Automated biopsy instrument - Patent Review 5125413

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BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a biopsy instrument; viz., a device for removing a sample of tissue from a human being or an animal. More particularly, the invention relates to an automated biopsy instrument in which a spring-loaded outer cannula is driven over an inner stationary stylet to obtain the tissue sample.

2. Description of the Related Art

The procedure known as biopsy, or the removal of samples of human and animal internal tissue, has been for many years a favored method for the nonsurgical diagnosis of tissue. Traditionally, biopsy has been performed in a two-step manual technique employing a needle in which an outer hollow cutting cannula telescopically receives an inner stylet which is slidable between retracted and extended positions relative to the cannula. In performing the first step of the technique, the physician places the tip of the needle (with the stylet retracted inside the cannula) against the tissue mass to be sampled and manually drives the stylet forward into the tissue mass. In a typical instrument of this type, the stylet extends rearwardly therefrom and is fitted with a push-knob to facilitate the driving of the stylet in the forward direction. To carry out the second step, the physician manually drives the cutting cannula forwardly over the stylet, thereby severing a tissue sample and retaining it within the cannula's hollow interior.

Examples of manually operated biopsy needles of this general type are disclosed in U.S. Pat. No. 4,600,014, issued Jul. 15, 1986 to D. Beraha for "Transrectal Prostate Biopsy Device and Method", and U.S. Pat. No. 3,477,423, issued Nov. 11, 1969 to L. K. Griffith for "Biopsy Instrument".

Such manually operated two-step devices are awkward to manipulate, and the tissue samples obtained may often be unsatisfactory. The depths to which the stylet and the cannula are driven into the tissue mass must be carefully controlled for accuracy and efficiency. Caution is required, as well, in applying the force with which the stylet and cannula are plunged forward. Too little force may not sever the tissue sample from the mass; too much force may cause unnecessary damage to the surrounding vital tissues.

In an effort to remedy these problems, various automated devices have been developed. For example, U.S. Pat. No. 3,452,741, issued Jul. 1, 1969 to R. C. Schaffer for "Conetome", discloses an instrument for performing cervical biopsies in which an electric motor imparts reciprocating movement to a pair of serrated scalpel blades.

U.S. Pat. No. 4,667,684, issued May 26, 1987 to H. G. Leigh for "Biopsy Device", discloses a movable stylet telescopically received in a hollow movable cannula, both the stylet and the cannula being mounted to hubs within a pistol-style grip. In use, the stylet is first manually advanced into the tissue and the cannula is then driven over the stylet by depressing a trigger.

U.S. Pat. No. 4,699,154, issued Oct. 13, 1987 to one Lindgren for "Tissue Sampling Device", discloses a complicated biasing mechanism in which a release button is depressed to cause a spring-loaded stylet to be advanced into the tissue mass. The forward movement of the stylet also triggers the delayed release of a spring-loaded outer cannula, which slides over the stylet to sever the tissue sample.

The aforementioned U.S. Pat. No. 4,600,014 to Beraha discloses an embodiment in which, after a slidable stylet is manually advanced into the tissue mass, a spring-loaded outer cannula is released and driven over the stylet to sever the tissue sample.

Several prior automated biopsy instruments employ a stylet formed with an elongated transverse slot or notch ad]acent to its sharpened tip. This slot provides a pocket in which is captured a severed tissue sample when the cannula is driven forward over the stylet in the second step of the biopsy procedure. Typical of this form of stylet is the TRU-CUT.RTM. Needle marketed by Travenol Laboratories, Inc., Deerfield, Ill.

An important feature of another known device, The Roth Biopsy Needle, marketed by Cook Urological, Inc., Spencer, Ind., is a stylet which is manually adjustable between extended and retracted positions for reasons which will be apparent from the following description of its various methods of operation. The stylet is loaded from the rear of the instrument and extends behind the instrument at all times. The stylet is mounted to a U-shaped handle which is engageable with the body of the instrument in two positions corresponding to the extended and retracted stylet positions. A spring-loaded cannula is also movable between a charged or rear position and a discharged or advanced position.

In one method of using the Roth needle, the physician first adjusts the stylet manually to its retracted position and moves the cannula manually to the charged position to expose the sharpened tip of the stylet. He then penetrates the tissue mass with the stylet and depresses a button-release to cause the cannula to be driven by the spring forwardly over the tip of the stylet to sever the tissue sample and retain it within the hollow tip of the cannula. It is to be borne in mind that the stylet of the Roth needle is movable, as mentioned above, and that the button-release is exposed at all times and therefore subject to inadvertent actuation. It should also be noted that because the stylet and the associated U-shaped handle extend behind the instrument, the stylet and handle are always exposed and are therefore vulnerable to accidental impact or unintended forces, thereby creating a risk that the stylet may be inadvertently advanced into the body of the patient with possibly deleterious consequences.

In another method of using the Roth needle, the physician proceeds as before, but after penetrating the tissue mass he manually advances the stylet to its extended position to expose the transverse slot or gap therein described above. When the cannula is advanced, the tissue sample is severed and captured in the pocket formed by the slot.

In an alternative variation of the foregoing method, the physician may begin the procedure with the stylet in the extended position and the cannula in the discharged mode. Once the tissue has been penetrated, the cannula is manually retracted to expose the transverse slot. However, it is to be noted that all stylets formed with such a tissue pocket, whether employed in the Roth needle or in other biopsy instruments, become unstable when tooled to gauge sizes larger than 20 gauge (i.e., 21, 25 gauge). At higher gauge numbers (i.e., smaller diameter stylets) the bridge joining the stylet's proximal and distal ends at the tissue pocket becomes increasingly flexible, and therefore the stylet becomes physically unstable and its direction impossible to control with any precision when the slot or gap is exposed during penetration of the tissue mass by the stylet. Moreover, certain areas of the body such as the pancreas, thyroid, and nonpleural-based intrapulmonary lesions are routinely biopsied with needles smaller than 20 gauge (i.e., 21 gauge) to reduce the incidence of hemorrhage and pneumothorax.

In any event, the various automated biopsy instruments presently known tend to be heavy, difficult to manipulate, and incorporate biasing mechanisms which are either complicated in construction or require undue force to operate. Such limitations diminish the physician's control over the instrument and the precision with which biopsies may be performed. These instruments may be subject to inadvertent movement or torque which may, in turn, subject the patient to unnecessary trauma and risk. This is especially true of instruments which permit or require adjustment of the relative positions of any of their elements before the cannula is moved forward to sever the tissue sample. Similarly, the length of time required to perform a biopsy increases as the physician's degree of control of the instrument decreases, further elevating the risk to which the patient may be exposed. Finally, both physician and patient are exposed to the risk of inadvertent advancement to the cannula when the instrument is in its charged condition.

SUMMARY OF THE INVENTION

The present invention provides, in a biopsy needle support assembly comprising a casing, means for mounting a biopsy needle, the needle mounting means being carried by the casing for alternation between a charged condition and a discharged condition, means for urging the needle mounting means to the discharged condition, manually operable charging means for urging the needle mounting means to the charged condition, and release means for retaining the needle mounting means in the charged condition, the release means being actuable to release the needle mounting means from the charged condition, the improvement wherein the charging means comprises shield means carried by the casing for movement relative thereto to and from a position blocking actuation of the release means when the needle mounting means is in the charged condition.

It should be noted at this juncture that the term "distal" is used herein in its ordinary sense to mean "remote from the point of attachment", and that the term "proximal" is used hereinafter in its meaning of "at, adjacent to or near the point of attachment."

In preferred embodiments of the invention, a shield means is provided which is disposed to block or prevent inadvertant actuation of the release means. More particularly the charging means preferably includes the shield means and is movable between the safety position and a charged-ready position in which the shield means is displaced from the safety position to expose the release means for actuation.

Other features and advantages of the invention will be apparent from the ensuing description in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an exploded perspective view of the major components of a biopsy instrument comprising an embodiment of the invention;

FIG. 1A is a perspective view of the biopsy instrument of FIG. 1 in a fully assembled condition;

FIG. 2 is a longitudinal sectional view taken along line 2--2 of FIG. 1A and showing the biopsy instrument of FIGS. 1 and 1A in a "charged-safety-on" mode;

FIG. 3 is a longitudinal sectional view of the biopsy instrument of FIGS. 1, 1A and 2, taken along line 3--3 of FIG. 1A;

FIG. 4 is a longitudinal sectional view similar to FIG. 2 but showing the biopsy instrument of FIGS. 1 to 3 in a "charged-ready" mode;

FIG. 4A is a longitudinal sectional view similar to FIG. 2 but showing the biopsy instrument of FIGS. 1 to 4 in a "discharged" mode;

FIG. 5 is an exploded perspective view similar to FIG. 1 but showing a biopsy instrument comprising an alternative embodiment of the invention;

FIG. 5A is a perspective view of the biopsy instrument of FIG. 5 in a fully assembled condition;

FIG. 6 is a longitudinal sectional view taken along line 6--6 of FIG. 5A and showing the biopsy instrument of FIGS. 5 and 5A in a "charged-safety-on" mode;

FIG. 7 is a longitudinal sectional view of the biopsy instrument of FIGS. 5, 5A and 6, taken along line 7--7 of FIG. 5A;

FIG. 8 is a longitudinal sectional view similar to FIG. 6 but showing the biopsy instrument of FIGS. 5 to 7 in a "charged-ready" mode;

FIG. 8A is a longitudinal sectional view similar to FIG. 6 but showing the biopsy instrument of FIGS. 5 to 8 in a "discharged" mode; and

FIG. 9 is a fragmentary view of an alternative form of a stylet for a biopsy instrument according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and particularly to FIGS. 1 and 1A, an automated biopsy instrument according to the invention is designated generally by the reference numeral 10. The instrument 10 comprises seven principal elements, which will be more fully described hereinbelow: an outer casing 12; an inner support rod 14; a coil spring 16; a biopsy spring guide 18; a safety cap 20; a release lever 22; and a needle 24.

The outer casing 12 comprises an elongated hollow cylindrical tube 26 open at a rear end 28 thereof and substantially closed by an end wall 30 which is formed integrally with the tube 26 at the opposite or forward end 32 thereof. The open end 28 is closed by a cap 31. A cannula slot 34 in the end wall 30 communicates with a hollow interior 35 of the tube 26. The slot 34 extends radially from a center point of the end wall 30 to the periphery thereof. A cone-shaped depression 34a is formed in the interior face of the end wall 30 at the closed end of the slot 34, the broader end of the depression 34a opening toward the interior 35 of the tube 26.

Provided in the tube 26 at the forward end 32 thereof, and spaced from the end wall 30, are a pair of substantially rectangular access ports 36a and 36b which communicate with the hollow interior 35 of the tube 26. Access port 36a circumscribes an arc of approximately 90 degrees about the circumference of the outer casing 12, communicates with the cannula slot 34 at an intersection designated by the reference character 33, and extends symmetrically in either direction from the intersection 33. Access port 36b is diametrically opposite from port 36a and is identical therewith except that it does not communicate with the cannula slot 34.

The outer casing 12 includes a release lever seat 38 provided by a rectangular aperture which is formed in the tube 26 and communicates with the interior 35 thereof. Seat 38 is positioned approximately at the longitudinally central portion of the tube 26 and in line with the cannula slot 34.

The outer casing 12 is additionally provided with a pair of longitudinal guide slots 40 which are formed in the tube 26 and extend from the rear end 28 thereof toward the opposite or forward end 32. The guide slots 40 are disposed diametrically oppositely from one another and approximately midway between, or 90 degrees from, the access ports 36a, 36b.

The internal support rod 14 comprises an elongated solid cylindrical shaft 42 joined to a circular or disc-shaped base 44. An anchor socket or clevis 46 is formed in the distal end of the shaft.

The biopsy spring guide 18 is hollow and open at its opposite ends and comprises a forward cylinder 48 and a rear cylinder 50 joined coaxially therewith. The outside diameter of the forward cylinder 48 is smaller than that of the rear cylinder 50, the forward cylinder 48 communicating with and extending from the rear cylinder 50. An annular internal shoulder 52 is formed in the rear cylinder 50. The walls of the two cylinders are continuous, thereby forming an annular external shoulder 54. The exterior surface of the distal end of the forward cylinder is formed with a quarter-turn male thread 56.

The needle 24 comprises a cannula mount 58 and a stylet 60. The cannula mount 58, in turn, comprises a cylindrical collar 62, a conical head 64, and a cutting cannula 66. The collar 62 is open at one end thereof and is closed at its opposite end by an end wall 68 pierced by a centrally disposed, narrow axial bore 69 (FIG. 2). An outer surface 70 of the collar 62 is provided with knurling 71 for improved grip, while an inner surface 72 is formed with a quarter-turn female thread 74 adapted to mate with the thread 56 of spring guide 18. The conical head 64 is secured to the end wall 68 over the axial bore 69, and is itself axially bored to communicate with the interior of the cylindrical collar 62 by way of bore 69, whereby the cutting cannula 66 is received by the head 64 and end wall 68 and is there secured in any suitable manner. The cutting cannula 66 comprises a hollow tube which is beveled to an appropriate angle at its distal end 76 (the particular angle depending on the style of cannula employed) and sharpened about its circumference at the distal end 76.

It will be noted at this point that the hollow interior of the cannula is in communication with the interior of collar 62.

Although the cutting cannula 66 is described as being of a certain configuration, it is not so limited. Because the cannula mount 58 is detachably affixed to the spring guide 18, the biopsy instrument 10 may interchangeably employ a needle having any one of several configurations well known in the art, including but not limited to those variously known by or marketed under the names Turner, Chiba, Franseen, Tip-cut, Menghini, and Bernardino/Sones. The biopsy instrument 10 may also employ a TRU-CUT needle, as discussed more fully hereinafter.

The stylet 60 is sharpened to a point at its distal end 78 and is formed with an anchor 80 at its proximal end 82. It will be apparent that the stylet need not be formed with a tissue pocket or sampling gap; that is, a transverse slot located adjacent to the sharpened distal end 78, as will be discussed with greater particularity hereinafter.

The safety cap 20 or shield means is a roughly bell-shaped hollow element open at both ends and surrounding the cylindrical tube 26. A web 84 thereof joins a narrow, hollow cylindrical forward section 86 to a hollow cylindrical rear section 88 of greater diameter than the forward section 86. The rear section 88 is formed with a series of circumferential ribs 90 for improved grip, and it will be noted that configuration of the safety cap 20 is such that it may be encirclingly engaged or grasped by the thumb and fingers of one hand. Integrally formed on an interior surface 92 of the forward section 86 of the safety cap, at a point where the forward section 86 and the web 84 merge, are a pair of oppositely disposed, elongated guide pins 94 of square cross section.

The release lever 22 comprises a finger rest 96 and a mounting section 98 maintained in spaced parallel planes by a connecting web 100. The finger contacting surface of the finger rest 96 may be appropriately textured for improved grip. Mounting section 98 is formed with a latching projection 102 at one end of the release lever and is flexibly secured to the outer casing 12 by a spot weld 104 (FIG. 2).

In assembly, a biasing means in the form of the coil spring 16 is coaxially received over the cylindrical shaft 42 of the internal support rod 14 with a first end l6a of the spring bearing against the base 44 to which the shaft 42 is mounted. The rod 14 and the spring 16 are in turn telescopically received within the biopsy spring guide 18 with a second or opposite end 16b of the spring 16 bearing against the internal shoulder 52 of the spring guide.

Next, the support rod 14, the coil spring 16, and the spring guide 18 are telescopically received within the outer casing 12, and the subassembly so formed is then received within the safety cap 20 with the guide pins 94 thereof registering with the guide slots 40 in the outer casing 12. The safety cap 20 is slidable over the outer casing 12, the extent of forward movement thereof being limited by the length of the guide slots 40. The rear end 28 of the tube 26 is closed by the cap 31.

The stylet 60 is telescopically or coaxially received within