanges.

In one embodiment the pivot sockets <NUM> house the spherical elements <NUM> to create a plurality pivot points <NUM> that are ball-and-socket joints as shown in <FIG>. The pivot points <NUM> in this particular embodiment are ball-and-socket joints and thus providing independent and multi-axial movement at each pivot point <NUM> allowing the cam follower <NUM> to follow the arcuate path of the cam surface <NUM>. In embodiments not shown, the pivot posts may be cast or welded with spherical elements <NUM>.

In another embodiment not shown, the plurality of flanges <NUM> may extend along the length of the frame <NUM>. Although the flanges <NUM> of the exemplary embodiment of <FIG> extend away from the frame <NUM> at right angles, one of ordinary skill in the art necessarily understands that various flange geometries can be implemented provided that the flange provides proper structural support for the offset pivot points <NUM> and the desired lever motion.

A plurality of blades <NUM> shown in <FIG> are attached to the distal ends of the first and second levers <NUM>. In other embodiments, only one (or more than two) blade(s) <NUM> are used. The blades <NUM> may be attached by welding or may be cast as a continuous extension from a given lever.

The plurality of blades <NUM> may be positioned at any angle relative to the first and second levers <NUM>, <NUM>. In this particular embodiment shown in <FIG>, the plurality of blades <NUM> are perpendicular to the first and second levers <NUM>, <NUM>. In other embodiments, the plurality of blades <NUM> may have a more acute or more obtuse angle.

The plurality of blades <NUM> in a first position form a surgical corridor, which may be used with other medical instruments such as, for example, a dilator. In the first position, the blades <NUM> may be inserted over the dilator. As the proximal ends of the first lever <NUM> and second lever <NUM> are squeezed together, the distal ends of the levers will simultaneously spread apart and rotate in a multi-plane motion causing the top and bottom sides of the levers <NUM>, <NUM> to follow separate arc lengths and provide simultaneous opening and toeing action to the plurality of blades <NUM>. Movement of the plurality of blades <NUM> away from each other will result in opening the surgical corridor and in a toe angle <NUM> in a second position, as shown in <FIG>. The offset length L between the cams determines an opening angle <NUM> and toe angle <NUM>. The amount of toe angle <NUM> generated is a sinusoidal relation to the opening angle <NUM> which increases in gain as the opening angle increases.

The length L of pivot offset as shown in <FIG> can be adjusted to adjust blade deflection so that a parallel or a toed out condition will exist when the blades are fully opened. The bottom arc length Lb and the top arc length Lt (shown in <FIG>) may also be adjusted to adjust blade deflection. Deflection is the amount that the blades are displaced axially with respect to each other. Specifically, the amount the blades are displaced during a procedure when soft tissue exerts a force against the blades.

The illustrative embodiments described depict uniform sized spherical elements <NUM> and pivot pocket opening sizes. It is necessarily apparent to one of skill in the art that various combinations of spherical element <NUM> size, pivot pocket opening sizes, cam surface geometry and cam follower geometry may be implemented to achieve the desired opening angle and tilt angle required for various circumstances.

In an embodiment not shown, the lever actuated tissue retractor device <NUM> may also include a biasing mechanism to return the plurality of blades <NUM> to the first position (<FIG>) or may be biased to return the plurality of blades <NUM> to the second position (<FIG>). For example, a spring may be positioned between the first lever <NUM> and second lever <NUM> such that upon relieving the compression force the levers will actuate the tissue retractor device to the first position.

Also not shown, is an embodiment that includes a lock mechanism displaced between the levers that can retain one or more open positions. In one embodiment, the lock mechanism can be a ratchet assembly. In another embodiment the lock mechanism can be opposing elongated members with corresponding serrations that interact to retain an open position. In yet another embodiment, the lock mechanism is combined with the biasing mechanism such that the tissue retractor device will automatically close with the release of the lock mechanism or vice versa automatically open with the release of the lock mechanism. Alternatively, the lock mechanism can be similar to the lock mechanism illustrated in <FIG>.

Furthermore, the illustrative embodiment described changes to the geometry of the cams <NUM> along one axis. However, one of ordinary skill in the art necessarily understands that the geometry of the cams <NUM> may be changed along two axes to tailor the path of the tilting motion relative to the blade opening as desired. Along with the geometry of the cam surface <NUM>, the length of the plurality of blades <NUM> will determine the arc length exhibited by the distal ends of the blades <NUM> as well as the amount of torque required to displace the tissue at the surgical site. Thus, blades of various sizes both uniform and non-uniform are contemplated within the scope of the present invention.

It should also be appreciated that the tissue retractor <NUM> may include multiple blades <NUM>. For example, the cam <NUM> and cam follower <NUM> may be used in a three blade <NUM> configuration by having a central blade (or posterior blade) mounted to the frame <NUM>. This embodiment would be similar to the blade configuration as shown in <FIG>.

Now referring to <FIG> another embodiment of a tissue retractor <NUM> having a ring frame <NUM> is provided wherein the like elements are referenced by like numbers increased by <NUM>. The tissue retractor <NUM> includes the ring frame <NUM>, a plurality of drive assemblies <NUM>, at least one arm <NUM> and a plurality of blades <NUM>. Each blade <NUM> is connected in a generally orthogonal arrangement to a respective arm <NUM>. The tissue retractor <NUM> includes at least one cam <NUM> and respective cam surface <NUM> (<FIG>). A cam follower <NUM> is coupled to the cam surfaces <NUM> of the cam <NUM>.

The cam <NUM> includes the cam surface <NUM> which is curved along a radius generally orthogonal to the plane of the ring frame <NUM> and thus is configured to guide a respective blade <NUM> to toe out wherein the blade <NUM> may compensate for the load exerted by the tissue.

The cam <NUM> and cam follower <NUM> are coupled together by a first and second pivot post. The first and second pivot post <NUM>, <NUM> allow the cam follower <NUM> to rotate, move and pivot about the cam surface <NUM>. Accordingly, the cam follower <NUM> may follow the cam surface <NUM>.

In this embodiment, the cam follower <NUM> connects to an arm <NUM>. The arm <NUM> includes a blade <NUM> fixedly mounted to a free end of the arm <NUM>. The arm <NUM> is configured to swing inwardly within the ring frame <NUM>. As the arm <NUM> swings inwardly, the cam follower <NUM> follows the cam surface <NUM> resulting in a toe-out motion of the blades <NUM>.

The ring frame <NUM> may also include a boss <NUM> to enable the attachment of the ring frame <NUM> to a stabilization surgical arm (not shown). The stabilization surgical supports the retractor during surgery.

An illustration of a drive assembly <NUM> is shown in <FIG> and <FIG>. The drive assembly <NUM> includes a knob <NUM> coupled to barrel <NUM> by having internal threads corresponding to the threads on the proximal end of barrel <NUM>. In other embodiments, the knob <NUM> is coupled as a snap on piece to the proximal end of barrel <NUM> or the knob <NUM> may be glued, welded, or cast as part of barrel <NUM>.

The barrel <NUM> is retained in bore <NUM> which essentially acts as a bushing allowing barrel <NUM> to rotate around a longitudinal axis <NUM>. As such, barrel <NUM> may include bearings or any other structure that is conducive to rotation. The diameter of bore <NUM> is such that the rotation of barrel <NUM> remains substantially on a single longitudinal axis <NUM>. The distance between collar 213a and detachable collar <NUM> is such that the lateral movement of barrel <NUM> is prevented.

The barrel <NUM> has internal threads that correspond to the threads on a clevis engagement piece <NUM> such that rotation of barrel <NUM> actuated by knob <NUM> results in the translation of the rotational movement of barrel <NUM> to lateral movement of the clevis engagement piece <NUM> and the clevis <NUM> in the proximal and distal direction along longitudinal axis <NUM>. In other embodiments not shown, lateral movement of the clevis may not require a threaded barrel. For example, knob <NUM> may have a central bore with corresponding threads to clevis engagement piece <NUM> obviating the need for a threaded barrel. In other embodiments of the drive assembly <NUM>, the knob <NUM> may be omitted and instead the clevis engagement piece <NUM> may be elongated threaded piece or a rack such that the clevis <NUM> can be actuated by a ratcheted pinion or coupled to another device. It is necessarily apparent to one of ordinary skill in the art that the drive assembly <NUM> embodiment for imparting the described motion is only for illustrative purposes, and all structures that impart similar motions are contemplated within the scope of the present invention.

The clevis <NUM> is coupled to the arm piece <NUM> via a pivot pin <NUM> hinging a clevis knuckle <NUM> with an arm piece knuckle <NUM> to create an elbow-like joint or hinge. The pivot pin <NUM> in this particular embodiment passes through a track <NUM> to facilitate controlled movement of clevis <NUM> along longitudinal axis <NUM>. The pivot pin <NUM> in other embodiments not shown may be a quick pin or any similar type of pin which enables detachability of the arm piece <NUM>. The clevis <NUM> in this particular embodiment incorporates a yoke-type conformation wherein the arm piece knuckle <NUM> is disposed within the clevis knuckle <NUM>. The pivot pin <NUM> is passed through the clevis <NUM> and knuckle <NUM>, thereby securing the clevis <NUM> to the knuckle. The knob <NUM> may be rotated so as to urge the clevis <NUM> forward, however the pin <NUM> translates the forward advancement of the clevis <NUM> into rotational movement, wherein the knuckle <NUM> and the arm piece <NUM> swing outwardly as one piece, carrying the blade <NUM>. In other embodiments not shown, the pivot pin <NUM> may be a grommet wherein the clevis knuckle <NUM> does not have the yoke-like conformation as shown in <FIG>. Other embodiments wherein the clevis knuckle <NUM> does not have a yoke-like conformation are fully contemplated within the scope of the present invention provided that the desired hinge can be achieved.

The arm piece <NUM> in this embodiment includes a first pivot post <NUM> and second pivot post <NUM> which are offset from each other. The first pivot post <NUM> includes the cam <NUM> having a generally curved surface. The second pivot post <NUM> includes the cam follower <NUM> having a generally curved surface. The cam <NUM> is fixedly mounted to an end portion of the first pivot post <NUM> and the cam follower <NUM> is fixedly mounted to an end portion of the second pivot post.

Now referring to <FIG> which illustrate the bottom view of ring frame <NUM> and <FIG> which illustrates the top view of ring frame <NUM>, the arm piece <NUM>. The first and second spot face <NUM>, <NUM> have an aperture 233a through which the first pivot post <NUM> passes through. The arm piece <NUM> has a yoke-like structure with two prongs 224a, 224b having respective apertures 224c, 224d (<FIG>). The spot faces <NUM>, <NUM> fit within the prongs 224a, 224b of the arm piece <NUM>. The first and second pivot posts <NUM>, <NUM> are inserted into respective apertures 224c, 224d. The apertures 224c, 224d are offset from each other with respect to a longitudinal axis of the arm piece <NUM>. Aperture 224d is aligned with aperture 233a wherein the first pivot post <NUM> is mounted therein. The end of the first pivot post <NUM> includes a cam <NUM> having a cam surface <NUM> and the end of the second pivot post <NUM> includes a cam follower <NUM>. The cam <NUM> and cam follower <NUM> are disposed within the interior of the yoke-like arm piece <NUM>. The cam <NUM> and cam follower <NUM> may or may not each have a threaded bore configured to receive threaded ends (not shown) of respective first and second pivot posts <NUM>, <NUM> so as to couple the arm piece <NUM> to ring frame <NUM> such that the cam <NUM> and cam follower <NUM> are mounted to their corresponding pivot sockets wherein the cam follower <NUM> is pressed against the cam surface <NUM>. Accordingly, opening of the blade <NUM> urges the cam follower <NUM> along the arcuate path of the cam surface <NUM> causing the distal end of the blade <NUM> to toe out as the blade <NUM> is opened. It should be appreciated that the blade <NUM> may be opened by rotating knob <NUM> as described above.

The tissue retractor <NUM> may further include a blade locking mechanism <NUM> by which the blade <NUM> is coupled to the arm piece <NUM>. In the example embodiment shown in <FIG> and <FIG>, the blade locking mechanism <NUM> includes a slot 228a, a latch 228b, a latch slot 228c, a locking pin 228d, and a set pin 228e. The engageable end of latch 228b is inserted into latch slot 228c and coupled to the locking pin 228d by disposing a set pin 228e through aligned openings on the latch 228b and locking pin 228d. The latch 228b or locking pin 228d is biased such that the locking pin 228d protrudes into the stub receiving slot 228a until the latch 228b is actuated to withdraw the locking pin 228d from the stub receiving slot 228a. The distal end of the locking pin 228d is angled as shown in or rounded such that a blade tang <NUM> can slide into the stub receiving slot 228a and be secured as the locking pin 228d sets into a notch on the blade tang <NUM>. In other embodiments not shown, the blade is welded or is part of a continuous cast of the arm piece <NUM>.

An isolated view of the arm piece knuckle <NUM> attachment point 221a and clevis <NUM> is provided in <FIG>. The ring frame <NUM> is purposefully omitted to show that the knuckle <NUM> may be configured to provide a degree of freedom at the hinge region allowing the arm piece <NUM> to exhibit the desired range of motion. In one embodiment, the attachment point 221a is an orifice with a diameter greater than that of the pivot pin <NUM>. In other embodiments, the attachment point 221a may be comprised of flexible material. One of ordinary skill in the art necessarily understands that the attachment point 221a can be any structure that provides the degree of freedom to allow the arm piece <NUM> to exhibit movement resulting in the desired toeing out motion of the plurality of blades <NUM>.

In an embodiment as shown in <FIG>, a normal plane N of the offset pivots generated by the cam <NUM> and cam follower <NUM> is angled relative to the top plane of the ring frame <NUM>, represented by the dashed line, by between <NUM>°-<NUM>°. Thus when the blades <NUM> are closed the transverse axis of the arm piece <NUM> is angled. As shown in <FIG>, this angle causes the distal tip of the blade <NUM> to sweep in a downward direction <NUM> as the blade <NUM> opens. This downward sweep of the arm piece <NUM> compensates for the shortening of the effective length of the blade <NUM> due to the upward arc of the toeing blade <NUM> causing the tip of the opening blade <NUM> to remain in the same plane of the distal tips in the closed first position. This action prevents the opening blade <NUM> from lifting off the vertebral body as the blade <NUM> is toed out, which allows the surgeon to actuate the toeing out motion of the blade <NUM> without soft tissue slipping under the blade tip.

As shown in <FIG>, the tissue retractor <NUM> may further include a toe angle adjuster <NUM>. The toe angle adjuster <NUM> adjusts the initial tilt angle of the blade <NUM> in the first position. As shown in <FIG> and <FIG>, an embodiment of the toe angle adjuster <NUM> includes an adjustment knob <NUM>, a bias spring <NUM>, a set screw <NUM>, a plate <NUM>, an anchor stub <NUM>, a set screw slot <NUM>, an axle slot <NUM>, and an adjustment track <NUM>. In this exemplary embodiment, the plate <NUM> is disposed within the arm piece <NUM> such that the top surface of the plate <NUM> is in contact with the arm piece <NUM> and the second pivot post <NUM> opposes the first pivot post <NUM> in a similar position as the embodiment shown in <FIG>. When properly fit, an adjustment post 265a protrudes through adjustment track <NUM> and extends beyond the plane of the arm piece <NUM> surface. An axle 265b fits into axle slot <NUM> and provides the rotational axis for plate <NUM>. The adjustment knob <NUM> is fit such that the set screw slot <NUM> is aligned with a central bore 261a, the protruding adjustment post 265a is housed within the displacement track 261b, and the anchor stub <NUM> is housed in a corresponding anchor notch 261c.

Adjustment knob <NUM> is configured to linearly displace the adjustment post 265a within the length of adjustment track <NUM>. As shown in <FIG>, the length of the adjustment track <NUM> corresponds to the displacement between the two ends of the displacement track 261b. In the example embodiment shown in <FIG>, the second pivot post <NUM> and the cam follower <NUM> are disposed on the bottom surface of plate <NUM>, thus displacement of the adjustment post 265a along the adjustment track <NUM> displaces the cam follower <NUM> with respect to the cam <NUM>. The transferred motion causes rotational motion at the pivot points <NUM> and subsequent rotation of the arm piece <NUM> and toeing out of the blade <NUM> while in the first position. The depiction in <FIG> is merely for illustrative purposes and is not drawn to scale.

The anchor stub <NUM> fits into one of the plurality of anchor notches 261c to immobilize the adjustment knob <NUM> to a pre-calibrated position thus maintaining the desired initial toe angle. As illustrated in <FIG> the adjustment knob <NUM> may have calibrated demarcations corresponding to each of the anchor notches 261c. The demarcations may be calibrated to provide initial toe angle adjustment from about <NUM>° to about <NUM>°, preferably from about <NUM>° to about <NUM>°, and most preferably from about <NUM>° to about <NUM>°. The demarcations can be incremented at about <NUM>° increments to about <NUM>° increments.

As shown in <FIG>, the set screw <NUM> has a rim 263a preventing the screw from immobilizing the adjustment knob <NUM>. Bias spring <NUM> is disposed about the set screw <NUM> and between the top surface of the adjustment knob <NUM> and the set screw head. The bias spring <NUM> provides sufficient normal force on the adjustment knob <NUM> such that the anchor notch 261c housing anchor stub <NUM> can maintain the selected initial toe angle. The bias spring <NUM> further allows the surgeon to pull up on the adjustment knob <NUM> to remove anchor stub <NUM> from anchor notch 261c and rotate the adjustment knob <NUM> to another position.

Now referring to <FIG>, a blade <NUM> having a blade mounting and adjustment mechanism <NUM> allowing for connection of the blade <NUM> to a lever <NUM> and adjustment of the depth of the blade <NUM> of the tissue retractor <NUM> is provided.

The blade <NUM> may be used with a retractor <NUM> having a housing <NUM> adapted to connect with the adjustment mechanism <NUM> of the blade <NUM>. It should be appreciated that any retractor, including the retractors disclosed herein may be adapted to include the housing <NUM>. The adjustment mechanism <NUM> includes a threaded portion <NUM> formed on the blade <NUM>. The adjustment mechanism <NUM> further includes an adjustment screw <NUM>, at least a portion of the adjustment screw being threaded. The adjustment screw <NUM> connects the blade <NUM> to the lever <NUM> by means of the housing <NUM>. The threaded portion <NUM> of the blade <NUM> is mechanically coupled to the threaded portion of the adjustment screw <NUM> wherein rotation of the adjustment screw <NUM> displaces the blade <NUM> in a vertical arrangement thereby allowing for adjustment of the depth of the blade <NUM>.

In this embodiment, the adjustment mechanism <NUM> is mounted to the blade <NUM> of the retractor. Furthermore, a spring loaded locking lever <NUM> is connected to the threaded portion of the adjustment screw <NUM>, the locking lever <NUM> movable with the adjustment screw <NUM> during depth adjustment.

Accordingly, the blades <NUM> may be adjusted in depth so as to eliminate the use of shims used to increase the overall length of a typical blade. Further, the depth adjustment mechanism is disposed on the blade <NUM> itself and integrates with the blade <NUM> itself thereby minimizing the size of the retractor so the surgeon has the maximum amount of visualization when taking photos or performing a procedure.

An important factor in blade <NUM> height adjustment is the size of the mount. As used herein, the mount refers to the structure for supporting the blade <NUM> to the retractor. The adjustment mechanism <NUM> allows for both adjustment and attachment of the blade <NUM> to the lever <NUM>, while maintaining a smaller physical dimension relative to currently known mounts. Minimizing the size of the mount provides the surgeon with a greater field of view and camera angle when taking photos or performing a procedure. Having a blade <NUM> with an adjustment mechanism described herein minimizes the size of the blade mount by integrating blade locking and height adjustment features in one package.

Once locked, the rotating adjustment screw <NUM> allows for continuous blade height adjustment. <FIG> illustrate several embodiments of a retractor <NUM> having an adjustment mechanism <NUM>. Although the disclosed embodiments illustrate a retractor <NUM> having two handles <NUM> squeezable to facilitate expansion of the blades <NUM>, other embodiments such as the ring embodiment may also include the adjustment mechanism <NUM> described herein.

The retractor assembly <NUM> includes at least one lever <NUM> having a distal end <NUM>. The distal end <NUM> is adapted to connect to the blade <NUM>. The levers <NUM> are generally elongated and are adapted to connect with the blades <NUM> at a housing <NUM>. The blades <NUM> connect and lock to the distal end <NUM> of the lever <NUM> by means of the locking lever <NUM>. The levers <NUM> further include handles <NUM> with locking mechanisms <NUM>, <NUM>. The retractor <NUM> further includes mounting members <NUM>, <NUM> adapted to mount to at least one surgical table arm <NUM>. In the present embodiment, the retractor <NUM> is shown having a posterior arm <NUM> providing for connection to a third posterior blade. The posterior blade arm <NUM> also includes the adjustment mechanism <NUM>.

The blade <NUM> includes a distal end <NUM> and a corresponding proximal end <NUM>. A curved arm <NUM> extends outwardly from the proximal end of the blade <NUM> and is generally orthogonal to the axial length of the blade <NUM>. The curved arm <NUM> is adapted to hold the adjustment mechanism <NUM> and to place the blades <NUM> in a position to form a generally cylindrical surgical corridor when pressed together in a first position as shown in <FIG>. The adjustment mechanism <NUM> is partially shown in <FIG> and fully illustrated in <FIG> and <FIG>. The adjustment mechanism <NUM> includes a partially open bore <NUM> at the distal end of the arm <NUM>. The bore <NUM> includes a threaded portion <NUM> along at least a portion of the interior surface of the bore <NUM>. The adjustment portion <NUM> further includes an outer surface <NUM> adapted to form a generally smooth outer surface with the lever <NUM>. Indentations <NUM> are provided to connect with the distal end of the lever <NUM>.

The adjustment mechanism <NUM> includes the adjustment screw <NUM>. The adjustment screw <NUM> includes a threaded portion <NUM> and a head <NUM>. The threaded portion <NUM> covers at least a portion of the outer surface <NUM> of the adjustment screw <NUM>. The threaded portion <NUM> is adapted to connect with the threaded portion <NUM> of the bore <NUM>. An upper lip <NUM> may be further provided at an upper portion of the bore <NUM>. The lip <NUM> may be slightly crimped to prevent the adjustment screw from dislodging. Alternatively or in addition to, a harness <NUM> is provided to prevent dislodgment of the adjustment screw <NUM> during adjustment. The harness <NUM> includes an aperture to accept the set screw <NUM>. The set screw <NUM> is adapted to secure to the aperture <NUM> of the arm <NUM> of the blade <NUM>. The harness <NUM> includes a U-shaped portion <NUM> adapted to connect to the adjustment screw <NUM>.

The distal portion of the lever <NUM> is adapted to hold the locking lever <NUM>. The locking lever <NUM> includes a notch <NUM> adapted to connect to the threaded portion <NUM> of the adjustment screw <NUM>. The locking lever <NUM> further includes an aperture <NUM> adapted to connect to a pin <NUM>. The pin <NUM> allows for the locking lever <NUM> to pivot and thus release from the adjustment screw <NUM>. The locking lever <NUM> includes a handle portion <NUM> allowing the user to rotate the locking lever <NUM> about the pivot pin <NUM>. Rotation of the locking lever <NUM> results in unlocking of the adjustment mechanism <NUM> and thus release of the blade <NUM>.

The adjustment mechanism <NUM> is mounted to the blade <NUM> and directly locks to the locking lever <NUM>. Once the locking lever <NUM> is released, the entire blade <NUM> is also accordingly released and thus can be removed. The locking lever <NUM> is mounted to the lever <NUM> by the pivot pin <NUM> that allows the top of the locking lever <NUM> to act against a spring and thus swing open. The threaded portion <NUM> of the adjustment screw <NUM> slides down a ramped portion <NUM> on the locking lever <NUM> causing the lever <NUM> to swing open as the blade <NUM> is inserted into the lever <NUM>. The threaded portion <NUM> of the adjustment screw <NUM> has defined edges that create a cylindrical shape which engages the notch <NUM> of the locking lever <NUM>. The notch <NUM> includes a plurality of generally planar surfaces arranged to securely accept the threaded portion <NUM> of the adjustment screw. The threaded portion <NUM> of the adjustment screw <NUM> is captured by the indentation <NUM> and held in a closed position by a spring that acts behind the locking lever <NUM> and is contained within the lever <NUM>. When the locking lever <NUM> is closed around the threaded portion <NUM> of the adjustment screw <NUM>, the adjustment screw <NUM> is free to rotate and thus adjust the height or depth of the blade <NUM>.

Depth adjustment of the blade is accomplished by rotation adjustment screw <NUM>. Specifically, rotation head <NUM> actuates rotation of the adjustment screw <NUM>. In the present embodiment, a wrench is used to turn the adjustment screw at the head <NUM>. In other embodiments, a nut or other handle connected to the adjustment screw may be utilized to rotate the adjustment screw <NUM>.

The threaded portion <NUM> of the adjustment screw <NUM> mates with a threaded portion <NUM> of the bore <NUM>. As the adjustment screw <NUM> is rotated, the blade <NUM> can be raised or lowered as the threaded portion <NUM> of the adjustment screw <NUM> moves up and down in the bore <NUM>. The threaded portion <NUM> of the adjustment screw <NUM> mates with the threaded portion <NUM> of the bore <NUM>. Rotation of the adjustment screw <NUM> results in a downward or upward motion of the blade <NUM>. The arm <NUM> of the blade <NUM> accordingly is displaced as the adjustment screw is rotated.

<FIG> illustrate rotation and height adjustment of the blade <NUM>. <FIG> illustrates the retractor <NUM> having the blade <NUM> before any adjustment. A bone surface <NUM> is provided at the distal end <NUM> of the blade <NUM>. As illustrated in <FIG>, before a height adjustment of the blade <NUM>, the distal end <NUM> is spaced apart from a bone surface <NUM>. The gap ΔX between the bone surface <NUM> and the distal end <NUM> of the blade <NUM> may result in soft tissue encroaching into the surgical site <NUM>. In the present embodiment, ΔX ranges between <NUM>-<NUM> millimeters. However, in other embodiments, ΔX may range up to <NUM> millimeters. <FIG> illustrates the blade <NUM> after it has been adjusted allowing the distal end <NUM> of the blade <NUM> to contact the bone <NUM>. This adjustment thereby prevents encroachment of soft tissue into the surgical site <NUM>.

In the present embodiment, a third posterior blade arm <NUM> is also provided. The arm <NUM> may also be adjusted in a forward and rearward direction by means of the adjustment screw <NUM>. Rotation of the adjustment screw <NUM> results in forward and rearward motion of the arm <NUM>. In the present embodiment, the adjustment screw <NUM> is adjusted with a hexagonal wrench. In other embodiments a handle or other rotation nut may be provided for adjustment. The blade connected to the posterior blade arm <NUM> is typically the blade that is anchored to the vertebrae or the annulus of the disc/the other wall of the disc itself.

The retractor <NUM> may be further configured to automatically perform a toe-out motion when the handles <NUM> are squeezed together. With reference now to <FIG>, each lever <NUM> includes at least one cam follower <NUM> mounted thereto. In the present embodiment, the lever <NUM> includes two cam followers 455a, 455b. The cam follower 455a is mounted to the arm <NUM> within the aperture <NUM>. The cam follower 455a is mounted by means of a post <NUM> connected to the lever <NUM>. The post <NUM> includes a threaded portion <NUM> adapted to secure to a lower portion of the lever <NUM>. The post <NUM> extends through the lower portion of the lever <NUM> and connects directly with the cam follower 455a.

The cam follower 455b connects to the lever <NUM> by means of a plate <NUM>. The plate <NUM> is mounted to the arm <NUM> by a post <NUM>. The post <NUM> includes a threaded portion <NUM> adapted to secure to an upper portion of the lever <NUM>. The post <NUM> extends through the upper portion of the lever <NUM> and connects directly with the plate <NUM>. The plate <NUM> includes a post (not shown) extending orthogonally from a lower surface <NUM>. The post is adapted to connect with and secure the cam follower 455b to the plate <NUM>.

Corresponding cams 451a, 451b include curved inner cam surfaces 453a, 453b adapted to operatively connect with respective cam followers 455a, 455b. The cams 451a, 451b are fixedly connected to the flange <NUM> within the apertures 439a, 439b. In this embodiment, the cams 451a, 451b and corresponding apertures 439a, 439b are offset. The cam followers 455a, 455b rest within the respective cams 451a, 451b and are free to pivot and rotate within the cams 451a, 451b when the handles <NUM> are squeezed together. When the handles <NUM> are squeezed together, the lever <NUM> is free to pivot about the cams 451a, 451b resulting in independent pivot action of the blade <NUM> (mounted to the lever <NUM>) to cause the distal end of the blade to project out radially with respect to the proximal end of the blade.

In this embodiment, the cam followers 455a, 455b are generally spherical elements having a rounded outer surface. Correspondingly, the cam surfaces 453a, 453b have a concave generally spherical surface. It should be appreciated that other geometries of both the cam followers 455a, 455b and the cam surfaces 453a, 453b may include varying geometry to accommodate the toe-out requirements of the blade <NUM>.

The blades <NUM> in a first position form a cylindrical surgical corridor, which may be used with other medical instruments such as, for example, a dilator. In the first position, the blades <NUM> may be inserted over the dilator. As the levers <NUM> are actuated, the levers <NUM> will simultaneously be urged together and rotate in a multi-plane motion causing the top and bottom sides of the jaws to follow separate arc lengths providing simultaneous opening and providing toeing action to the plurality of blades <NUM>. Expansion of the plurality of blades <NUM> will result in a toe angle in a second position (partially open view shown in <FIG>). The offset length between the cams <NUM> determines the opening angle and toe angle. The amount of tilt generated is a sinusoidal relation to the opening angle which increases in gain as the opening angle increases.

The blades <NUM> are attached to the distal ends of the levers <NUM>. In other embodiments, only one blade <NUM>. The blades <NUM> may be attached by welding or may be cast as a continuous extension from the lever. In other embodiments not shown, the blades <NUM> are detachable and have tangs disposed at the proximal end of each blade <NUM>. The blade tangs fit into corresponding recess disposed at the distal end of each lever.

The curved portion <NUM> is adapted to be inserted through the lever <NUM>. It is inserted through an aperture with a larger dimension thus allowing the curved member <NUM> tolerance within the aperture during toe-out. The radius of curvature of the curved arm <NUM> corresponds to the radius of the pivot of the lever <NUM>. The release mechanism <NUM> connected to the handle <NUM> communicates with the curved portion <NUM>. As the release member <NUM> is actuated, the curved portion is disengaged. Actuation of the release mechanism <NUM> results in release of the locking member <NUM>.

Claim 1:
A tissue retractor (<NUM>) comprising at least two blades (<NUM>), the at least two blades forming a surgical corridor, the tissue retractor comprising:
a first lever (<NUM>) and a second lever (<NUM>);
a frame (<NUM>) having a first cam (151a, 151b) and a second cam (151a, 151b), each cam being on a respective side of the frame, each cam being coupled to a respective lever (<NUM>, <NUM>);
a cam follower (<NUM>) operatively connected to a first of the two blades, the cam follower movable with respect to the frame, said tissue retractor being characterized in that
the blades (<NUM>) are adapted to be opened and closed relative to each other by squeezing the first lever (<NUM>) and second lever (<NUM>) towards each other;
wherein the cam follower is adapted to follow one of the first and second cams so as to cause a distal end of the first blade to toe out as a proximal end of the first blade is moved away from a proximal end of the other blade during actuation of the retractor, wherein, as the proximal ends of the first lever and second lever are squeezed together, the distal ends of the levers will simultaneously spread apart and rotate in a multi-plane motion causing the top and bottom sides of the levers to follow separate arc lengths and provide simultaneous opening and toeing action to the plurality of blades, wherein the first cam and the second cam each include a cam surface (<NUM>) having an arcuate path on a plane generally orthogonal to a diameter of the surgical corridor.