WO2001003586A1

WO2001003586A1 - Concentrically expansible needle retractor

Info

Publication number: WO2001003586A1
Application number: PCT/IL2000/000387
Authority: WO
Inventors: David Michaeli
Original assignee: David Michaeli
Priority date: 1999-07-07
Filing date: 2000-07-04
Publication date: 2001-01-18
Also published as: IL130835A0; AU2000255620A1

Abstract

An expansible needle retractor device, includes a base arranged for positioning over an opening in a body portion; an expandable needle shaped retractor element having a longitudinal opening and an axis extending therealong, and configured for insertion through the opening so as to extend into the body portion and thus to engage body tissue, the retractor element having a first end supported in association with the base and a second, free end, spaced axially therefrom; and expansion apparatus mounted onto the base and operative to selectably expand the retractor element radially about the longitudinal axis into expanded position so as to retract body tissue engaged by the retractor element, and thereby to expose a working area within the body portion, in generally axial alignment with the opening.

Description

CONCENTRICALLY EXPANSIBLE NEEDLE RETRACTOR

FIELD OF THE INVENTION The present invention relates to apparatus and techniques for performing minimally invasive surgery.

BACKGROUND OF THE INVENTION

Minimally invasive surgical techniques are becoming increasingly widespread in many different surgical fields. An area in which such techniques would appear to be particularly relevant is neurosurgical removal of space occupying lesions.

In accordance with current methods, following initial imaging for locating a lesion, the skull is trepanned so as to remove a bone flap exposing an opening of up to 5 cm x 5 cm, after which retractors are inserted between the brain lobes and used to move and draw back the lobes in the region of the lesion, thereby exposing it for removal. After a procedure which can take many hours, the retractors are removed and the bone flap is replaced. Imaging is performed once again so as to ensure that the entire lesion has, in fact, been removed.

Among disadvantages of this known procedure are the following:

1. the localized pressure to which the retracted portions of the brain is subjected is considerable, and can cause infarction of brain tissue,

2. bleeding occurs upon insertion of the retractors,

3. due to the fact that several retractors may have to be inserted, the pressure on the brain tissue is uneven, and the lesion may not be properly exposed in a manner which facilitates easy and complete removal thereof, possibly leading to a need to perform supplementary surgery in order to remove any remaining tumor tissue, and

4. insertion of the retractors and separation of the brain lobes are performed manually; these motions are thus inherently uneven, and are liable to cause trauma to the patient. SUMMARY OF THE INVENTION

The present invention seeks to provide a concentrically expansible needle retractor device for minimally invasive surgery, and a surgical technique for employing the retractor device.

A further aim of the present invention is to render surgical procedures, including neurosurgical procedures, shorter, less traumatic, and more reliable.

There is thus provided, in accordance with a preferred embodiment of the invention, an expansible needle retractor device which includes a base arranged for positioning over an opening in a body portion; an expandable needle shaped retractor element having a longitudinal opening and an axis extending therealong, and configured for insertion through the opening so as to extend into the body portion and thus to engage body tissue, the retractor element having a first end supported in association with the base and a second, free end, spaced axially therefrom; and expansion apparatus mounted onto the base and operative to selectably expand the retractor element radially about the longitudinal axis into an expanded position so as to retract body tissue engaged by the retractor element, and thereby to expose a working area within the body portion, in generally axial alignment with the opening.

Additionally in accordance with the present invention, the retractor element is formed of a plurality of generally rigid rib members extending from the base, joined by an extendible web, which, when the retractor element is in the expanded position, is operative to resist, together with the elongate members, return of retracted body tissue to its non-retracted state.

Additionally in accordance with the present invention, the retractor element is expansible concentrically about the longitudinal axis.

Additionally in accordance with the present invention, the rib members are connected at the first end of the needle element to the expansion apparatus, and are distributed generally evenly about the longitudinal axis, thereby to expand in concentric fashion thereabout.

Additionally in accordance with the present invention, the extendible web is a flexible membrane.

Additionally in accordance with the present invention, the expansion apparatus is operative to expand the retractor element at a predetermined speed, thereby to provide retraction of body tissue at a corresponding rate, predetermined to minimize trauma to the tissue.

Additionally in accordance with the present invention, the expansion apparatus includes electrical drive apparatus.

Additionally in accordance with the present invention, there is also provided a probe mounted onto the second, free end of the retractor element.

Additionally in accordance with the present invention, the probe includes at least one of the group consisting of an imaging probe, and an electrocoagulation probe.

There is also provided, in accordance with a method of the invention, a method of minimally invasive surgery, which includes the following steps: forming an opening in the exterior of a body portion located in proximity to a tissue portion sought to be surgically removed; inserting a radially expansible needle-like retractor element through the opening, through body tissue so as to reach the tissue portion sought to be surgically removed; expanding the retractor element concentrically, thereby to cause a lateral displacement of adjacent tissue, so as to expose the tissue portion sought to be surgically removed; and removing the tissue portion sought to be surgically removed.

Additionally in accordance with the present embodiment of the invention, the method also includes the step of inserting an imaging probe in association with the retractor element, thereby to provide imaging of a selected tissue portion during insertion thereof through body tissue.

Additionally in accordance with the present embodiment of the invention, the method also includes the step of inserting an electrocoagulation probe in association with the retractor element, thereby to provide selectable cauterization of blood vessels proximate thereto during insertion thereof through body tissue.

Additionally in accordance with the present embodiment of the invention, the step of forming an opening includes forming an opening of substantially same diameter as the retractor element, once expanded.

Additionally in accordance with the present embodiment of the invention, the step of expanding includes the step of expanding the retractor element at a preselected rate.

Additionally in accordance with the present embodiment of the invention, the step of forming an opening in the exterior of a body portion located in proximity to a tissue portion sought to be surgically removed includes forming an opening in a skull of a subject, located in proximity to a space occupying lesion sought to be removed from the subject's brain; the step of inserting a radially expansible needle-like retractor element includes inserting the retractor element between brain lobes so as to reach the space occupying lesion sought to be surgically removed; and the step of expanding the retractor element includes separating brain tissue adjacent thereto, so as to expose the space occupying lesion.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood and appreciated from the following detailed description, taken in conjunction with the drawings, in which:

Fig. 1A is a side view of the concentrically expansible needle retractor device of the present invention in a contracted position;

Fig. IB is a cross-sectional view of the retractor device of Fig. 1A, taken along line B-B therein;

Fig. 2 A is a side view of the retractor device of Fig. 1 A in an expanded position;

Fig. 2B is a cross-sectional view of the retractor device of Fig. 2A, taken along line B-B therein;

Figs. 3A and 3B are enlarged schematic side and cross-sectional views of the multi-purpose probe of the retractor device of the present invention, seen in Figs. 1A and 2A;

Fig. 4 is a magnified sectional view of a the retractor device of the invention in an expanded position seen in situ during a surgical procedure;

Figs. 5A-5H are diagrams illustrating different steps during performance of a minimally invasive surgical procedure using the retractor device of the present invention; and

Fig. 6 is an enlarged view of a trepanned portion of a skull, after replacement of the bone and skin flaps, as seen at portion 6 of Fig. 5H. DETAILED DESCRIPTION OF THE INVENTION

Referring now to Figs. 1 A-2B, there is seen an expansible needle retractor device, referenced generally 10, constructed an operative in accordance with a preferred embodiment of the present invention. Retractor device 10 includes a generally planar base 12 which includes a lower plate 12a and an upper plate 12b which fits over and connects to lower plate 12a. An expansible needle shaped retractor element 14, having a longitudinal axis 16, is mounted within a preferably central opening 17 formed within base 12, so as to protrude generally at right angles to the base 12, and so as to protrude through lower plate 12a, as seen in Fig. 1 A.

Retractor element 14 is formed of a plurality of longitudinal ribs 18 which, together with an expansible web element 20, are fastened to an expansion mechanism, referenced generally 22, mounted between the upper and lower base plates 12a and 12b. Expansion mechanism 22 includes an outer toothed ring 24 mounted onto lower base plate 12a for selectable rotation about axis 16, and having inward facing and outward facing pluralities of teeth, respectively referenced 26 and 28. There are also mounted onto lower base plate 12a a plurality of toothed transmission wheels 30 in meshing association with inward facing teeth 26, as well as a plurality of typically radially arranged linear drive elements 32.

Each linear drive element 32 is mounted for motion in a generally radial direction, having a plurality of teeth 34 arranged in meshing association with an associated transmission wheel 30. As seen, each linear drive element 32 also has an inward-facing end 35, to which typically a single longitudinal rib 18 and an associated portion of expansible web element 20 is attached. There is also provided a drive, referenced 36, which has a drive wheel 38 mounted in a housing 40 fastened to lower base plate 12a. Drive wheel 38 is typically a high precision toothed wheel arranged in meshing engagement with the outward-facing teeth 28 of toothed ring 24. Drive wheel 38 is arranged to be driven via a spindle 41, coupled via a flexible coupling 42 to a flexible drive rod 44, arranged to be driven by a suitable, very high precision drive (not shown), such as a suitable stepping motor.

It will thus be appreciated that, initially, prior to and during insertion of retractor element 14 into a body space, element 14 is contracted so that ribs 18 engage or nearly engage each other so as to form an almost closed cylinder, as illustrated in Figs. 1A and IB. Preferably, in this contracted position, retractor element 14 has a needle like shape of no more than about 5 mm in diameter.

Activation of the drive causes a very slow rotation of drive wheel 38, as indicated by arrow 46 (Fig. IB). This then causes a corresponding rotation of toothed wheel ring 24, so as to cause a simultaneous and equal rotation of all toothed transmission wheels 30 so as to cause a radially outward linear translation of linear drive elements 32. Due to the fact that ribs 18 and extensible web element 20 are attached to linear elements 32, this radially outward motion causes a concentric expansion or extension of the retractor element 14, as illustrated in Figs. 2A and 2B. Preferably, the rate of expansion is in the region of 20 microns per second. As shown and described hereinbelow in conjunction with Fig. 4, the caisson-like structure provided by the extensible web element 20, supported by ribs 18, provides a clear field of view for a surgeon, facilitating him with a generally unobstructed work area. Retractor element 14 is constructed such that, when completely expanded, it has a diameter of up to 15 - 30 mm.

As seen in Fig. 1A, the retractor element 14 has mounted onto a free end thereof 48, a probe 50. Probe 50 is configured to be supported on free end 48 of the retractor element 14 when in the illustrated, contracted position. As the retractor element 14 expands, however, probe 50 is released, and may be manipulated for various purposes, as described below.

Referring now to Figs. 3A and 3B, in accordance with a preferred embodiment of the invention, probe 50 is a dual purpose probe, and includes ultrasound imaging capabilities as well as coagulation or cauterizing capabilities. As described hereinbelow, the provision of this dual-purpose probe enables real time imaging throughout a surgical procedure, and uncomplicated cauterizing of blood vessels in the work area, thereby preventing undesired bleeding.

In greater detail, probe 50 has a generally dome-shaped, molded hollow housing 52, formed typically of a suitable plastic. A coagulation wire 54 is wound in helical fashion about the outside of the probe housing 52, typically in a channel 53 provided for this purpose, which, when in use, applies a cauterizing current to any exposed blood vessels with which it comes into contact during use.

The housing 52 further includes, at an interior apex portion thereof, a piezoelectric crystal element 56, and a lining 58 formed of a damping material, arranged therebehind. A suitable wire 59 is connected to the crystal element 56, for providing electrical excitation of piezoelectric crystal element 56 so as to cause emission of ultrasound energy therefrom, and transfer of signals received therefrom to suitable visual display apparatus, generally as described below in conjunction with Figs. 5B and 5F, so as to provide ultrasound imaging of the work area in real time.

It will be appreciated that, while the probe 50 is described specifically as being a combined ultrasound and cauterizing probe, this is by way of example only, and additional or different functions may be provided therein, instead.

Referring now to Figs. 4-6, there is described a method of minimally invasive surgery, in accordance with a preferred embodiment of the invention. By way of non-limiting example only, the method is described in conjunction with the neurosurgical removal of a space occupying lesion, although it may be equally adapted for removal of undesired tissue from other portions of the body, where it is feasible to replace invasive surgery with a minimally invasive method, as described herein.

Referring briefly to Fig. 5A, there is seen a cut-away representation of a human skull and brain, wherein a space occupying lesion is seen at a location 60. The initial location of the lesion is performed by any suitable imaging technique known in the art, and is thus not described specifically herein. In accordance with the method of the invention, the skull is trepanned so as to remove a circular bone flap, typically having a diameter in the range 15 - 30 mm. Once an opening of desired size has been formed, as seen in Fig. 4, the retractor element 14 is carefully inserted in-between brain lobes so as to reach the lesion, as seen in Figs. 5B and 5C.

While the location of the lesion has been previously determined, the use of the ultrasound imaging properties of probe 50 during insertion of retractor element 14 enables a surgeon to view the exact location of the lesion on a monitor 58 while inserting the retractor element 14, thereby enabling him to insert the retractor element 14 with very high accuracy. As required, in order to cauterize blood vessels so as to prevent obscuration of the work area by bleeding, the coagulation portion of probe 50 may be energized, as via a pedal switch 60, and an electrocoagulation control 62 connected to a power source 64, seen in Fig. 5B.

Referring now briefly to Fig. 5C, once the retractor element 14 has been inserted to a desired depth, the retractor device 10 is firmly fastened to the skull by use of a plurality of positioning screws 66 (Figs. 1 A-2B, and 4). Subsequently, the motor (not shown) is activated so as to operate expansion mechanism 22 (Figs. IB and 2B), which, as described above, causes a concentric, radial expansion of retractor element 14, from its initial, contracted position, seen in Figs. 1A and IB, in which it may have a diameter of as little as 5 mm, to an expanded position, seen in Figs. 2A, 2B and 4, where it may have up to any predetermined, useful diameter, but typically in the range 15 - 30 mm.

As seen in Figs. 4 and 5D, once the retractor device 10 is positioned and fully expanded, there is provided, within the above-mentioned caisson-like structure formed by ribs 18 and web element 20, a work area which is clearly defined, is essentially free from blood, and in which the surgeon is able to concentrate fully on the removal of the lesion. Typically, once the retractor device 10 is properly positioned, the probe 50 may be removed by use of specially adapted forceps 68, so as to clear the way for removal of the lesion.

As seen in Fig. 5E, the lesion is removed by insertion into the work area of an endoscope and aspiration device 70, enabling the lesion to be broken down and suctioned out, while viewing progress of this procedure on the endoscope screen 72.

Subsequently, probe 50 is reinserted by use of forceps 68, so as to enable ultrasound imaging of the area, thus making sure before removal of the retractor device 10, that no lesion tissue remains.

The expansion mechanism 22 is subsequently operated in reverse, so as to contract the retractor element 14, enabling subsequent removal of the device 10, and closure of the skull opening as seen in Figs. 5H and 6, generally as known in the art.

It will be appreciated by persons skilled in the art that the minimally invasive technique of the present invention has a number of advantages over prior art, which include the following:

1. insertion of the needlelike retractor element causes less trauma to surrounding tissue than insertion of two or more retractors of the sort known in the art;

2. the concentric, radial expansion of the retractor element distributes pressure in all directions, evenly, there by avoiding undesirable localized concentrations of pressure;

3. the use of a high precision motorized drive provides a gradual expansion of the retractor element, thus providing less trauma than if performed manually;

4. the provision of a coagulation capability with probe 50, prevents excessive bleeding, reducing blood loss and keeping the work area relatively clean; 5. as a single retractor element only, is used, a single act of insertion is required, thereby further avoiding unnecessary trauma;

6. the ability to cordon off the work area in the described caisson-like manner and the consequent easier access to the work area, reduces the required size of the opening, and thus - in the case of the neurosurgical procedure described - also of the bone flap which has to be removed. This helps to reduce the outward forces applied by tissue on the bone flap after replacement thereof.

It will be appreciated by persons skilled in the art that the scope of the present invention is not limited by what has been specifically shown and described hereinabove, merely by way of example.

Claims

1. An expansible needle retractor device which includes: a base arranged for positioning over an opening in a body portion; an expandable needle shaped retractor element having a longitudinal opening and an axis extending therealong, and configured for insertion through the opening so as to extend into the body portion and thus to engage body tissue, said retractor element having a first end supported in association with said base and a second, free end, spaced axially therefrom; and expansion apparatus mounted onto said base and operative to selectably expand said retractor element radially about said longitudinal axis into an expanded position so as to retract body tissue engaged by said retractor element, and thereby to expose a working area within the body portion, in generally axial alignment with the opening.

2. An expansible needle retractor device according to claim 1, wherein said retractor element is formed of a plurality of generally rigid rib members extending from said base, joined by an extendible web, which, when said retractor element is in said expanded position, is operative to resist, together with said elongate members, return of retracted body tissue to its non-retracted state.

3. An expansible needle retractor device according to claim 2, wherein said retractor element is expansible concentrically about said longitudinal axis.

4. An expansible needle retractor device according to claim 3, wherein said rib members are connected at said first end of said needle element to said expansion apparatus, and are distributed generally evenly about said longitudinal axis, thereby to expand in concentric fashion thereabout.

5. An expansible needle retractor device according to claim 2, wherein said extendible web is a flexible membrane.

6. An expansible needle retractor device according to claim 1 , wherein said expansion apparatus is operative to expand said retractor element at a predetermined speed, thereby to provide retraction of body tissue at a corresponding rate, predetermined to minimize trauma to the tissue.

7. An expansible needle retractor device according to claim 6, wherein said expansion apparatus includes electrical drive apparatus.

8. An expansible needle retractor device according to claim 1 , and also including a probe mounted onto said second, free end of said retractor element.

9. An expansible needle retractor device according to claim 8, wherein said probe includes at least one of the group consisting of: an imaging probe; and an electrocoagulation probe.

10. A method of minimally invasive surgery, which includes the following steps: forming an opening in the exterior of a body portion located in proximity to a tissue portion sought to be surgically removed; inserting a radially expansible needle-like retractor element through the opening, through body tissue so as to reach the tissue portion sought to be surgically removed; expanding the retractor element concentrically, thereby to cause a lateral displacement of adjacent tissue, so as to expose the tissue portion sought to be surgically removed; and removing the tissue portion sought to be surgically removed.

11. A method according to claim 10, also including the step of inserting an imaging probe in association with the retractor element, thereby to provide imaging of a selected tissue portion during insertion thereof through body tissue.

12. A method according to claim 10, also including the step of inserting an electrocoagulation probe in association with the retractor element, thereby to provide selectable cauterization of blood vessels proximate thereto during insertion thereof through body tissue.

11

13. A method according to claim 10. wherein said step of forming an opening includes forming an opening of substantially same diameter as the retractor element, once expanded.

14. A method according to claim 10. wherein said step of expanding includes the step of expanding the retractor element at a preselected rate.

15. A method according to claim 14. wherein said preselected rate is in the region of 20 microns per second.

16. A method according to claim 10, wherein said step of forming an opening in the exterior of a body portion located in proximity to a tissue portion sought to be surgically removed includes forming an opening in a skull of a subject, located in proximity to a space occupying lesion sought to be removed from the subject's brain; said step of inserting a radially expansible needle-like retractor element includes inserting the retractor element between brain lobes so as to reach the space occupying lesion sought to be surgically removed; and said step of expanding the retractor element includes separating brain tissue adjacent thereto, so as to expose the space occupying lesion.

17. An expansible needle retractor device according to any of claims 1-9. and substantially as shown and described hereinabove ion conjunction with any of Figs. 1A-6.

18. An expansible needle retractor device according to any of claims 1-9, and substantially as shown in any of Figs. 1A-6.

19. A method according to any of claims 10-15, and substantially as shown and described hereinabove ion conjunction with any of Figs. 1A-6.

20. A method according to any of claims 10-15, and substantially as shown in any of Figs. 1A-6.