Abstract:
An apparatus suitable for cleaning a surgically prepared working surface comprises a body portion adapted to supply pressurized fluid (preferably carbon dioxide gas) to the surgically prepared working surface and aspirate surface debris dislodged from the surgically prepared working surface. The apparatus further comprises a head portion adapted to constrain the supplied pressurized fluid to flow substantially along the surgically prepared working surface to dislodge debris there from when the head portion is in contact with the surgically prepared working surface. The dislodged surface debris are aspirated by the body portion.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to surgical instruments, and more particularly to apparatus and method for cleaning a surgically prepared working surface.  
         [0003]     2. Description of the Related Art  
         [0004]     In traditional orthopedic surgery, bone is prepared to receive a prosthetic implant by first cutting or sculpting the bone with a manual or powered tool such as a saw, drill, or broach. Next, the exposed bone is usually cleaned with a sterile saline solution for lavage and irrigation. Finally, suction is applied to remove debris. Often, surgical sponges are inserted into a cavity or against the bone surface to absorb excess fluids.  
         [0005]     Joint replacements are commonly but not necessarily secured with the aid of “joint cement” or biocompatible adhesives. A typical such cement is a polymethyl methacrylate. The success of such adhesives is thought to depend in part on proper preparation of the bone bed.  
         [0006]     U.S. Pat. No. 5,037,437 to Matsen III (1991) discloses a significant improvement in the art of preparing bone surface for cemented joint replacement surgery. Matsen identified some of the previously unrecognized shortcomings of traditional liquid flushing lavage for preparation of the cancellous portions of an exposed bone bed. Matsen&#39;s invention was based on the finding that dry flowing gas directed at and into the sculpted bony bed effectively prepares the bone for prosthetic implantation. When a bone cement is also used, the use of gas increases the likelihood of strong mechanical interdigitation of the bone cement with the bone. A number of such advantages to the gas lavage technique are identified in U.S. Pat. No. 5,037,437; the enumerated advantages need not be repeated here. Additional advantages may exist which have not been identified. Matsen also suggests that carbon dioxide is especially well suited for use as the dry gas for bone lavage, being demonstrated safe for use in the human body. As he notes, “the very high diffusion coefficient of carbon dioxide causes it to present a significantly lower risk of embolism as compared to the use of nitrogen or oxygen.” Moreover, carbon dioxide gas is commonly available in hospital operating rooms, finding use in laparascopic surgery, for example.  
         [0007]     Since the publication of the Matsen patent, tools have become available for preparing bony surfaces by sterile, dry gas lavage, or lavage with sterile admixtures of gas and liquid. A carbon dioxide lavage system is available, for example, from Kinamed, Inc. in Camarillo, Calif. (marketed under the trade name “CarboJet”). The use of carbon dioxide is believed to be more effective than liquid debris removal because a compressed gas jet creates strong, fluctuating pressure gradients, displacing debris rapidly and thoroughly. This method is more effective at removing fluid and fluid-suspended debris from the interstices of cancellous bone.  
         [0008]     Although surgical gas lavage nozzles are available, typical nozzles must be used in concert with surgical suction tools. Simultaneous manipulation and coordination of both gas supply and suction is difficult. Flow of the gas is not well controlled or confined to the bony surface. Both suction and gas jet must be constantly moved in a drying pattern to effectively clean and dry the bony surface. The difficulty of this technique in increased in surgical situations that permit only limited access or interfere with the surgeon&#39;s freedom of motion. As one example, in knee replacement surgery several planar bone cuts are commonly made in the femur and tibia. It is desirable to prepare these surfaces to receive prosthetics.  
         [0009]     Many surgeons are currently employing a “minimally invasive” surgical technique for knee replacement, which involves making only a very small incision at the front of the knee. The very small incision does not permit full freedom to access the cut bone surfaces from any arbitrary angle. In fact, a gap of less than 12 millimeters may be accessible between the prepared femur and tibia surfaces. In some cases, a gap as small as 8 millimeters may be present. Conventional gas jet instruments and suction instruments are not well suited to access the planar cuts in the knee without more exposure than that offered in minimally invasive surgical techniques.  
         [0010]     A need persists for specially adapted lavage devices and methods which can better access bony surfaces, and which more efficiently and conveniently prepare the surfaces to receive cement or implants. Any time saved in the operating room is of great value (medically and economically) to both surgeon and patient.  
       SUMMARY OF THE INVENTION  
       [0011]     In accordance with one aspect of the invention, an apparatus suitable for cleaning a surgically prepared working surface comprises means for supplying pressurized fluid to the surgically prepared working surface, at least one surface debris aspirator operatively coupled to the pressurized fluid supply means, and means for constraining the supplied pressurized fluid to flow substantially along the surgically prepared working surface. The constrained fluid flow forcibly cleans the surgically prepared working surface of biological fluids and debris.  
         [0012]     In accordance with another aspect of the invention, an apparatus suitable for cleaning a surgically prepared working surface comprises means for supplying pressurized fluid to the surgically prepared working surface, at least one surface debris aspirator operatively coupled to the pressurized fluid supply means, and means for constraining the supplied pressurized fluid to flow substantially tangentially relative to the surgically prepared working surface. The tangential fluid flow forcibly cleans the surgically prepared working surface of biological fluids and debris.  
         [0013]     In accordance with yet another aspect of the invention, an apparatus suitable for cleaning a surgically prepared working surface comprises a body portion adapted to supply pressurized fluid to the surgically prepared working surface and aspirate surface debris dislodged from the surgically prepared working surface. The apparatus further comprises a head portion adapted to confine the supplied pressurized fluid to flow substantially along the surgically prepared working surface to dislodge debris there from when the head portion is in contact with the surgically prepared working surface. The dislodged surface debris are aspirated by the body portion.  
         [0014]     In accordance with still another aspect of the invention, an apparatus suitable for cleaning a surgically prepared working surface comprises a body portion adapted to supply pressurized fluid to the surgically prepared working surface and aspirate surface debris dislodged from the surgically prepared working surface. The apparatus further comprises a head portion adapted to constrain the supplied pressurized fluid to flow substantially tangentially relative to the surgically prepared working surface to dislodge debris there from when the head portion is in contact with the surgically prepared working surface. The dislodged surface debris are aspirated by the body portion.  
         [0015]     In accordance with a further aspect of the invention, a method for cleaning a surgically prepared working surface comprises supplying pressurized fluid to the surgically prepared working surface, providing at least one surface debris aspirator, constraining the supplied pressurized fluid to flow substantially along the surgically prepared working surface, and using the constrained fluid flow to forcibly clean the surgically prepared working surface of biological fluids and debris.  
         [0016]     In accordance with a still further aspect of the invention, a method for cleaning a surgically prepared working surface comprises supplying pressurized fluid to the surgically prepared working surface, providing at least one surface debris aspirator, constraining the supplied pressurized fluid to flow substantially tangentially relative to the surgically prepared working surface, and using the constrained tangential fluid flow to forcibly clean the surgically prepared working surface of biological fluids and debris.  
         [0017]     In accordance with another aspect of the invention, an apparatus for cleaning a surgically prepared bone surface comprises a pressurized fluid supply channel; an aspiration channel; and a cleaning head, including at least one chamber, in communication with said aspiration channel and said fluid supply channel. The chamber has an orifice, the boundary of said orifice defining a boundary surface capable of close engagement with the prepared bone surface to substantially close said chamber. The chamber is arranged to create an internal pressure gradient between said pressurized fluid supply channel and said aspiration channel, with a path for fluid flow from the fluid supply channel to the aspiration channel. The fluid flow path for fluid flow includes at least one region in which flow is constrained to flow along the boundary surface.  
         [0018]     In accordance with another aspect of the invention, an apparatus for cleaning a surgically prepared bone surface comprises a body portion adapted to supply fluid to the surgically prepared surface and to aspirate surface debris dislodged from the surgically prepared working surface; and a head portion having an orifice adapted to engage the surgically prepared bone surface. The body portion has a length dimension in a lengthwise direction, and the orifice is directed sidewards, in transverse relation to the lengthwise direction of the body portion.  
         [0019]     These and other aspects of the invention will become apparent from a review of the accompanying drawings and the following detailed description of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     The present invention is generally shown by way of reference to the accompanying drawings in which:  
         [0021]      FIG. 1  is a front perspective view of an apparatus suitable for cleaning a surgically prepared working surface in accordance with the present invention;  
         [0022]      FIG. 1A  is an enlarged partial front perspective view of the apparatus of  FIG. 1 ;  
         [0023]      FIG. 2  is a side perspective view of the apparatus of  FIG. 1  being used to clean a surgically prepared working surface in accordance with the present invention;  
         [0024]      FIG. 3  schematically shows an exemplary embodiment of the present invention; and  
         [0025]      FIG. 4  is a cross-sectional view taken along the sectioning plane  4 - 4  of  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]     Some embodiments of the invention will be described in detail with reference to the related drawings of  FIGS. 1-4 . Additional embodiments, features and/or advantages of the invention will become apparent from the ensuing description or may be learned by practicing the invention.  
         [0027]     In the figures, the drawings are not to scale with like numerals referring to like features throughout both the drawings and the description.  
         [0028]     The following description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention.  
         [0029]      FIG. 1  is a front perspective view of an apparatus or tool generally referred to by reference numeral  10 , adapted for cleaning a surgically prepared working surface in accordance with the present invention. The embodiment of  FIG. 1  is particularly well adapted for cleaning a substantially planar bony surface, such as is produced by an oscillating saw in preparation for implantation of a knee prosthesis.  
         [0030]     The tool  10  includes an elongated body having a sidewards facing orifice  12 , situated near the forward end of the body. (“Sidewards” is intended to convey that the orifice faces in a direction generally across or transverse to the long axis or dimension of the body). The forward end of the body, including the orifice, will also be referred to as the “head portion” of the tool  10  The tool preferably has hose couplings, preferably disposed near the rearward end of the tool: a pressurized gas hose connection  14  and a vacuum hose connection  16 . Optionally, these connections could be integrated into a trigger type control grip (not shown) which facilitates control of the application/disconnection of both gas and suction, via a simple trigger operated valve. However controlled, gas is controllably supplied under pressure from pressurized gas supply  18  to gas connection  14  via a hose  20 . Similarly, suction is controllably supplied from vacuum source  22  via hose  24  to the vacuum hose connection  16 .  
         [0031]     The head portion  13  of tool  10  is more clearly seen in (magnified)  FIG. 1A . Head  13  has an orifice  12  which is preferably bounded by a lip or rim  26 . In the embodiment shown, the rim forms a generally square perimeter around the orifice  12 . The orifice  12  opens into an internal cavity  26  having a forward chamber  28  and a rearward chamber  30 , which are incompletely divided by an internal partition  34 . At least one hidden, internal gas channels  36  and  38  connect the rearward chamber to the vacuum hose coupling  24 , and thus allow the rearward chamber (vacuum chamber)  30  to communicate with the vacuum supply  22 . Similarly, internal pressurized gas channel  40  connects the forward chamber  28  to the pressurized gas connection  14 , allowing the forward chamber to communicate with the pressurized gas supply  18 .  
         [0032]     Forward chamber has an internal barrier  42  which is breached by a wide slot as shown. Optionally, a series of small gas directing holes could be provided to disperse the gas flow into a curtain. Such features tend to spread and direct the gas flow into a ribbon of flowing gas. Further details of the gas flow are discussed below in connection with  FIG. 3 .  
         [0033]     As shown in  FIG. 1A , the partition  34  does not extend completely to the plane defined by the rim  26 ; rather, the partition terminates in a shoulder  46  A small clearance exists between the shoulder  26  and the plane of the rim  26 , defining a relatively narrow slot through which gas can flow from the forward chamber to the rearward chamber (thus from pressure toward vacuum).  
         [0034]     The entire tool  10  can suitably be machined or otherwise formed from a solid such as aluminum or stainless steel, which are capable of enduring repeated autoclaving for sterilization. Alternatively, polymers or other materials could be used. In some embodiments the tool may be disposable, thereby avoiding the need for sterilization by the hospital.  
         [0035]      FIG. 2  shows how the tool can be used to prepare the bony surfaces of a knee to receive a prosthetic replacement. As shown, the bone is previously prepared by cutting with a saw to produce at least one substantially planar cut surface  50 . The tool is inserted through an incision, which need not be large, and manipulated to engage the rim  26  with the planar cut, bony surface  50 . A close fit is desirable, but some leakage is tolerable. Having the head of the tool engaged with the bony surface  50 , the surgeon activates the sources of pressurized gas and suction, and moves the tool in a pattern to clean the bony surface. When the surface is clean (and dry), the surgeon removes the tool and applies the cement in accordance with medical practice. It is recommended that the tool be manipulated from the far side to the near side of the surface, so that debris and blood is pulled from far to near in a scraping motion.  
         [0036]      FIG. 3  shows the direction of gas flow when the device is activated in engagement with a bony surface. The bony surface can be visualized as surface  52 , but here is imagined to be transparent so as to better visualize the gas flow in the tool. The extent of the rim or other boundary of the orifice defines a boundary surface for the orifice. The figure assumes that the orifice is fully engaged with bony surface  52 , by placing with slight pressure the rim  26  flush to the planar bone surface  52 . Thus engaged, boundary surface to bony surface, the cavity and bone surface together define a substantially enclosed volume or chamber having a pressurized gas source at one end and a vacuum at the other end, incompletely separated by partition  34 . More generally described, the apparatus thus engaged defines a substantially closed volume having on at least one side a bony surface. Due to the pressurized gas source and the vacuum source, the volume has a pressure gradient substantially across the bony surface. The fluid is thus constrained to flow substantially across the surgically prepared surface  52 . Most preferably, in at least some region the gradient is substantially tangential to the surface to be cleaned. The fluid is constrained to flow tangentially to the surface to be cleaned, at least in some region.  
         [0037]     In a preferred embodiment, the partition  34  constricts or pinches the gas flow, visualized by flow arrows  54  in the figure. Flow between the partition  34  and the bony surface is pinched or constricted as the gas passes through the narrow clearance between partition and bone. Thus, across the narrow sill of partition  34  the flow has increased velocity and decreased pressure due to “Bernoulli&#39;s principle” or “venturi effect”. Applicants speculate that the lowered pressure and increased velocity in this pinched channel is efficacious to draw debris and liquid (such as blood) from the interstices of a porous bony surface, which effect is observed to occur with unexpected efficiency.  
         [0038]     Gas flow is also visualized in  FIG. 4 . As the cross section shows, pressurized gas supplied from a source flows forward through an internal channel  40  in the cleaning tool  10  to the forward chamber  28 . Simultaneously, suction is applied from vacuum source, which communicated via another internal channel  36  with rearward chamber  30 . Due to the pressure gradient, gas flows from the forward chamber to the rearward chamber. However, the complete cavity (comprising forward and rearward chambers  28  and  30 ) is substantially closed when the orifice is flush against a bony surface, so the gas is constrained to flow through the relatively narrow slot between the lower sill of partition  34  and the top of the bony surface  50 . In passing across this lip, the flow accelerates and the pressure drops, drawing fluid and debris off of the surface. Gas, liquid, and debris then flow into the rearward (vacuum) chamber and exit the tool through the vacuum channel, which is preferably large enough to accommodate debris without clogging. The entire cleaning process occurs within a closed volume defined by the combination of the cavity and bony surface in close fitted relationship. In addition to increasing the cleaning efficiency, the closed system also reduces splattering and controls the aerosolization of biological materials (such as blood, fat and marrow).  
         [0039]     Although a planar geometry is shown for the orifice, other geometries could be employed for cleaning other surfaces. For example, hemispherical geometries (such as found in socket joints) could be cleaned by a tool with a suitably curved surface, provided that the orifice engage the bony surface to effectively confine the flow and encourage flow across the surface, in a direction generally tangential thereto. Furthermore, cylindrical or conical geometries could be employed to clean bone channels (such as a broached femoral canal).  
         [0040]     Note that in the embodiment shown in the figures the tool  10  has a thickness dimension d which is relatively thin in relation to its length L (indicated in  FIG. 1 ). In some embodiments, the thickness d should preferably be less than 12 millimeters, to allow insertion through a relatively small incision. into the interstices of a (prepared) knee joint. More preferably the thickness should be 8 millimeters or less, to service knee joints in a minimally invasive surgical technique. Note also that in the embodiment shown, the orifice or aperture  12  is side facing in relation to the long axis of the tool  10  and the gas and vacuum supply channels included therein. This allows easy access to surfaces having their normal disposed at substantially right angles to the long axis of the tool. This arrangement is advantageous because it considers the geometry of common cutting tools such as either circular or oscillating saws. Such saws cut planes disposed parallel to the plane of the saw&#39;s motion. The side facing orifice  12  is conveniently disposed to clean the surfaces produced by such cuts  
         [0041]     The inventors presently believe that the preferred pressurized gas for use in the invention is carbon dioxide (CO 2 ). Some of the reasons for this conclusion are set forth in the Matsen patent, referenced above in the “Background of the Invention”. However, the invention could be modified to employ other pressurized gases, or an admixture of liquid and gas. In order to take full advantage of the “Bernoulli effect” in passing through the constricted channel, a compressible fluid such as a gas or gas mixture is greatly preferred.  
         [0042]     A person skilled in the art would undoubtedly recognize that other components and/or configurations may be utilized in the above-described embodiments. Moreover, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.  
         [0043]     While the invention has been described in detail with regards to several embodiments, it should be appreciated that various modifications and/or variations may be made in the invention without departing from the scope or spirit of the invention. In this regard it is important to note that practicing the invention is not limited to the applications described hereinabove. Many other applications and/or alterations may be utilized provided that such other applications and/or alterations do not depart from the intended purpose of the invention. For example, the head, orifice, and rim may be shaped to fit contours other than planar surfaces. Admixtures of gas and liquid may be used in place of a carbon dioxide gas. Various control valves and pressure regulation apparatus may be added to the cleaning head or to it&#39;s supply lines. The body may comprise primarily gas and suction lines. The cleaning head may have multiple pressure chambers and/or multiple vacuum chambers; the head could be arranged with suction forward and pressure situated rearward; pressure could be provided in a middle chamber, with gas flowing to two or more suction orifices (one forward, one rear); the pressure could be provided in a middle chamber with suction divided between right and left chambers, causing dual cleaning jets (right and left). Other such variations could be devised. A skirt can be added to or substituted for the rim around the cleaning orifice. A flexible or conformable skirt could be used.  
         [0044]     Also, features illustrated or described as part of one embodiment can be used in another embodiment to provide yet another embodiment such that the features are not limited to the exemplary embodiments described hereinabove. Thus, it is intended that the invention cover all such embodiments and variations as long as such embodiments and variations come within the scope of the appended claims and their equivalents.