Abstract:
A retractor for surgery includes a retractor body and an elongated and expandable structure attached to the retractor body. The expandable structure, when expanded, has an elongated open interior for the insertion of a portion of a surgical instrument. Drive structure is provided for expanding the expandable structure. A retractor system and method for retracting an incision are also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not applicable.  
       BACKGROUND OF THE INVENTION  
     FIELD OF THE INVENTION  
       [0002]     This invention relates generally to surgical instruments, and more particularly to retractor instruments and methods.  
         [0003]     Minimal access surgery or percutaneous surgery utilizes a small skin incision approximately 10 mm long. A muscle-tissue dilator is then inserted through the incision in order to further expand the wound to about 24-32 mm in diameter to facilitate the insertion of surgical instrumentation and implants. The muscle-tissue dilator is a surgical retractor that reduces the need for large, open incisions, tissue scarring and pain.  
         [0004]     Prior methods and devices for retracting incisions utilize a series of rigid tubes of varying diameters and lengths. Each tube is sequentially-sized of increasing diameter such that one can be fitted over the other and individually pushed through the incision, fascia, and muscle bed toward the surgical site of interest. The tubes cannot be pushed too deeply, as they may strike vital structures such as the spinal cord, nerves, or blood vessels. The potential for improper placement and manipulation of the tubes may be dangerous and commonly requires x-ray imaging during each successive tube placement to verify tube position. As only a portion at the end of the tube serves to pry open tissue during placement, strong muscle resistance acts to expulse the tube, which sometimes results in the necessity to reposition the tube. This process is prone to placement error, dangerous manipulation, increased radiation exposure, and additional surgical time. It would therefore be desirable to provide a retractor device and method which save time and do not require repetitive manipulation, avoid undue force in placement in the incision, require less x-ray (radiation) exposure to the patient and medical staff, and which will effectively retain a proper position in the incision.  
       SUMMARY OF THE INVENTION  
       [0005]     A retractor for surgery includes a retractor body and an elongated and expandable structure attached to the retractor body. The expandable structure, when expanded, has an elongated open interior for the insertion of a portion of a surgical instrument. Drive structure is provided for expanding the expandable structure.  
         [0006]     The expandable structure can have any suitable construction. In one aspect, the expandable structure is an elongated coil. The drive structure expands and retracts the diameter of the coil. The drive structure can be any suitable structure. In one aspect, the drive structure comprises gears which engage the coil at drive surfaces.  
         [0007]     The expandable structure in another aspect comprises at least first and second portions. The drive structure moves the first and second portions relative to one another. The first and second portions can be curved or substantially C-shaped (semi-circular or elliptical) in cross-section.  
         [0008]     The drive structure can be moveable within the retractor body or can be external to the retractor body and lockable in position to maintain retractor body securely in a desired position unless unlocked to resume opening or closure of retractor body. A K-wire can be provided to assist in positioning the device.  
         [0009]     In another aspect, the expandable structure comprises retractor arms. The drive structure is operable to expand the retractor arms.  
         [0010]     A retractor system for surgery comprises a retractor body having elongated and expandable structure attached to the retractor body. The expandable structure, when expanded, has an elongated open interior space for the insertion of a surgical instrument. Drive structure is operable to expand the expandable structure. At least one surgical instrument is positionable in the open interior space. These include bone drill bits, curettes, probes, endoscopes, cautery devices, as well as other instruments.  
         [0011]     A method for retracting an incision includes the steps of providing a retractor comprising a retractor body with elongated and expandable structure attached to the retractor body. The expandable structure, when expanded, has an elongated open interior space for the insertion of a surgical instrument. Drive structure is provided for expanding the expandable structure. The retractor is inserted into the incision. The drive structure is then operated to expand the expandable structure. A surgical instrument can then be inserted at least in part through the open interior space of the expandable structure. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     There is shown in the drawings embodiments which are presently preferred, it being understood, however, that the invention can be embodied in other forms without departing from the spirit or essential attributes thereof, wherein:  
         [0013]      FIG. 1  is a perspective view of a retractor system according to the invention.  
         [0014]      FIG. 2  is an exploded view of a retractor system according to the invention.  
         [0015]      FIG. 3  is a perspective view of a retractor system in a closed position with transmission gear cover removed for visualization of the drive mechanism.  
         [0016]      FIG. 4  is a perspective view of a retractor system in the open position.  
         [0017]      FIG. 5  is a perspective view of a retractor according to the invention in an open position.  
         [0018]      FIG. 6  is a cross-section taken along A-A in  FIG. 5 .  
         [0019]      FIG. 7  is a cross-section taken along B-B in  FIG. 5 .  
         [0020]      FIG. 8  is a perspective view of a retractor according to an alternative embodiment.  
         [0021]      FIG. 9  is a cross-section of expandable structure according to an alternative embodiment.  
         [0022]      FIG. 10  is a side elevation, partially broken away and partially in phantom, of drive structure in a first position.  
         [0023]      FIG. 11  is a side elevation of drive structure in a second position.  
         [0024]      FIG. 12  is a perspective view, partially broken away and partially in phantom, illustrating a retractor according to an alternative embodiment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     There are shown in  FIGS. 1-7  an embodiment of a retractor  30  having expandable structure  38  and drive structure  40 . The expandable structure  38  can have any suitable shape, but is at least in part elongated and, when in the open position, has an open interior space into which can -be positioned a surgical instrument. The expandable structure  38  shown in  FIGS. 1-7  is an elongated coil, although other expandable structures are possible. The elongated coil  38  connects to the drive structure  40  such that the drive structure  40  is operable to expand the coil from a closed position, shown in  FIG. 3 , to an open position shown in  FIG. 4 .  
         [0026]     The manner in which the drive structure  40  expands the expandable structure  38  can be varied. In the embodiment shown in  FIGS. 1-7 , the elongated coil  38  includes slots  44  defining drive surfaces  48 . The drive structure  40  includes an elongated shaft  52  ( FIG. 2 ) having gears  56  having gear teeth  60  which engage the slots  44 . Suitable structure such as a drive head  64  is provided for engaging and rotating the shaft  52 . In this manner, the teeth  60  of gears  56  are moved within slots  44  and engage the drive surfaces  48  to expand the coil  38  from the closed position to the open position. In a reverse direction of rotation, the action of the drive structure  40  retracts the coil from the open position to the closed position. A cover  66  can be positioned over the drive shaft  52  to prevent tissues from entering the drive structure.  
         [0027]     The device can be made by any suitable process. In one process, the elongated coil  38  is manufactured from a planar sheet of material. Locking tabs  68  are folded over the elongated shaft  52  between the gears  56  so as to secure the shaft  52  to the coil. The opposite end of the planar sheet is then rolled into a coil and the slots  44  engaged to the teeth  56  to hold the sheet in the coiled position. The cover  66  can then be positioned over the shaft  52  and tabs  68 .  
         [0028]     Operation of the drive structure causes the coil  38  to unwind from the closed position shown in  FIG. 3  to the open position shown in  FIG. 4-7 . As shown in  FIG. 4 , the expanded diameter defines an open interior space  76  into which a suitable surgical instrument can be inserted, such as bone drill bits, curettes, probes, suction, cautery, endoscope and other surgical instruments.  
         [0029]     Other structure can be provided with the retractor. There is shown in  FIGS. 1-2  a K-wire  70  which passes through a head  74 . The head  74  can rest or temporarily attach onto an edge  82  of the coil  38  when the coil  38  is in the closed position, as shown in  FIG. 1 . The K-wire  70 , as is known in the art, has a positioning point  78  which is driven into the bone or soft tissue in order to guide the device and possibly other surgical devices. Expansion of the coil  38  after insertion permits the removal of the K-wire and/or head  74  as desired. The head  74  can have a suitable bore through which the K-wire  70  is mounted, such that the head  74  can be removed while the K-wire  70  remains in place to guide surgical instruments.  
         [0030]     There is shown in  FIG. 8  an alternative embodiment  100  in which drive structure  104  is provided and connected to expandable structure  108 . The expandable structure  108  is comprised of a first section  114  and second section  118  which are semi-cylindrical and mated. Operation of the drive structure, as by operation of a drive head  128 , causes rotation of the shaft  104  which causes the sections  114 ,  118  to slide past one another from a closed position to an open position. Locking structure can be provided to prevent the ends of the sections  114 ,  118  from moving past one another. These can be interlocking hooked portions or a groove and protrusion configuration.  
         [0031]     There is shown in  FIGS. 9-11  an alternative embodiment. In this embodiment, expandable structure  130  comprises a fixed internal tube  132  and mated sections  134 ,  138 , which are generally semi-spherical in cross-section as shown. The sections  134  and  138  can move past one another. Protruding ends  140  prevent the sections  134  and  138  from becoming disengaged.  
         [0032]     Drive structure is provided to drive the sections  134  and  138  of the expandable structure  130  apart from a closed to an open configuration. Any suitable drive&#39;structure is possible. There is shown in  FIG. 10 a  drive structure having a drive wedge  162  and arms  170 . Operation of the wedge  162  is by a T-handle  166  which causes threads  168  to advance the drive wedge  162  and open drive arms  170  from the closed position shown in  FIG. 10  to the open position shown in  FIG. 11 . This action will cause the first section  134  to move away from the section  138  such that the expandable structure  130  moves from the open position to the closed position.  
         [0033]     There is shown in  FIG. 12  an alternative embodiment  200 . In this embodiment, a elongated body  204  has expandable structure comprising arms  208 . The arms  208  are joined to a screw block  210  by members  212 . The members  212  are pivotally connected at connections  216  to the drive block  210  and by pivotal connections  220  to the arms  208 . A drive handle  240  is provided and operated by a threaded member  246 . Rotation of the handle  240 , and thereby threads  246 , causes advancement of the screw block  210  and opening of the expandable arms  208  from the closed position shown in  FIG. 12  to the open position shown by phantom lines in  FIG. 12 . A K-wire  260  can be threaded through an opening  264  to assist in positioning of the device. The device can be removed while the K-wire  260  remains in place.  
         [0034]     According to a method of the invention, a retractor according to the invention is positioned in an incision. Drive structure is operated to expand elongated expandable structure from a closed position to an open position. This expansion can incremental or be substantially continuous, such that the expandable structure can be expanded to any of a plurality of different dimensions. An open interior within the expandable structure provides the insertion of a surgical instrument. Also, an access port tube structure as can be positioned within or over the expandable structure to permit the retractor to be removed. The tube will retain the incision in the retracted position, and the problems of the prior art resulting from the insertion and removal of multiple differently dimensioned tubes can be avoided.  
         [0035]     The retractor of the invention can be manufactured from various materials, including disposable plastics and metals. Also, the retractor can be made of a stainless steel which can be autoclaved and reused. The retractor and expandable structure can be provided in differing dimensions. In one embodiment, the expandable structure is between about 40 mm and 180 mm long and can expand from a closed position of about 4 mm to 8 mm diameter to an expanded dimension of about 24 mm to 32 mm diameter.  
         [0036]     This invention can be embodied in other forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be had to the following claims rather than the foregoing specification as indicating the scope of the invention.