Abstract:
A handle and drive mechanism for providing a reciprocating rotary action of a driveshaft, first in one rotational direction and then reversing the rotational direction, suitable for suturing and other endoscopic operations.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to medical instrumentation, specifically to articulating, handheld instruments used in surgery and microsurgery and for suturing and other reversing rotary action operations. 
     BACKGROUND 
     Endoscopic medical devices allowing extracorporeal manipulation of internally disposed surgical instruments are well known. These devices typically comprise an elongate driveshaft, having a cylindrical housing journalled thereon; the driveshaft and the housing together defining a distal end and a proximal end. A variety of medical instruments, such as tweezers, scissors, suturing needles, and the like may be disposed at the distal end of the housing such that they are functionally connected to the driveshaft. Means for controlling the instruments, typically opposed handles such as those found on household shears, are disposed at the proximal end of the housing such that they too are functionally connected to the driveshaft. The distally disposed instruments are operated by the surgeon by manipulation of the handles to impart an axial or rotary motion to the driveshaft and, in turn, the instrument. 
     In order to provide the surgeon with an instrument that enables precise and steady use, it is sometimes desirable that a complete operational cycle be possible using only one cycle of the device handle. Indeed, medical device engineers have long sought to enable a surgeon to impart phases of rotary and counter-rotary motion to the driveshaft in one continuous operation of the handles. However, it has not been possible previously to provide rapid rotational and immediate counter-rotational movement to a driveshaft during the same stroke. 
     Until now, the surgeon was required to complete one operation (i.e., opening or separating the handles) in order to provide rotary motion to the driveshaft and then a second operation (i.e., closing or drawing together the handles) in order to provide counter-rotary motion to the driveshaft. This inability to impart both rotary and counter-rotary motion to the driveshaft in one continuous operation of the handles results in devices that are limited in their applications and often awkward to use. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a handle and drive mechanism for providing a reciprocating rotary motion to a driveshaft first in one rotational direction and then immediately in the counter-rotational direction, with one or more additional rotation cycles possible. 
     It is a further object of the present invention to provide a mechanism capable of allowing a complete operational cycle using only one stroke of the device handle. 
     It is an additional object of the present invention to provide a mechanism for providing reciprocating rotary motion, wherein one or more changes in rotational direction may be controlled by manual manipulation of the device. 
     It is another object of the present invention to provide both rotational and counter-rotational motions to a fixed angular degree. 
     It is yet another object of the present invention to provide a medical device capable of accommodating a variety of effector distal end instruments that require such reciprocating rotational motion to operate. 
     A still further object of the present invention to provide an instrument of this type that is relatively easy to operate using only one hand. 
     The present invention comprises a hand-operated medical device that imparts, in one continuous operation of a handle mechanism, rotary motion to a driveshaft, first in one direction and then immediately in the opposite direction. Both rotation and counter-rotation motions are performed to a fixed angular degree. The purpose of providing these rotational motions to the driveshaft is to enable operation of various mechanisms that may be disposed at the distal end of the instrument. A handle of the present invention could be used to manipulate various distal end mechanisms, such as the suturing instrument described in U.S. Pat. No. 5,437,681 to Meade et al. 
     The above-described and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments and certain modifications thereof when taken together with the accompanying drawings in which: 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a perspective view of an embodiment of the present invention at the beginning of an operational stroke. 
     FIG. 1B is a perspective view of an embodiment of the present invention midway through an operational stroke. 
     FIG. 1C is a perspective view of an embodiment of the present invention at the end of an operational stroke. 
     FIG. 2 is a close-up perspective view of an embodiment of the reciprocating gear assembly of the present invention at a changeover point. 
     FIG. 3 is a segmented elevation of the gearing cogs on the gears and gear racks of the present invention. 
     FIG. 4 is a plan view of the apparatus of the present invention. 
     FIG. 5 is a side elevation view of the handle and driveshaft shown in FIG. 4 taken through the line IV--IV&#39;. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows an embodiment of the presently claimed invention. The invention comprises a first gear 1, a second gear 2, a first driving element 3, and a second driving element 4, both first driving element 3 and second driving element 4 being functionally and opposably connected to each of first gear 1 and second gear 2. 
     First driving element 3 has a first finger loop 32, preferably designed to accommodate a thumb, attached to two gear racks 34 and 36. Second driving element 4 has a second finger loop 42, preferably designed to accommodate an opposed finger of the same hand, most preferably the middle finger, attached to two gear racks 44 and 46. 
     Each of gear racks 34, 36, 44, and 46 comprise a support segment S1, S2, S3, and S4, respectively, and a recessed gear engagement segment G1, G2, G3, and G4, respectively. Gear rack 34 is identical in construction to gear rack 44 and respective recessed gear engagement segments G1 and G3 thereof are provided throughout their length with teeth that engage gear 1. However, as shown in FIGS. 1A-1C and FIG. 3, gear racks 34 and 44 disposed such that their toothed recessed gear engagement segments G1 and G3, respectively, opposably, simultaneously and continuously engage opposite sides of gear 1. This arrangement enables the smooth, continuous, synchronous operation of first driving element 3 and second driving element 4 throughout a manipulative stroke in which first finger loop 32 and second finger loop 42 are initially biased toward each other until they reach the innermost end of their travel length and, immediately thereafter, biased away from each other until they reach the outermost end of their travel length. 
     As further shown in FIGS. 1A-1C and FIG. 2, although gear rack 36 is similar in construction to gear rack 46, their respective recessed gear engagement segments G2 and G4 thereof are provided through different portions of their length with teeth that engage gear 1, such that the teeth of either segment G2 of gear rack 36 or segment G4 of gear rack 46, but not both simultaneously, engage gear 2. In this manner, gear 2 can be driven first in a rotary direction by gear rack 36, as shown in FIG. 1A, and then in a counter-rotary direction by gear rack 46, as shown in FIG. 1B, or vice versa, depending on the arrangement of segments G2 and G4, as first driving element 3 and second driving element 4 are biased toward each other. 
     Thus, as first driving element 3 and second driving element 4 are moved through a complete cycle by manipulation of first finger loop 32 and second finger loop 42, gear 2 will experience four distinct phases of alternating rotary and counter-rotary motion. The frequency and duration of each pair of phases depends solely upon the arrangement of teeth in segments G2 and G4. E.g., six distinct phases of alternating rotary and counter-rotary motion would result if either of segments G2 or G4 were provided with teeth at the outermost portions of their length and the other segment provided with teeth intermediate between those of its opposite member and eight distinct phases of alternating rotary and counter-rotary motion would result if segments G2 and G4 were each provided with teeth through two, staggered, portions of their length. 
     FIGS. 1B and 2 show first driving element 3 and second driving element 4 at their mid-position; this is the changeover point for engagement of gear racks 36 and 46. Further motion of first driving element 3 and second driving element 4 in either direction will cause engagement of one rack and disengagement of the other. As shown in FIG. 3, each cog tooth on gear 1 and gear 2 is beveled in cross-section, enabling identical engagement with gear racks 36 and 46 regardless of the direction of engagement, thereby resulting in identical rotary motion of gear 2 in both the rotary and counter-rotary directions. With respect to gear racks 36 and 46, this feature enables precise and stable reciprocating rotary motion of a driveshaft without &#34;catches&#34; or discontinuities of motion by providing a smooth changeover of engagement from the teeth of one rack to those of the other, and, as a result, the smooth transition between rotary and counter-rotary motion of gear 2. 
     An additional benefit of this arrangement of teeth is that a surgeon can control the duration of motion in either or both the rotary and counter-rotary directions, up to a maximum determined by the length of segments G2 and G4 about the changeover point that are toothed. This is accomplished by positioning first driving element 3 and second driving element 4 such that the teeth of gear racks 36 and 46 are at a changeover point. Next, the surgeon can bias driving elements 3 and 4 toward or away from each other, depending on whether rotary or counter-rotary motion is desired. 
     FIG. 4 views the instrument handle 6 in cross section with the main body 11, distal shaft 12, and distal outer tube 13 in combination with first gear 1, second gear 2, first driving element 3, and second driving element 4. FIG. 5 shows a side elevation cross-section view of the handle and driveshaft of FIG. 4 taken through the line IV--IV&#39;. As can be seen from FIGS. 1A-1C, 2, and 5, gear racks 36 and 46 may be oriented so that they engage gear 2 in a side-by-side fashion, although it is envisioned that they may be opposably disposed, as are gear racks 34 and 44. 
     To reiterate the cycle sequence, starting with first driving element 3 and second driving element 4 in the position furthest apart from each other and cycling the instrument once, i.e., biasing them completely toward each other and then back to the original position, the driveshaft rotates in a first, rotary direction. One quarter of the way through the cycle, the driveshaft reverses direction and rotate in a second, counter-rotary direction. As the first and second driving elements are biased to the fully together position, the halfway point of the cycle is reached. As the driving elements are biased apart, the driveshaft again reverses direction rotates in the first, rotary direction. At the three-quarters point of the cycle, the driveshaft again reverses direction and completes the cycle moving in the second, counter-rotary direction. 
     In an additional contemplated embodiment, it is intended that the device housing be provided with one fixed finger loop and one driving element such that the reciprocating rotary motion of the driveshaft is accomplished solely by means of manipulating the single drive element. 
     It can now be understood that the starting rotational direction and the number and durations of gear motion phases of the mechanism can be established when manufacturing the instrument by varying the number and placement of gear teeth on gear racks 36 and 46. It may also be understood that the degree of angular rotation of gear 2 is controlled by the length of gear racks 36 and 46 and the pitch diameter of driving gear 2.