Abstract:
A surgical support attaches to a surgical table by means of mounting plates and base plates that may communicate through a surgical drape without puncturing the surgical drape. The base plates may be attached to the surgical table by means of a pegboard or by direct clamping of the base plates to a side of the surgical table underneath the surgical drape.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     CROSS REFERENCE TO RELATED APPLICATION 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a surgical support system for supporting a surgical device or patient during surgery and in particular to a support system that can be attached to and adjusted with respect to the operating table from the sterile operating field through a surgical drape. 
     During surgery, a surgical drape may be placed ova the operating table to isolate a sterile operating area and sterile equipment from non-sterile areas and equipment. The surgical drape is typically a disposable, flexible plastic material. 
     For surgical procedures such as a total knee replacement, it is necessary for the patient&#39;s leg to be properly positioned and then held fixed in that position before cuts are made for the removal of the existing joint. For this purpose, a sterile leg support system may be positioned on the sterile side of the surgical drape. 
     Such support systems often compromise the sterile barrier of the surgical drape by going around it to the side or penetrating the surgical drape. Some systems attempt to clamp a support system over top of the sterile barrier, but nearly always penetrate the surgical drape. An adhesive backed covering applied to the sterile drape may be used to minimize the opening formed in the surgical drape when the surgical drape is cut or punctured, but such covering has only limited success in preventing contamination of the sterile field. Substantial adjustment of such patient support fixtures, as may be necessary for proper surgery, often requires the physician to move between the sterile and non-sterile fields jeopardizing the sterility of the sterile field. 
     SUMMARY OF THE INVENTION 
     The present invention provides a t fixture that may be repositioned and fixed with respect to the operating table through the surgical drape without penetration of the surgical drape. This is accomplished generally by mechanically interlocking elements that gently deform the surgical drape while engaging each other. Forces of torsion or shear forces along the plane of the table are resisted by abutting surfaces of the interlocking elements when they are engaged. A very light latching force (for example from a magnet system) prevents inadvertent disengagement of the interlocking elements. 
     Specifically, the present invention generally provides a surgical support system for use with an operating room table having a surface defining a table plane. The surgical support system includes at least one base element fixable with respect to the operating room table to extend along the table plane and to present first mechanical interlock features exposed on a upper surface of the base element away from the table top surface A corresponding mounting element then provides second mechanical interlock features interengagable with the first mechanical interlock features of the base element through a pliable surgical drape material without breech of the surgical drape material, where the interlocking of the first and second mechanical interlock features through the surgical drape block relative movement of the base element and the mounting plate along the table plane while allowing engagement and disengagement of the base element and the mounting element along a direction generally perpendicular to the table plane. Latch components are positioned on the base element and mounting element to releasably retain the base element and mounting element against disengagement of the base element and mounting element along a direction generally perpendicular to the table plane. At least one attachment feature is also provided on the upper surface of the mounting element to retain a surgical device such as a patient support or robot am during surgery. 
     It is thus a feature of at least one embodiment of the invention to provide a surgical support system that interlocks through the sterile drape eliminating the need for the surgeon to move between non-sterile and sterile areas in positioning a patient support. 
     The blocking of relative movement of the base element and mounting plate may be provided by surfaces that abut through the surgical drape along a line substantially perpendicular to the table plane. 
     It is thus a feature of at least one embodiment of the invention to provide a method of stabilizing a support used for compression or traction forces by a simple mechanical abutment which tends to compress rather than tear the surgical drape. 
     The first and second mechanical interlock elements may be inter-engaging pegs and sockets sized to engage through a surgical drape. 
     It is thus a feature of at least one embodiment of the invention to provide a system that allows forces to be spread over many contact areas that each requires only minor distention of the surgical drape. 
     The pegs and sockets provide rounded edges to avoid cutting of the surgical drape. 
     It is thus a feature of at least one embodiment of the invention to reduce force-concentrating surfaces that might tear or thin the surgical drape. 
     The latch components may be opposed magnetically attractable materials mounted in opposition on the base element and mounting element. 
     It is thus a feature of at least one embodiment of the invention to provide a simple releasable mechanism that may work through the separation of the surgical drape. 
     The magnetically attractable materials may be selected from permanent magnet material and ferromagnetic material. 
     It is thus a feature of at least one embodiment of the invention to permit a combination of magnets or magnets and ferromagnetic materials to provide flexible trade-off between cost and attractive force. 
     The base element and mounting element may include at least three abutting surfaces separated by at least one inch to define a plane of contact when the first and second mechanical interlock elements are engaged. 
     It is thus a feature of at least one embodiment of the invention to provide a stable mounting surface resistant to tipping under shear forces. 
     The first and second mechanical interlock elements may block relative twisting of the base element with respect to the mounting element about an axis generally normal to the table plane when the first and second mechanical interlock features are engaged. 
     It is a further feature of at least one embodiment of the invention to provide a mounting surface resistant to torsion about a vertical axis. 
     The mounting element may include an undercut edge for receiving a user&#39;s fingers to lift the mounting edge away from the table. 
     It is thus a feature of at least one embodiment of the invention to allow ready removal and reattachment of the mounting element, for example, by a surgeon having gloved hands. 
     The base element and mounting element and first and second mechanical interlock features may be a metal such as aluminum or stainless steel 
     It is thus a feature of at least one embodiment of the invention to provide a sterilizable material that provides sufficient strength and may readily be fabricated into the necessary interlocking shapes. 
     The surgical support system may further include a table plate fixable with respect to the operating room table and having periodic third mechanical interlock features engageable at periodic locations with fourth mechanical interlock features exposed at a lower surface of the base element toward the table top surface so that the base element may be located at any of the periodic locations to be fixed with respect to the operating room table. 
     It is thus a feature of at least one embodiment of the invention to permit a “pegboard” type arrangement that allows a larger range of repositioning of the mounting elements at regular locations from within the sterile field. 
     The third and fourth mechanical interlock features engage at either of two perpendicular angles about an axis normal to the table plane. 
     It is thus a feature of at least one embodiment of the invention to permit translational and rotational repositioning after the surgical drape is in position. 
     Alternatively, the base element includes a clamp bar to be attached to a clamp of the operating room table to fix the base element with respect to the operating room table. 
     It is thus a feature of at least one embodiment of the invention to provide a simple mechanism for attaching the base elements to the table making use of the standard clamp system available on surgical tables. 
     The attachment feature of the mounting element may be an upwardly extending cylindrical peg. 
     It is thus a feature of at least one embodiment of the invention to provide a mounting element that may be engaged and disengaged in a direction generally perpendicular to the intended compression or traction forces and which allows ready angular adjustment. 
     The surgical support system may further include a patient support fixture releasably attachable to the mounting element. 
     It is thus a feature of at least one embodiment of the invention to provide a patient fixture to be positioned and/or attached within the sterile field during surgery. 
     The support fixture may be a foot stirrup. 
     It is thus a feature of at least one embodiment of the invention to provide a patient fixture suitable for knee surgery and the like. 
     The support fixture may further include a beam pivoting at a first end with respect to at least one mounting element and swinging at a second end across an index surface with respect to at least one mounting element, the second end releasably lockable to the index surface at a plurality of angles. A lockable slide is positioned to be movable along the beam and releasably lockable to the beam at a plurality of positions along the beam and a foot stirrup is attached to the lockable slide for receiving and supporting a human foot therein. 
     It is thus a feature of at least one embodiment of the invention to provide a patient fixture suitable for knee surgery that allows multiple dimensions of adjustment from within the sterile field. 
     The foot stirrup may be pivotably attached to the lockable slide about an axis generally perpendicular to an extent of the beam. 
     It is thus a feature of at least one embodiment of the invention to accommodate different extensions of the patient&#39;s leg while preserving natural ankle position. 
     These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is an exploded perspective view of an operating room table fit with a “pegboard” holding multiple base plates that may engage through a surgical drape with mounting plates attached to a patient support fixture; 
         FIG. 2  is a fragmentary exploded perspective view of a support rail of the patient fixture as may be connected to an attachment feature on a mounting plate and showing the mounting plate positioned opposite a base plate with which it engages through a surgical drape; 
         FIG. 3  is a cross-sectional view along lines  3 - 3  of  FIG. 2  showing inter-engaging mechanical elements of pegs and sockets that may operate through the surgical drape between the mounting plate and the base plate and the engagement of downwardly extending cylindrical knobs of the base plate engaging with holes in the pegboard; 
         FIG. 4  is a cross-sectional view perpendicular to that of  FIG. 3  of the support beam as attached to the mounting plate and showing undercuts for removal of the mounting plate; 
         FIG. 5  is a perspective view in partial phantom of a more sophisticated patient support fixture as attached to two mounting plates such as provide for an angulation and extension adjustment; 
         FIG. 6  is a fragmentary side elevational view of the patient&#39;s foot in a foot stirrup of the fixture of  FIG. 5 : 
         FIG. 7  is a perspective view of an alternative assembly of base plates to a patient table not requiring the pegboard of  FIG. 1  but attached directly to universal side rails of the patient table; 
         FIGS. 8   a  and  8   b  are fragmentary cross-sections of a mounting slide for the foot stirrup of  FIG. 6  that automatically locks to a pivot element of the foot stirrup when the foot stirrup is attached to the mounting slide; and 
         FIG. 9  is a figure similar to that of  FIG. 1  showing the mounting plates assembled over a surgical drape and used for mounting an arbitrary surgical device such as a robot arm. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIG. 1 , a surgical support system  10  may work in conjunction with a standard surgery table  12  of the type providing a generally horizontal table top surface  14  supported on a pedestal  16  with respect to the floor surface  18  or the like. The surgery table  12  may include universal side mounting rails  20  the type generally understood in the art having positionable clamps  22  located on either side of the table top surface  14 . 
     Generally the clamps  22  are positioned slightly below the table top surface  14  to receive vertically extending clamp bars  24  of clamp fixtures  26  or the like. The clamps  22  may be tightened to retain the clamp bars  24  in a desired position with respect to vertical height and longitudinal location along the side of the table top surface  14 . 
     In a first embodiment of the invention, clamp fixtures  26  are positioned and adjusted to attach a “pegboard”  30  to overlie all or a portion of the table top surface  14 . Generally the pegboard  30  may be a molded or machined rigid plastic material, for example, approximately ¾ of an inch thick. A set of holes  32  of approximately 1 inch in diameter may be spaced periodically at intersections in a rectilinear grid oriented diagonally with respect to a longitudinal axis  34  of the surgery table  12 . 
     One or more base plates  36  may be installed on top of the pegboard  30  and retained there by downwardly extending cylindrical knobs  66  (shown in  FIG. 3 ) that fit within corresponding holes  32 . In a preferred embodiment, the base plates  36  are generally rectangular plates 3½ inches by 8 inches and about one quarter inch thick and constructed of a metal such as aluminum or stainless steel machined or otherwise formed as is understood in the art. The invention also contemplates manufacture of these elements from reinforced thermoplastic materials. Generally, the pattern of downwardly extending cylindrical knobs  66  in the base plate  36  and holes  32  in the pegboard  30  allows the base plates  36  to be placed in either of two perpendicular positions, either with a longest extent of the base plate  36  aligned with longitudinal axis  34  or perpendicular to a longitudinal axis  34  along the transverse axis, and allows the base plates  36  to be moved incrementally longitudinally or transversely by the periodicity of the holes  32  or approximately 3 inches along each grid axis. 
     A surgical drape  40  may be placed over the table top surface  14  and pegboard  30  with its attached base plates  36 . The surgical drape  40  is generally a water-impervious flexible plastic sheet (for example polyethylene) 1-10 mils in thickness and may include a water-absorbent upper layer. Mounting plates  42  having similar dimension to base plates  36  may then be attached to the base plates  36  through the surgical drape  40  without perforation of the surgical drape  40  as will be discussed below. 
     A cylindrical attachment pin  44  extends upward from the center of the mounting plate  42  to allow the mounting plate  42  to attach to a patient fixture  45 , in this case, the patient fixture  45  providing a foot stirrup  46  mounted on a rail  48 , the latter of which may attach to two of the mounting plates  42  with each mounting plate  42  extending transversely. 
     Referring now to  FIG. 2 , the rail  48  may include a series of regularly spaced vertical bores  50  separated along its length and each sized to receive the cylindrical attachment pin  44  extending up from the mounting plate  42 . The cylindrical attachment pin  44  may be slightly conical so as to provide a wedge fit with the bores  50  when the two are pressed together. 
     Referring also to  FIG. 3 , the upper surface of the mounting plate  42  may otherwise be substantially planar of similar dimensions to the base plate  36  to provide a surface against which the bottom of the rail  48  may stably rest. The lower surface of the mounting plate  42  may provide for a set of downwardly extending pegs  54  that may be received within corresponding upwardly open blinded sockets  56  in the upper surface of the base plate  36 . In one embodiment, four pegs  54  and four corresponding sockets  56  are placed in the corners of each of the mounting plate  42  and base plate  36 , respectively, and three pegs  54  and sockets  56  are placed along a center of its longest axis of each of the mounting plate  42  and base plates  36 , respectively. 
     The size of the pegs  54  is slightly smaller than the sockets  56  so as to accommodate the thickness of the surgical drape  40  therebetween without substantial distention or tearing of the surgical drape  40 . Abutment of the sidewalks of the pegs  54  and sockets  56  substantially resist shear movement  58  of the mounting plate  42  with respect to the base plate  36  along the plane of the table top surface  14 , as resisted by the inter-engaging of the substantially vertical walls of the pegs  54  and sockets  56  through the surgical drape  40 . Similarly, the mounting plate  42  resists torsion about a vertical axis  60 , for example, through cylindrical attachment pin  44  by inter-engaging of these substantially vertical walls. In one embodiment a total of seven pegs  54  and seven sockets  56  will be engaged with at least three of the inter-engaging pegs  54  and sockets  56  separated by more than one inch from each of the others along the plane of the table top surface  14 . 
     The pegs  54  may be substantially cylindrical with rounded bases to avoid sharp edges that might cut or tear the surgical drape  40 . Generally the pegs  54  will have a height of approximately one-quarter inch equal to the corresponding height of the sockets  56 . In an alternative embodiment (not depicted), the pegs  54  may be radially asymmetric, having polygonal or T cross-sections that serve to resist torsion about the vertical axis  60  with or without other adjacent pegs  54 . In this case, the sockets  56  conform in outline to the cross-sections of the pegs  54 . 
     Outside the region of the pegs  54  and sockets  56 , the mounting plate  42  and base plate  36  abut over substantially planar surfaces of greater than four square inches. The mounting plate  42  and base plate  36  may be formed of a cast or machined metal such as aluminum or stainless steel or molded from a rigid thermoplastic material. 
     The mounting plate  42  and base plate  36  may be retained together about the surgical drape  40  against disengaging resilience of the surgical drape  40  and/or any slight upward jarring on the mounting plate  42  by means of magnetic attraction between magnetically attractive materials  62  inset in the lower surface of the base plate  36  across from magnetically attractive materials  64  inset into the upper surface of the base plate  36 . These magnetically attractive materials  62  and  64  may be each permanent magnets oriented to have opposed, and hence attracting, north and south poles or one permanent magnet and one ferromagnetic material such as a steel or iron plate. It will be appreciated that the force of magnetic attraction needs to serve only to preserve engagement of the mounting plate  42  and base plate  36  against relatively minor forces and needs not to resist substantial shear forces  58  or torsional forces necessary for traction or compression which are handled by mechanical inter-engagement of the pegs  54  and sockets  56 . 
     Referring still to  FIG. 3 , the lower surface of the base plate  36  base provides substantially larger cylindrical knobs  66  received within holes  32  in the pegboard  30  which may resist accidental disengagement simply by their greater height (approximately ¾ of an inch) of engagement as well as a slight downwardly narrowing conical to the cylindrical knobs  66  which serve to wedge them into the holes  32  by interference fit. 
     It will be appreciated that the abutting planar surface of the mounting plate  42  and the base plate  36  surrounding the interlocking features of the pegs  54  and sockets  56  provide primary supporting contact surface on alternate sides of the surgical drape  40 . These surfaces serve to capture the drape material peripherally around the interlocking features preventing movement in the drape material, from inducing stress on the drape material at the engagement site of the interlocking features. 
     Referring now to  FIG. 4 , transverse edges  68  of the mounting plate  42  may include undercut portions  70  that may receive a user&#39;s fingers to help pry the mounting plate  42  away from the base plate  36  (not shown in  FIG. 4 ) without tearing or gouging of the surgical drape  40 . 
     It will be appreciated that the elements of the mounting plate  42  may be alternatively manufactured from other materials such as stainless steel, aluminum, titanium, or carbon fiber composites that can withstand high-temperature environments in the sterilization process. 
     It will be further appreciated that in an alternative embodiment, the pegs  54  may be sized to be received directly by holes  32  in the pegboard  30  to allow greater flexibility in the positioning or repositioning of the mounting plates  42  during surgery. In this case magnetically attractive material  64  may be regularly embedded in the pegboard  30 , for example, steel discs or the like. 
     Referring now to  FIG. 5 , two mounting plates  42  may be placed on the surgical drape  40  to support a rail  48  at its opposite ends, the rail  48  extending generally along the longitudinal axis  34 . It will be understood that base plates  36  have been placed beneath the surgical drape  40  to support the mounting plates  42  as required. An elongated swing arm  76  may be attached to a superior end of the rail  48  at a vertical pivot  78  so that the opposite end of the swing arm  76  may slide along a radiused index surface  80  to multiple different angular positions each aligned with an upwardly extending index hole  82  in the index surface  80 . The angular range of sliding will typically be greater than 20 degrees and may be, for example, 24 degrees. A pin  84  passing vertically through the movable end of the swing arm  76  to be received by an index hole  82  may fix the swing arm  76  at any of a variety of different angular positions. A slide  86  fits over the swing arm  76  to slide to a variety of different positions along the swing arm  76  and then lock in any of those positions by lock arm  90 . 
     Referring also to  FIG. 6 , a foot stirrup  92  may be pivotally attached to the top of the slide  86  through horizontal pivot  94  that may also be locked as will be described below. The foot stirrup  92  includes a sole plate  96  supporting a sole of a patient&#39;s foot  98  and a calf support  100  supporting the patient&#39;s calf. It will be appreciated that by adjustment of the angle of the swing arm  76 , the position of the slide  86  on the swing arm  76 , and the angle of the foot stirrup  92 , adjustment of the patient&#39;s leg may be had in these three different dimensions for proper angulation the hip and the knee joint. For this purpose, pivot point  78  may be positioned to be close to the patient&#39;s hip joint 
     Referring now to  FIG. 7 , in an alternative embodiment, base plates  36 , for example, appropriate for the support of the patient fixture  45  shown in  FIG. 5  may be attached directly to clamp bars  24  to be received by clamps  22  without the need for the pegboard  30  while also preserving the segregation between the mounting plates  42  on the sterile side of the surgical drape  40  and the base plates  36  on the non-sterile side. 
     Referring now to  FIGS. 8   a  and  8   b  the slide  86  may have an upwardly opening transverse notch  102  that may receive the horizontal pivot  94  of the foot stirrup  92  (shown in  FIGS. 5 and 6 ). Lock arm  91  provides a cam surface  104  that raises the locking lever  91  as the pivot  94  passes downward into the notch  102  when the foot stirrup is engaged with the slide  86  as shown in  FIG. 8   a . Referring to  FIG. 8   b , when the horizontal pivot  94  is fully seated at the bottom of the notch  102 , the cam surface  104  no longer contacts the pivot  94  and the lock arm  91  drops so that a protruding portion  106  of the cam surface  104  blocks upward movement of the horizontal pivot  94  until the lock arm is manually raised in this way, the surgeon can easily install the foot stirrup  92  single-handedly with it automatically locking in position yet still able to pivot. 
     Referring now to  FIG. 9 , it will be appreciated that the present fixturing system may be used for a variety of surgical accessories not limited to patient positioning elements. For example, a surgical device  108  such as a surgical robot arm or the like may be attached to the rail  48  to allow it to be placed in close proximity to the patient yet at a known location accurately fixed with respect, for example, to the underlying pegboard  30  (shown in  FIG. 1 ) or otherwise positioned mounting plates  36  (such as shown in  FIG. 7 ). By employing the system of the present invention, the surgical device  108  may be rapidly repositioned, for example, on a second rail  48  to a known location with respect to its first position to take advantage previous effort in precisely locating the patient as stabilized on the table possibly by other implementations of the present invention. The surgical device  108  may be located and fixed to particular locations on the rail  48 , determined, for example, by bores  50  (shown in  FIG. 2 ) and/or may employ the rail  48  as an additional movement axis or indexing device through the use of an appropriate drive mechanism engaging the rail  48  or the like. 
     Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
     When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications, are hereby incorporated herein by reference in their entireties.