The present invention generally relates to apparatus and methods for tissue separation, and more particularly, to apparatus and methods for using an expanding retractor with successively larger dilator elements.
A common technique currently employed is passing the tip of a K-wire through tissues to the target location—then passing over the wire a succession of tubes of increasing diameter until reaching the optimal bore size. The drawback of this procedure is the ever increasing frictional trauma imposed on the tissue being separated. An additional shortcoming of the ‘tube’ system is that the final cross sectional shape is round.
In certain tissue environments, for instance when the target is the intervertebral disc space, approached from any angle, the above technique is not easily applicable as contiguous vital structures like nerves or blood vessels may be damaged in the process.
There is a compelling need for an improved method and apparatus for tissue separation, particular in spinal surgery.
One aspect of the present invention is an apparatus for tissue separation, comprising a hollow retractor expandable in at least one dimension, the retractor having upper and lower guide surface portions for contacting respective upper and lower tissue surfaces; a first dilator having a distal portion configured to fit inside the upper and lower guide surface portions of the retractor so as to expand a distance between the upper and lower guide surface portions of the retractor and thereby separate the upper and lower tissue surfaces by a first distance; and a second dilator having a distal portion configured to fit inside the upper and lower guide surface portions of the retractor so as to expand a distance between the upper and lower guide surface portions of the retractor and thereby render the upper and lower tissue surfaces being separated by a second distance, the second distance greater than the first distance.
A further aspect of the present invention is a method of tissue separation, comprising inserting a retractor into a tissue, the retractor having upper and lower guide surface portions that contact respective upper and lower tissue surfaces, the retractor expandable in at least one dimension so that a distance between the upper and lower guide surface portions is expandable; inserting a first dilator inside the retractor such that at least some of a length of the first dilator is placed between the upper and lower guide surface portions so as to increase a distance between the upper and lower guide surface portions and effectuate separation of the tissue by a first amount in at least one dimension, the first dilator comprising an elongated body; expanding the retractor in the at least one dimension by successively inserting a second dilator of greater size in the at least one dimension inside the retractor, the inserting performed such that at least some of a length of the second dilator is placed between the upper and lower guide surface portions so as to further increase the distance between the upper and lower guide surface portions thereby effectuating further separation of the tissue, the second dilator also comprising an elongated body.
A still further aspect of the present invention is a method of tissue separation, comprising inserting a retractor into a tissue, the retractor having upper and lower guide surface portions that contact respective upper and lower tissue surfaces, the retractor expandable in at least one dimension so that a distance between the upper and lower guide surface portions is expandable; inserting a first dilator inside the retractor such that at least some of a length of the first dilator is placed between the upper and lower guide surface portions so as to increase a distance between the upper and lower guide surface portions and effectuate separation of the tissue by a first distance, the first dilator comprising an elongated body; expanding the retractor in at least one dimension by inserting a second dilator of greater size in the at least one dimension inside the retractor without removing the first dilator, the inserting performed such that at least some of a length of the second dilator is placed between the upper and lower guide surface portions so as to further increase the distance between the upper and lower guide surface portions thereby effectuating further separation of the tissue by a greater distance.
A yet still further aspect of the present invention is a method of sizing a limit of tissue separation, comprising (a) assessing a quality of tissue being separated by (i) inserting a retractor into a tissue, the retractor having upper and lower guide surface portions that contact respective upper and lower tissue surfaces, the retractor expandable in at least one dimension so that a distance between the upper and lower guide surface portions is expandable, and by (ii) inserting a first dilator inside the retractor such that at least some of a length of the first dilator is placed between the upper and lower guide surface portions so as to increase a distance between the upper and lower guide surface portions and effectuate separation of the tissue by a first distance; and (b) sizing/assessing a limit to which the tissue is separable by expanding the retractor in at least one dimension by successively inserting a further dilator of successively greater size in the at least one dimension inside the retractor, the inserting performed such that at least some of a length of each of the further dilators is placed between the upper and lower guide surface portions so as to further increase the distance between the upper and lower guide surface portions thereby effectuating further separation of the tissue in successively greater amounts.
A still further aspect of the present invention is an apparatus for tissue separation, comprising a hollow retractor expandable in at least one dimension, the retractor having upper and lower guide surface portions for contacting respective upper and lower tissue surfaces; a dilator having a distal portion configured to fit inside the upper and lower guide surface portions of the retractor so as to expand a distance between the upper and lower guide surface portions of the retractor and thereby separate the upper and lower tissue surfaces by a first distance.
A yet still further aspect of the present invention is a method of using a retractor for an insertion of an element into a human body, comprising inserting a retractor into a tissue, the retractor having upper and lower guide surface portions that contact respective upper and lower tissue surfaces, the retractor expandable in at least one dimension so that a distance between the upper and lower guide surface portions is expandable; inserting a dilator inside the retractor such that at least some of a length of the first dilator is placed between the upper and lower guide surface portions so as to increase a distance between the upper and lower guide surface portions and effectuate separation of the tissue by a first amount in at least one dimension; forming a passageway inside the retractor by removing the dilator; and inserting an implant through the passageway and into the human body.
Another aspect of the present invention is a method of using a retractor for an insertion of an element into a human body, comprising inserting a retractor into a tissue, the retractor having upper and lower guide surface portions that contact respective upper and lower tissue surfaces, the retractor expandable in at least one dimension so that a distance between the upper and lower guide surface portions is expandable; inserting a dilator inside the retractor such that at least some of a length of the first dilator is placed between the upper and lower guide surface portions so as to increase a distance between the upper and lower guide surface portions and effectuate separation of the tissue by a first amount in at least one dimension; forming a passageway inside the retractor by removing the dilator; and inserting a surgical tool through the passageway and into the human body.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, descriptions and claims.
Various embodiments are herein described, by way of example only, with reference to the accompanying drawings, wherein:
a is an isometric view of a curved cross-section for upper of lower guide surface portions of a retractor, in accordance with one embodiment of the present invention; and
b is an isometric view of a flat cross-section for upper of lower guide surface portions of a retractor, in accordance with one embodiment of the present invention.
The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
The present invention generally provides a method and apparatus for tissue separation. The tissue separation may be necessary as part of a surgical procedure or operation, for example during a discectomy, for example where it is necessary to increase the gap between two vertebrae. A retractor, expandable in at least one dimension, may be inserted into the area of the tissue, for example between discs of a spine. The retractor may have a distal guide surface or surfaces (meaning distal in relation to the surgeon which in this case may mean inside the subject's spine) including upper and lower guide surface portions that may make contact with respective upper and lower tissue surfaces. In a preferred embodiment, after the retractor is in place, one may insert into the retractor a first dilator having a distal portion that can forcibly fit inside the upper and lower guide surface portions of the retractor so as to expand the distance between the upper and lower guide surface portions of the retractor and thereby separate the upper and lower tissue surfaces by a first distance. In one preferred embodiment, the first dilator is removed from the retractor and a further dilator that is larger in the dimension that the tissue dilator is expanded, for example in height, is then inserted into the retractor. In a second preferred embodiment, the first dilator remains in the retractor while a further second dilator having a larger height in the dimension that the retractor expands in can be inserted forcibly inside the retractor. This may expand the distance between the upper and lower guide surface portions of the retractor and thereby render the upper and lower tissue surfaces being separated by a second distance greater than the first distance. Passage of the dilators may optionally be a tissue sampling procedure as well as a sizing dilation step. Reaching the final dilation may provide information regarding the size of the disc space, consequent preparatory tools (or other tools) as well as the size of the implant that is to be surgically inserted, for example between the vertebrae. The upper and lower guide surface portions of the retractor may, in some preferred embodiments, effectively act like a shoe horn, displacing the adjacent tissue as successive dilators are advanced between the upper and lower guide surface portions while greatly reducing frictional trauma to the tissue. The retractor depicted herein may be square in its cross-sectional shape, but it can assume any other shape, regular or irregular, symmetric or asymmetric. The retractor can be used for tissue separation anywhere in the body of humans and non-humans. For the sake of example, the embodiment presented is one of separating tissues on the way to and within the intervertebral disc. In a typical application, corresponding to a method according to the present invention, a k-wire is inserted within the disc space and its position is verified by a C-arm fluoroscopy. The retractor is passed over the k-wire with the thinner distal end of the retractor penetrating the annulus and its position determined by fluoroscopy. The penetration point through the annulus is at the discretion of the user, all around the annulus, 360 degrees. The retractor may be held secure by a fixator device attached to the operating table—or may be fixed to vertebral screws (or other devices such as spinous process fixation devices)—or may be held manually by the user—or by other means. Once the retractor has been positioned within the tissue space (disc space in the case of spinal surgery), dilators may be sequentially introduced into it to enlarge at least part of its length the opening and allow passage of instruments, implants and/or materials (such as fusion inducing materials) inwardly and/or passage outwardly (i.e. disc tissue). The proximal portion of the retractor arms typically remains out of the body of the patient/subject and its height may remain constant. In the case of disc space procedures, this height typically reaches about 14 mm but may differ according to the specific application of the device.
In contrast to prior art retractors, in which successive hollow tubes may be placed on a K-wire in order to separate tissue, thereby causing trauma to the tissue as each successive tube is dragged along the tissue in order to reach its place, the method and apparatus of the present invention may be used to separate the affected tissue without causing repeated trauma. Successive dilators may be inserted through a hollow retractor expandable in at least one dimension. In this way, only the retractor need contact the tissue. The dilators need not contact the tissue. By inserting successive dilators, the tissue to be separated may be sized without having to successively pass tubes past the tissue. There may be no relative motion causing friction between the retractor and the tissue with which it comes in contact. The progressive increase in one or more dimensions from within the inside of the retractor eliminates the successive passage of traumatizing tubes on the outside of the retractor. In further contrast to the prior art, in which the cross-section of the successive tubes may be circular, the retractor may have a generally square cross-section. In contrast to the prior art, passage of the dilators increasing in size, may offer vital information to the user imparted by tactility, i.e. assessment of disc tissue quality whether dry and fibrotic or plump and soft. It also allows the user to feel the limits of the stretch that can be applied to the surrounding soft tissues of the motion segment and so avoid excessive dilation and endplate damage and/or soft tissue damage (tearing of muscle or ligamentous tissue such as the anterior longitudinal ligament).
The principles and operation of an apparatus and method for a retractor tool with successive dilators according to the present invention may be better understood with reference to the drawings and the accompanying description.
As shown from
The tissue separator 10 may also include a second dilator 40 having a distal portion configured to fit inside the upper and lower guide surface portions of the retractor so as to expand a distance between the upper and lower guide surface portions of the retractor and thereby render the upper and lower tissue surfaces being separated by a second distance, the second distance greater than the first distance. The second dilator may be larger than the first dilator in at least one dimension, for example in the height dimension, which in the context of spinal surgery, can be called the cephalad-caudad dimension. The dilators may be made of any biocompatible material(s), including but not limited to metallic material(s), polymeric material(s) or other or a combination of such materials.
In one preferred embodiment, the retractor 20 is defomable in at least a distal portion of a length of the retractor 20 to accommodate dilators that are successively larger in at least one dimension. For example, in this regard, the distal portion may be the last 10%, or in other preferred embodiments, at least 50% of the length of the retractor, or in some preferred embodiments, at least the upper and lower guide surface portions of the retractor.
In any case, the length of the retractor arm that deforms does not necessarily have to be symmetric to the other retractor arm. For example, one retractor may be fixed and another retractor may be the component that performs all the retraction. Optionally one retractor may deform the distal part to a certain amount while the other retractor deforms to a different amount (either more or less than the first retractor.
The retractor 20, or at least the upper and lower guide surface portions, may be deformable as a result of being made from plastic and/or superelastic material. For example, the upper and lower guide surface portions may be formed from Nitinol superelastic materials, allowing them to smoothly deform to accommodate successively wider dilators advancing between the upper and lower guide surface elements, and then return to their original form. In other embodiments, the guide surface portions may be plastically deformed during insertion of the dilators.
In a second preferred embodiment shown in
As shown in
First dilator 30 may comprise a core element 32 (sometimes called a first core element since it is the core element of the first dilator 30) that has at least a top surface 34 and a bottom surface 35, and may comprise a support element 36 (also sometimes referred to as a first support element 46 since it is the support element for the first dilator 30) that may have at least one side wall 36a, and in a preferred embodiment two (left and right) side walls 36a, 36b. Similarly, second dilator 40 may comprise a core element 42 (sometimes called a second core element since it is the core element of the second dilator 40) that has at least a top surface 44 and a bottom surface 45, and may comprise a support element 46 (also sometimes referred to as a second support element 46 since it is the support element for the second dilator 40) that may have at least one side wall 46a, and in a preferred embodiment two (left and right) side walls 46a, 46b.
As can be appreciated from
In some preferred embodiments, the support element may be removable from the retractor without the core element having to be removed.
First dilator 30 may have a first core element and a first support element of a first size and second dilator 40 may have a second core element and a second support element of a second size. For example, first core element 32 and first support element 36 may both be 7 mm in height (as measured by the distance between retractor arms 22a, 24a) whereas second core element 42 and second support element 46 may be 9 mm in height (as measured by the distance between retractor arms 22a, 24a). Typically, for any dilator its core element and its support element may be equal in height, although there could be preferred embodiments in which the core element of a dilator is slightly larger or slightly smaller (for example plus or minus 1% or 2% or 4% or 5% or 7% or 10% or 15% or more) than the support element (i.e. side walls) of that dilator.
It is noted that the length of any of the dilators (i.e. 30, 40) in the method and apparatus of the present invention may be greater than, equal to, or less than the length of the retractor 20. Furthermore, any of the dilators may be positioned relative to the retractor so that the dilator extends distally beyond the retractor. The purpose of having a dilator extend beyond the retractor may be so that (a) the dilator may reach/extend beyond the retractor tips and pierce/dilate/expand/manipulate tissue that is exterior to the retractor tips, and/or (b) the dilation may be very gradual (i.e. dilator tip may have a small angle).
The apparatus for tissue separation described in
The apparatus may include a mechanism for maintaining the hollow retractor in a retracted position with a set distance between the upper and lower guide surface portions when the dilator is removed before being replaced with a dilator of a different size. In some preferred embodiments, for example
In another preferred embodiment, the mechanism for maintaining the retractor in a retracted position may be a hinge mechanism (for example hinge mechanism 250 as seen in
As can be seen, the retractor of the present invention (20, 120, 220, 320) is expandable in a height dimension. In some preferred embodiments, the retractor is expandable in a height dimension and in a width dimension. This is necessary in certain surgical environments. Enlargement of the opening may vary taking into consideration the point of penetration: in the case of PLIF or TLIF procedures, the opening preferably gains only in height (in the sagittal plane, (i.e., the cephalad-caudad dimension)) as sideways/lateral widening of the entrance may compromise the adjacent nerve root and/or dura. The width of the retractor may be fixed and may not change all along the instrument. If the penetration is through the anterior annulus as in ALIF (or through soft tissue), widening may be concomitantly done sideways as well. If the widening is in more than one direction, the widening may be simultaneous in the plurality of directions or each direction widened in sequence.
As seen in
In any of the embodiments of the method or apparatus of the present invention, in expanding the distance between the upper and lower surface guide portions, the upper and lower surface guide portions may be moved symmetrically or asymmetrically and may or may not have an equal share in performing the retraction. First of all, the length of one retractor arm that deforms or moves against the tissue may differ from the length of the other retractor arm that deforms or moves against the tissue. For example, the upper retractor arm's upper surface guide portion may have more of its length deform or move than the lower retractor arm's lower surface guide portion. Second, the quantity of the retraction movement may be more or less for one retractor arm's surface guide portion than for another. One extreme example of this, which may appear in certain preferred embodiments, is, as shown in
In a further preferred embodiment shown in
In a still further preferred embodiment of a tissue separator 200 shown in
In a still further preferred embodiment,
As shown in
The flaps 327 may be made of any suitable material including, but not limited to, metal or metal alloys (collectively metallic material) and biocompatible plastics or other polymers.
As shown in
Method 400 may also include a step 420 of inserting a first dilator inside the retractor such that at least some of a length of the first dilator is placed between the upper and lower guide surface portions so as to increase a distance between the upper and lower guide surface portions and effectuate separation of the tissue by a first amount in at least one dimension. The first dilator may utilize any of the embodiments described for the apparatus of the present invention and may comprise an elongated body.
A further step 430 of method 400 may be expanding the retractor in the at least one dimension by inserting a second dilator of greater size in the at least one dimension inside the retractor, the inserting performed such that at least some of a length of the second dilator is placed between the upper and lower guide surface portions so as to further increase the distance between the upper and lower guide surface portions thereby effectuating further separation of the tissue by a greater distance. The second dilator may utilize any of the embodiments described for the apparatus of the present invention and may comprise an elongated body. In a preferred embodiment of method 400, the first and further dilators may be inserted into the retractor without the first and further dilators contacting the upper and lower tissue surfaces. The method 400 also may involve effectuating still further dilation by successively inserting one or more further dilators (beyond the second dilator) between the upper and lower guide surface portions so as to further increase the distance between the upper and lower guide surface portions by successively greater amounts. The number of such further dilators may be one, at least one, two, at least two, three, at least three, four, at least four, five, at least five, or a higher number, as needed. In some preferred embodiments of method 400 the expanding the retractor further includes successively removing a dilator before successively inserting the second dilator (or the further dilator).
Method 400 may utilize any of the embodiments of tissue separator 10, 100, 200, 300. For example, in one preferred embodiment, inserting the retractor into a tissue involves inserting opposing upper and lower U-shaped walls into the tissue. In another example, the second dilator (and any further dilator) may comprise a core element and a support element, and the expanding the retractor may comprise first replacing the core element of a first size of the first dilator with a core element of a second size of the second dilator, the second size core element larger than the first size core element, and then afterwards replacing the support element of a first size of the first dilator with a support element of a second size of the second dilator, the second size support element larger than the first size support element. In a further example, each dilator (and any further dilator) may comprise a core element and a support clement, and wherein the expanding the retractor comprises removing the core element of a particular dilator (for example the first dilator) before removing the support element of that particular dilator (for example the first dilator). In a still further example, the first and second dilators each comprise a core element and a support element, and wherein the expanding the retractor comprises inserting a core element of the second dilator before removing the support element of the first dilator.
In another example, inserting the core element of the second dilator may be preceded by removing the core element of the first dilator. In a further example, each of the first dilator and second dilator may comprise a core element and a support element, and a multiple expansion of the retractor may comprise first expanding the retractor by removing the core element of the first dilator, inserting the core element of the second dilator of a second size before removing the support element of the first dilator, removing the support element of the first dilator, inserting the support element of the second dilator, and then further expanding the retractor including by removing the core element of the second dilator and inserting a core element of a third dilator before removing the support element of the second dilator. The process between the second and third dilators may be continued similar to the process between the first and second dilators. The core element is replaced before the support element is replaced.
In still another example, the method 400 may involve using a hinge to move the upper and lower guide surface portions to an initial distance prior to inserting the first dilator, the hinge also setting a maximum retraction of the upper and lower guide surface portions for the first dilator. The method 400 may also involve using the hinge to move the upper and lower guide surface portions to an initial distance prior to inserting the second dilator, the hinge also setting a maximum retraction of the upper and lower guide surface portions for the second dilator.
In a further example, method 400 may have a further step of configuring the upper and lower guide surface portions to converge at distal tips at an initial position and to be expanded by insertion of the first and second dilators.
In some preferred embodiments, method 400 may also comprise a step wherein the first and second dilators each move flaps at the upper and lower guide surface portions of the retractor.
In other preferred embodiments of the method of the present invention other than method 400, the insertion of the second. dilator (or further dilators) may occur without removal of the previously inserted first dilator (or second or further dilators). For example, in such a method of tissue separation, a first step may involve inserting a retractor into a tissue, the retractor having upper and lower guide surface portions that contact respective upper and lower tissue surfaces, the retractor expandable in at least one dimension so that a distance between the upper and lower guide surface portions is expandable.
A second step may involve inserting a first dilator inside the retractor such that at least some of a length of the first dilator is placed between the upper and lower guide surface portions so as to increase a distance between the upper and lower guide surface portions and effectuate separation of the tissue by a first distance. The first dilator may comprise an elongated body.
A third step may be expanding the retractor in at least one dimension by inserting a second dilator of greater size in the at least one dimension inside the retractor without removing previously inserted first dilator. This may be accomplished in a variety of ways, for example by using dilators whose outer walls are flexible and hollow. The inserting may be performed such that at least some of a length of the second dilator is placed between the upper and lower guide surface portions so as to further increase the distance between the upper and lower guide surface portions thereby effectuating further separation of the tissue by a greater distance. The second dilator may also comprise an elongated body.
In a still another preferred embodiment of a method of the present invention, the method of sizing a limit of tissue separation may comprise a first step of (a) assessing a quality of tissue being separated by
(i) inserting a retractor into a tissue, the retractor having upper and lower guide surface portions that contact respective upper and lower tissue surfaces, the retractor expandable in at least one dimension so that a distance between the upper and lower guide surface portions is expandable, and by
(ii) inserting a first dilator inside the retractor such that at least some of a length of the first dilator is placed between the upper and lower guide surface portions so as to increase a distance between the upper and lower guide surface portions and effectuate separation of the tissue by a first distance.
A second step may involve (b) sizing/assessing a limit to which the tissue is separable by expanding the retractor in at least one dimension by successively inserting a further dilator of successively greater size in the at least one dimension inside the retractor, the inserting performed such that at least some of a length of each of the further dilators is placed between the upper and lower guide surface portions so as to further increase the distance between the upper and lower guide surface portions thereby effectuating further separation of the tissue by successively greater distances. In some preferred versions, the second step includes removing a dilator before a further dilator is inserted.
The present invention may also be characterized as a method of using a retractor for an insertion of an element into a human body. This method may comprise a step of inserting a retractor into a tissue, the retractor having upper and lower guide surface portions that contact respective upper and lower tissue surfaces, the retractor expandable in at least one dimension so that a distance between the upper and lower guide surface portions is expandable. This method may also include a further step of inserting a dilator inside the retractor such that at least some of a length of the first dilator is placed between the upper and lower guide surface portions so as to increase a distance between the upper and lower guide surface portions and effectuate separation of the tissue by a first amount in at least one dimension. A further step of the method may be forming a passageway inside the retractor by removing the dilator. The method may also involve a step of inserting (i) an implant, (ii) a surgical tool or (iii) an implant and a surgical tool, through the passageway and into the human body.
In any embodiment of the present invention, the surface guide portions, for example the upper and lower surface guide portions, may have teeth/ridges/protrusions externally on the ends that may be embedded into the tissue (endplate or other) to provide at least some fixation of the retractor to the tissue. The upper and lower surface guide portions may have internally facing protrusions (stoppers) to prevent dilators or other instruments from advancing beyond the tip of the retractor.
The upper and lower guide surface portions typically conform to the surface of the tissue against which they are pressed as the dilator advances, remaining substantially parallel to each other. Optionally, the thickness of the guide portions may be variable so as to define a single or more preferably double hinge arrangement, with the distal part of the guide portion being relatively more rigid, and being forced outwards as a unit, thereby spreading the applied pressure more evenly across a relatively large area of tissue.
Where dilation is required in two perpendicular dimensions, two pairs of guide surface portions may be used, and successive dilators may increase, either simultaneously or intermittently, in both dimensions. Optionally, a single sequence of dilators may be used with each being inserted in two orientations to separately increase both height and width dimensions.
The apparatus of the present invention can be a universal tool that incorporates other inventive concepts. For example, if the apparatus is used according to the “NonLinear” concept (i.e., as a part of a system and method as described in various prior co-assigned patent applications) in which the tools and implants are deflected into circuitous trajectories, the medial wall of the retractor may be reinforced to enable curling of the multi-link structures around the distal end of the wall.
While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. Therefore, the claimed invention as recited in the claims that follow is not limited to the embodiments described herein.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB2012/053516 | 7/10/2012 | WO | 00 | 1/10/2014 |
Number | Date | Country | |
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61506102 | Jul 2011 | US |