Abstract:
A suture retainer for use with a surgical instrument comprises a slot defined in the surgical instrument, the slot having a bottom and lateral slot ends. A retainer block comprises a bottom and lateral block ends. The lateral block ends and the lateral slot ends are configured to matingly engage to define a v-shaped gap adjacent a lateral slot end near a mouth of the slot.

Description:
RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Patent Application Ser. No. 60/567,030, filed Apr. 29, 2004, entitled “Suture Retainer Attachment for Use with a Surgical Retractor,” which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention is generally directed to Surgical Devices, and more particularly to a suture retainer for use with, for example, a surgical retractor. 
     BACKGROUND ART 
     Surgical retractors of various configurations are known in the art. Representative is a surgical retractor sold by Genesee Biomedical, Inc. under the trademark SRC-AR™ and which is described in Wright, U.S. Pat. No. 5,772,853, the contents of which are incorporated by reference in their entirety herein. Other examples of surgical retractors include the Genzyme-OPCAB Elite™ system sold by Genzyme Surgical Products Corporation; the Medtronic Octobase™ retractor system sold by Medtronic, Inc. and the Guidant Acrobat™ off-pump system retractor sold by Guidant Corporation. 
     Each of the Genzyme-OPCAB Elite™ system, the Medtronic Octobase™ retractor system and the Guidant Acrobat™ retractor system include integral suture retainers. These retractors are of particular utility in off-pump coronary artery bypass surgery. During off-pump, beating heart coronary artery, bypass surgery it is advantageous to place the patient in a steep Trendlenburg position and to elevate the apex of the left ventricle. To achieve elevation of the apex of the heart a series of surgical sutures are placed around the posterior wall of the pericardium. Typically, the sutures are made of silk or a monofilament size 2, 1 or 0. In order to maintain the apex of the heart in the desired position, the sutures must be secured to a suitable fixture such as the arms of a retractor. Thus, each of the Genzyme-OPCAB Elite™ system, the Medtronic Octobase™ retractor system and the Guidant Acrobat™ retractor system include suture retainers spaced lengthwise of the retractor arms. Ideally these suture retainers assist not only in fastening the sutures to the retractor arms to maintain the apex the heart in the desired elevated position, but also function to organize the sutures to assist in speeding the surgical procedure. 
     The Genzyme-OPCAB Elite™ system has channels for receiving sutures, but requires locking forceps to be used in conjunction with the channels to hold the sutures in a select position. Use of these locking forceps can complicate the surgical procedure, requires introduction of additional apparatus into an already crowded operating field and increases the time to complete a procedure by requiring manipulation of numerous locking forceps. 
     Both the Medtronic Octobase™ and the Guidant Acrobat™ retractors offer improvement to the Genzyme-OPCAB Elite™ system by providing self-locking suture retainers as integral elements with the surgical retractor arm for both organizing and grasping surgical sutures. In each instance the suture retainers include a cam element operatively associated with a suture channel. The cam element pivots to grasp and retain the suture within the suture channel to prevent axial withdrawal of the suture from the suture channel. While these cammed suture retainer structures offer a clear advantage over the use of locking forceps in systems like the Genzyme-OPCAB Elite™ system, use of the mechanical cam system presents some serious problems. First, these devices are disposable and relatively expensive (reusable devices would be very difficult to clean and the locking cams could be locked in a non-gripping position by dried blood or debris generated in a surgical procedure and thus rendered inoperative). In addition, the prior art locking cams have many small components that potentially might become detached and fall into the patient&#39;s chest cavity. 
     The present invention is directed towards overcoming one or more of the problems discussed above. 
     SUMMARY OF THE INVENTION 
     A first aspect of the present invention is a suture retainer for use with a surgical instrument. The suture retainer comprises a slot defined in the surgical instrument, the slot having a bottom and lateral slot ends. A retainer block comprises a bottom and lateral block ends. The lateral block ends and the lateral slot ends are configured to matingly engage to define a v-shaped gap adjacent a lateral slot end near a mouth of the slot. In one embodiment the slot includes lateral block ends at an obtuse angle relative to the slot bottom and the lateral block ends are at an obtuse angle relative to the block bottom substantially equal to the obtuse angle between the lateral slot ends and the slot bottom so that the retainer block fits snugly within the retainer slot. The lateral block ends further include a portion opposite the block bottom within a plane that is at an angle less than the obtuse angle relative to the block bottom to define the v-shaped gap. In another embodiment, the retainer block comprises a post extending from the block bottom and the slot in the instrument has a cavity in the bottom configured to receive the post with the lateral block ends and the lateral slot ends in abutment. This embodiment may further include the posts having first and second resilient legs biased to maintain a lengthwise gap therebetween. Each of the first and second legs has a detent extending oppositely of the detent of the other leg. The cavity in the bottom slot has opposed holes defined therein, the holes being configured to receive the post detents with the retainer block fully inserted into the retainer slot with the lateral block ends and lateral slots ends in abutment. A space may be defined between the slot bottom and the retainer block bottom with the lateral block ends and the lateral slot ends in mating abutment. 
     A second aspect of the invention is a suture retainer block for use with a surgical instrument, the surgical instrument defining a slot having a slot bottom between opposing lateral slot ends. The suture retainer block comprises a body having lateral block ends separated by a block bottom. The lateral block ends are configured to matingly engage with the opposing lateral slot ends near the block bottom and the slot bottom and to define a v-shaped gap adjacent the lateral slot ends near a mouth of the slot. The surgical instrument may further include a cavity defined in the slot bottom. With such an embodiment, the suture retainer block further comprises a post extending from the block bottom and configured to be received in the cavity with the lateral block ends and the lateral slot ends in abutment. The cavity in the bottom of the slot may include opposed holes defined therein. With such an embodiment the post of the suture retainer block further includes first and second resilient legs biased to maintain a lengthwise gap therebetween. Each of the first and second legs has a detent extending oppositely of the detent in the other leg. The detents are configured to be received in the holes in the cavity with the retainer block fully inserted into the retainer slot with the lateral block ends and the lateral slot ends in abutment. 
     The suture retainer of the present invention enables the secure attachment of sutures to a surgical instrument while enabling the suture retainer to be disassembled to permit sterilization and reuse of the surgical instrument. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a surgical retractor including suture retainers in accordance with the present invention; 
         FIG. 2  is a plane view of the retractor of  FIG. 1  including a partial cross-section of a suture retainer slots; 
         FIG. 3  is an enlarged cross-section view of a suture retainer slot of  FIG. 2 ; 
         FIG. 4  is a perspective view of a suture retainer block in accordance with the present invention; 
         FIG. 5  is a plane view including a partial cross-section of the suture retainers of  FIG. 1  in accordance with the present invention; 
         FIG. 6  is an enlarged cross-section view of a suture retainer of  FIG. 5 ; 
         FIG. 7  is a cross-section of a suture retainer in accordance with the present invention taken at 90° from the cross-section view of  FIG. 6 ; and 
         FIG. 8  is a cross-section of an alternate embodiment of a suture retainer in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a perspective view of a surgical retractor including suture retainers  20  in accordance with the present invention. The surgical retractor includes a pair of opposing arms  12 ,  14 . Similar to the retractor described in detail Wright, U.S. Pat. No. 5,772,583, the contents of which are hereby incorporated by reference herein, the arm  14  is moveable on the rack  16  relative the arm  12  to enable retraction of a sternum or thorax for gaining access for cardiovascular surgery, principally coronary artery bypass surgery carried out a beating heart. The surgical retractor is preferably made of stainless steel, but suitably rigid polymers or other metals may be used as well. Spaced lengthwise of each of the arms  12 ,  14  are a number of suture retainers  20 . As illustrated in  FIG. 1 , the suture retainers  20  are retaining lengths of sutures  22 , with only portions of the sutures  22  shown for the sake of clarity. Each of the suture retainers  20  consist of a retainer slot  24  (see  FIG. 2 ) receiving a retainer block  26 . The retainer slots may preferably be produced using wire electrical discharge machining for high accuracy and appropriate surface finish. 
     Referring to  FIG. 2 and 3 , the retainer slot  24  includes a slot bottom end  28  and opposing lateral slot ends  30 . Referring to  FIG. 3 , which shows the retainer slot in a lengthwise cross-section, the retainer slot  24  further includes a cavity  32  extending into the arm  12  in a direction opposite of mouth  34  of the retainer slot  24 . The cavity  32  in the slot bottom end  28  is preferable cylindrical, but can have any cross-section such as any polygon. On opposing sides of the cavity  32  are provided holes  36 . In one embodiment the opposing lateral slot ends  30  are each at angle θ° that is at an obtuse angle from a plane of the retainer slot bottom end  28 . An angle θ of about 95° is acceptable. 
       FIG. 4  is a perspective view of a retainer block  26 . The retainer block  26  consists of a generally rectangular body  40  having lateral block ends  42 . The retainer block  26  has a thickness that is generally equal to a thickness of the retainer arms  12 ,  14 , as best seen in  FIG. 1 . The rectangular body  40  further includes sidewalls  44  having a cavity  46  configured to make it easier for user to grasp a retainer block  26  for insertion into and removal from the retainer slots  24 . Extending substantially normal from a bottom wall  48  of the retainer block  26  is a post  50 . In the illustrated embodiment, post  50  has a cross-section of the same shape as the cross-section of the cavity  32 . In  FIG. 4  the post  50  is cylindrical and has an outer diameter slightly smaller than an inner diameter of the cavity  32 . The post  50  of  FIG. 4  consists of semi-cylindrical first and second legs  52 ,  54 . The distal end  56  of each of the first and second legs  52 ,  54  is preferably rounded. A gap  58  separates the first and second legs  52 ,  54 . Each leg has a detent  60  that extends substantially opposite the detent of the other leg. 
     Each of the lateral block ends  42  has a first surface  62  and a second surface  64 . Each of the first surfaces  62  are at an obtuse angle to the bottom wall  48 , for example, an angle θ° substantially equal to the angle θ° (e.g., 95°) between the opposing lateral block ends  42  of the retainer slot  24  and the retainer slot bottom end  28 . The second surfaces are at an angle less than θ from the plane of the bottom  48 . For example, the second surfaces may be substantially parallel to each other and perpendicular to a plane of the bottom wall  48 . 
     In one embodiment the retainer block  26  is integrally formed (i.e. injection molded) from any suitably resilient polymeric material. The polymeric material is preferably resilient enough to bias the legs  52 ,  54  to maintain the gap  58  between the first and second legs  52 ,  54 . The resilient material preferably also has a coefficient of friction helping to secure a suture in the v-shaped gaps  66 , yet sufficient hardness to neither wear from repeated insertion and removal of sutures nor be deformed by the sutures nor abrade the sutures. One representative material is ABS Lustron containing 20% Barium Sulfate, the latter being to render the device radiopaque. 
     The resilient polymer from which the retainer blocks  26  is made not only secures the pericardial sutures within the v-shaped gaps  66 , it assists in securing the post legs within the receiving cavity of the retainer slot. The cavities  46  in the sidewalls of the retainer blocks  26  assist a user in griping the retainer blocks during insertion and removal of the retainer blocks from the retainer slots. Thus, a suture retainer in accordance with the present invention provides the necessary function of securing sutures while the retainer blocks are readily removable and disposable to facilitate cleaning and sterilization of the surgical retractor. If desired, ribs or other texturing can be provided in either the opposing lateral slot ends  30  or the lateral block ends  42  to enhance gripping of a suture. 
       FIGS. 5 and 6  illustrate retainer blocks  26  received in the retainer slots  24 . Referring more particularly to  FIG. 6 , which shows a retainer block  26  received a retainer slot  24  in cross-section, the first surfaces  62  of the opposing lateral block ends mate with the opposing lateral slot ends  30 . Clearance gap  70  ensures that precise mating between first surface  62  of the opposing lateral block ends with the opposing lateral slot ends  30 , and allows for manufacturing tolerances. The post  50  is axially received in the cavity  32 , and the detents  60  mate with the holes  36 . The second surfaces  64  of the lateral block ends  42  along with the opposing lateral slot ends  30  define v-shaped gaps  66 . In the embodiment of  FIG. 6 , the corresponding corners of the retainer block  26  and the retainer slot  24  are rounded to define an expanded mouth the v-shaped gaps  66 . The v-shaped gaps  66  define a finely tapered receptacle for the sutures  22  which secure the sutures therein, as best seen in  FIG. 1 . 
       FIG. 7  shows the retainer slot  24  with the retainer block  26  received therein at a cross-section rotated 90 degrees from the cross-section illustrated in  FIG. 6 . This cross-section illustrates the detents  60  extending into the holes  36 . As described above, the retainer block  26  is preferably integrally formed of a suitable resilient polymeric material so that the first and second legs  52 ,  54  are biased to maintain the gap  58  there between. Thus, as the post  50  is axially inserted into the hole  32  the detents  60  cause the gap  58  to close somewhat until the detents  60  snap into the cavities  36 , where upon the resiliency of the legs helps to maintain the retainer block  26  in the retainer slot  24 . The cavities  46  of the retainer block  26  allow a user&#39;s finger tips to grip the retainer block  26  so as to remove it against the bias of the first and second legs  52 ,  54 . Referring to  FIG. 6 , in the illustrated embodiment the tolerances between the retainer block  26  and the retainer slot  24  are such that the retainer block  26  is prevented from rotating relative to the retainer slot by engagement of the first surfaces  62  of the lateral block ends  42  with the opposing lateral slot ends  30  of the retainer slot  24 . This stability helps maintain the v-shaped gap  66  to secure a suture therein and prevents rotation about the axis of the post  50 . 
     In use, the retainer blocks  26  are axially inserted into the retainer slots as described above in advance of performing a surgical procedure. Sutures can then be attached to tissue to be elevated and secured in place by jamming the suture into the v-shaped gaps  66 . To remove a suture from the v-shaped gap, a surgeon need only grab the free end of the suture and pull it out of the v-shaped gap. Following a surgical procedure, each of the retainer blocks  26  are removed and discarded. The retractor can then be relatively easily cleaned and sterilized with little concern for the suture retainers trapping blood or other disease vectors. 
       FIG. 8 , illustrates a second embodiment of the suture retainer  20 ′ in accordance with the present invention. In the embodiment shown in  FIG. 8 , the opposing lateral slot ends  24 ′ are comprised of first surface  80  and second surface  81 . Each of the first surfaces  80  are at an obtuse angle to the bottom wall  28 ′, for example, an angle θ° of about 95°. Each of the second surfaces  81  are at an obtuse angle to the bottom wall  48 , for example, an angle θ°+5° or about 100°. 
     Each of the lateral block ends  42  has a surface  82 . Each of the surfaces  82  are at an obtuse angle to the bottom wall  48 ′, preferably an angle θ° substantially equal to the angle θ° between the opposing lateral block ends  80  of the retainer slot face  80  and the retainer slot bottom end  28 . 
     The second surfaces  81  of the lateral slot ends  24 ′ are in a plane at an acute angle to the plane of the lateral block end wall  83 , so as to define v-shaped grooves  66 ′.