Abstract:
The invention is directed to a medical device, particularly a penile prosthesis, that includes an implantable element and a reservoir. The implantable element is configured to be implanted within the pelvic region of a patient and is designed to be capable of inflation and deflation via fluid transfer to and from the element. The reservoir is coupled to the implantable element. The fluid is drawn from the reservoir for inflation of the implantable element and returned to the reservoir for the deflation. The reservoir is approximately one inch or less in depth. The minimal depth enables the fluid reservoir to be placed in front of the puborectalis muscle and behind the abdominal fascia without being seen on an external view of the patient.

Description:
CLAIM TO PRIORITY  
       [0001]     The present application claims priority to U.S. provisional patent application 60/669,427, filed Apr. 8, 2005 and entitled “Fluid Reservoirs for Penile Implant Devices” and to U.S. provisional patent application 60/669,673, filed Apr. 8, 2005 and entitled “Fluid Reservoirs for Penile Implant Devices”. The noted provisional patent applications are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to surgical implant devices for containing fluid. More particularly, the present invention relates to fluid reservoirs for use with penile implant devices and related methods for implantation of such reservoirs.  
       BACKGROUND OF THE INVENTION  
       [0003]     One common treatment for erectile dysfunction includes the use of a penile implant device. A particular type of penile implant device, commonly known as a three-piece device, includes a pair of inflatable cylindrical prostheses that are implanted into the corpus cavernosae of the penis. The cylindrical prostheses are connected to a fluid-filled reservoir through a pump and valve assembly. Such a pump and valve assembly is typically implanted into the scrotum of the patient, while the reservoir is implanted in the abdomen. Tubing is used to connect each penile prosthesis to the pump, and additional tubing is used to connect the pump to the reservoir. To activate the penile implant device, the patient can typically actuate the pump using one of a variety of methods that cause fluid to be transferred from the reservoir through the pump and into the prostheses. This results in the inflation of the prostheses and produces rigidity for a normal erection. Then, when the patient desires to deflate the prostheses, a valve assembly within the pump in such a manner that the fluid in the prostheses is released back into the reservoir. Additional manipulation of the cylindrical prostheses may also be required. This removal of fluid from the cylindrical prostheses returns the penis to a flaccid state while simultaneously refilling the reservoir with fluid.  
         [0004]     The reservoir used in these three-piece systems is usually in the form of a flexible bag or bladder that can expand and contract in volume with movement of fluid to and from the reservoir. In many cases, the reservoir is relatively spherical in shape, which requires placement of the reservoir in a location in the patient&#39;s body where there is sufficient space to allow the system to operate properly and to keep the reservoir from causing a visible protrusion outside the patient&#39;s body. Thus, spherical reservoirs are often placed below the puborectalis muscle during surgical implantation of the penile implant device, which requires a “blind” approach. This approach can be relatively difficult, particularly for less experienced surgeons. Thus, it is desirable to provide a reservoir that can offer an easier surgical approach for the doctor, such as a surgical procedure that eliminates the requirement to position the reservoir behind the puborectalis muscle.  
       SUMMARY OF THE INVENTION  
       [0005]     The invention relates to devices and methods that overcome certain shortcomings of the prior fluid reservoirs fro penile implant devices. In particular, the invention provides fluid reservoirs with a design that eliminates the requirement for placement below the puborectalis muscle, anterior to the transversalis fascia. Thus, the invention provides fluid reservoirs having sufficiently small depth that enables them to be implanted submuscularly in the lower abdomen where they will be virtually undetectable from outside the patient&#39;s body. In particular, the reservoir length and width are designed and/or chose so that the reservoir can fit in the patient lateral to the midline of the lower abdomen. This location can be relatively easy for the surgeon to reach during implantation of the device, and provides for a less intrusive device implantation than the surgery required for some other reservoirs. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     The invention will be further explained with reference to the appended Figures, wherein like structure is referred to by like numerals through the several views, and wherein:  
         [0007]      FIG. 1  is a top view of a three piece implantable prosthesis device having a pair of penile prostheses, a pump, and a reservoir of the present invention;  
         [0008]      FIG. 2  is a perspective view of the preferred embodiment of the reservoir of the present invention;  
         [0009]      FIG. 3  is a cross-sectional view of the reservoir taken along line  3 - 3  of  FIG. 2 ;  
         [0010]      FIG. 4  is a cross-sectional view of the reservoir taken along line  4 - 4  of  FIG. 3 ;  
         [0011]      FIG. 5  is a cross-sectional view of the reservoir taken along line  5 - 5  of  FIG. 3 ;  
         [0012]      FIG. 6 a  an exploded view of the portion of  FIG. 3  designated by circle  6 .  
         [0013]      FIG. 7  is a perspective view of the reservoir of  FIG. 2  with hidden lines showing the contours of the reservoir;  
         [0014]      FIG. 8  is a side view of the reservoir of  FIG. 2 , showing a reservoir shell attached to a support structure or device of an adapter, and a tube attached to the adapter at a sleeve;  
         [0015]      FIG. 9  is a perspective view of one embodiment of a reservoir of the invention;  
         [0016]      FIG. 10  is a top view of the reservoir of  FIG. 9 ;  
         [0017]      FIG. 11  is a side view of the reservoir of  FIG. 9  as viewed from the neck opening side of the reservoir;  
         [0018]      FIG. 12  is perspective view of another embodiment of a reservoir of the invention;  
         [0019]      FIG. 13  is a top view of the reservoir of  FIG. 12 ;  
         [0020]      FIG. 14  is a side view of the reservoir of  FIG. 12  as viewed from the neck opening side of the reservoir.  
         [0021]      FIG. 15  depicts the reservoir implanted in a patient in a location that is posterior to the puborectalis muscle and anterior to the abdominal fascia.  
     
    
     DETAILED DESCRIPTION  
       [0022]     Referring now to the Figures, wherein the components are labeled with like numerals throughout the several Figures, and initially to  FIG. 1 , the preferred configuration of a surgically implantable penile prosthesis device  10  having a three-piece design is illustrated. As shown, device  10  generally includes first and second inflatable penile cylinders  12  and  14 , respectively, a pump  16 , and a reservoir  18  in accordance with the invention. First penile cylinder  12  is fluidly coupled to pump  16  by a tube  20  and second penile cylinder  14  is fluidly coupled to pump  16  by a tube  22 . Pump  126  is fluidly coupled to reservoir  18  by tube  24 . When device  10  is implanted into a patient, cylinders  12  and  14  are surgically located in the corpus cavernosa regions of a penis and pump  16  is located within the scrotum of a patient, while reservoir  18  is located within the abdominal area of the patient. In user, the patient can activate pump  16  in some manner (e.g., squeezing the body or other portion of pump  16  in a particular way to open the valve) to move fluid from reservoir  18  to inflate penile cylinders  12  and  14  and provide an erection. Similarly, the patient can activate pump  16  in some manner to return fluid to reservoir  18  and thereby deflate penile cylinders  12  and  14  and return the cylinders to a flaccid condition.  
         [0023]     A wide variety of configurations of penile prosthesis devices may utilize a reservoir  18  of the type described here, and any of the alternative reservoirs described herein, wherein device  10  of  FIG. 1  is intended to illustrate only representative system in which a reservoir  18  may be used. For example, a number of different types of pump configurations may be used, such as those that require very little manipulation to move fluid between the reservoir and cylinders, or those that instead require the user to repeatedly squeeze the pump body to cause fluid transfer within the penile prosthesis device or system. In addition, devices having greater or fewer components than the number that are used in a three-piece design can utilize the advantages of the reservoirs of the present invention.  
         [0024]      FIGS. 2 through 8  further illustrate the preferred embodiment of reservoir  18  of the present invention, which generally includes a shell  26  having an interior space  28  and an opening  30  at one end. A neck portion  34  extends from shell  26  at opening  30  for connection with a tube, such as tube  24  of prosthesis device  10 . Neck portion  34  may be directly connected to tube  24  or another component, or an adapter or other device can be used between neck portion  34  and tube  24  to provide a smooth transition between these two components. Any additional devices or adapters that are provided between tube  24  and neck portion  34  may be directly molded to one or both components, or may be adhered or otherwise attached to one or both components to prevent fluid leakage and allow for smooth fluid flow. In any case, the transitions between tube  24  and neck portion  34  should not inhibit the flow of fluid to and from interior space  28  of reservoir  18 .  
         [0025]     Referring particularly to  FIGS. 3 and 4 , reservoir  18  is generally provided in an exemplary flat, elongated shape as illustrated, which includes shell  26  having a length  100 , a width  102 , and a depth or thickness  106 . Reservoir  18  is preferably symmetrical or generally symmetrical about its centerline  130 , shown in  FIG. 4 . Width  102  is preferably relatively constant along at least a portion of length  100  and is more preferably relatively constant along at least half of the length  100  of shell  26 , although it is possible that width is constant along less than half of the length  100  of shell  26 . A straight portion  114  of one edge of shell  26  is located between curved portions  116  and  118 . Curved portion  116 , which is shown on the top edge of shell  26  in  FIG. 4 , has a corresponding mirror image curved portion  116   a  on the opposite or bottom edge of shell  26 . Curved portions  116  and  116   a  provide the outside boundary for a portion of shell  26  that decreases in width from width  102  at straight portions  114  and  114   a  down toward a diameter  104  of neck portion  34 , see also the section provided in  FIG. 5  depicting the diameter  104  of neck portion  34 . The angle of transition from the neck portion  34  to the shell portion  26  is approximately angle A.  FIG. 6  further details the transition area  33  from neck portion  34  to shell  26 . As shown, the transition area  33  is provided with an inner radius B and an outer radius C. Additionally, neck portion  34  is defined by a neck portion length  107  and a transition area length  109   
         [0026]     Curved portion  118 , which is shown on the top edge of shell  26  in  FIG. 4 , is a curved edge that extends from straight portion  114  on one edge of shell  26  to the centerline  130  of shell  26 . Curved portion  118   a  continues from curved portion  118  around the bottom edge of shell  26  and around to the straight portion  114   a  of shell  26 . In this preferred embodiment. length  100  has a greater length than width  102 , and both length  100  and width  102  are greater in length than thickness or depth  106 .  
         [0027]     Referring again to  FIGS. 3 and 4 , the thickness  111  of the wall  113  of the shell  26  can be appreciated. The thickness  111  of the wall  113  smoothly blends to the reduced thickness  115  of the neck portion wall  117 , e.g., from a thickness of 0.040 inches in the shell to a thickness of 0.030 inches in the neck portion. In the preferred embodiment, the thickness  111  of the wall  113  is preferably of a substantially consistent thickness, however, the thickness can vary without departing from the spirit or scope of the invention. The contours of the reservoir may be observed in  FIG. 7 .  
         [0028]     Additional features may be added to the reservoir to maintain the integrity of the shell shape. One example is to provide an internal or external support material that is attached to or otherwise situated relative to the shell. The internal or external support may be a wire, such as may be constructed of nitinol, and may be shaped to generally match the outer shape of the reservoir. The wire or other support may be molded as part of the construction of the reservoir after it is formed. The wire or other support may also extend along the top and/or bottom surfaces of the shell.  
         [0029]     Another feature that can help maintain the shape of the shell is the inclusion of portions that extend along the top and bottom shell surfaces like ribs or corrugations. Such ribs can extend in any desired direction along these surfaces, and can be of varying lengths, depths, and/or widths. One or more such ribs or corrugations can be used, where the ribs on a single shell may be the same or different from each other. The ribs can also be useful in the molding manufacture of the part. That is, although the shell can be made by dipping or molding, the addition of one or more ribs will particulary be beneficial in a molding process. The ribs or corrugations can help direct fluid flow and maintain patency.  
         [0030]     In the preferred embodiment of the invention, length  100  of reservoir  18  is about 3.85 inches (9.78 cm), width  102  is about 2.30 inches (5.84 cm), depth  106  is about 1.00 inches (2.54 cm), and neck diameter  104  is about 0.57 inches (1.45 cm). The angle of transition A is about 44 degrees, the inner radius B of transition area  33  is about 0.235 inches (0.61 cm), the outer radius C of transition area  33  is about 0.229, the neck portion length  107  is about 0.22 inches (0.56 cm), and the transition area length is about 0.22 inches (0.56 cm). In reference to shell thicknesses, thickness  111  of the wall  113  is about 0.40 inches (1.02 cm) while thickness  115  of the neck portion wall  117  is about 0.3 inches (0.76 cm). Reservoir  18  in this preferred embodiment is designed to hold about 85-ml of fluid. However, it is understood that reservoir  18  can be designed to have different dimensions to hold varying capacities of fluid, including capacities of 65-ml and 100-ml, along with other desired volumes. In any case, the depth of a reservoir of the invention, such as depth  106  of reservoir  18 , should be small enough that it can be implanted submuscularly in the lower abdomen of the patient and remain virtually undetectable from outside the patient&#39;s body. Further, the length  100  and width  102  are selected to fit into the patient lateral to the midline of the lower abdomen.  
         [0031]     Referring additionally to  FIG. 1 , tube  24  is shown as having an adapter  36  between neck portion  34  and tube  24 , although tube  24  and adapter  36  are not the only types of devices that can extend from reservoir  18  for fluid communication between reservoir  18  and other adjacent devices or components. For example, additional or different adapters or devices may be connected directly to one end of neck portion  34 , in which case any tubing used may optionally be attached to the configuration at some other point distal from shell  26  and neck portion  34 . In cases where such a tube is used, however, the tube preferably includes an inner fluid passage extending along its length through which fluid can move to and from shell  26 . In one exemplary configuration, tube  24  is a separate component that is sealed to either adapter  36  or neck portion  34  during a molding process as described below. However, tube  24  may be molded as part of the neck portion or otherwise fused or bonded directly to neck portion  34  with an appropriate technique.  
         [0032]     Referring to  FIG. 8 , an exemplary adapter  36  is illustrated with additional detail, which includes a body portion  38  and annular flange  40 . Preferably annular flange  40  increases in diameter from the area of tube  24  toward the end of flange  40 . Body portion  38  also includes an annular groove  42  that is at the end of flange  40 . Body portion  38  also includes an annular groove  42  that is at least partially defined by flange  40  and body portion  38 , as illustrated. The width of groove  42  is preferably designed to accept the free edge of shell  26 . This is, neck portion  34  is designed to fit into annular groove  42 . Flange  40  is preferably flexible enough that it can conform generally to the outside shape of shell  26  in both its expanded and collapsed conditions. Further, when neck portion  34  is positioned within groove  42 , the inside surface of flange  40  may be adhered or otherwise bonded to the outside surface of shell  26  at or adjacent to neck portion  34 . In addition, or alternatively, an outside surface of body portion  38  may be bonded to an inside surface of annular neck portion  34  in order to secure shell  26  to adapter  34 . In addition, the inside surface of flange  40  may also be adhered to a portion of shell  26  beyond neck portion  34 , such as where the diameter of shell  26  increases and beyond the area where neck portion  34  is positioned within annular flange  40 . It is contemplated that the thickness of the neck portion may vary and/or the width of the annular gap may change along its length. For any portions of the reservoir components that are bonded to each other, any medical grade adhesive, insert molded bonding technology or method, or the like may be used.  
         [0033]     When a penile prosthesis device utilizing a reservoir of the invention is implanted in a user, shell  26  may be repeatedly deflated and inflated. During deflation, the shell  26  can collapse inwardly on itself at least slightly, which may also cause it to flex at neck portion  34  (as well as other parts of shell  26 ). Such repeated flexing could cause fatigue at neck portion  34 , which could cause a gradual thinning of the wall and eventual failure (e.g., leakage) between shell  26  and flange  40 . Thus, flange  40  is desirably configured to provide additional support at neck portion  34  while also providing a smooth transition from body portion  38  of adapter  36  to shell  26  and minimizing areas of stress concentration. Adapter  36  may also include a wide variety of other features, such as the support structures or elements designed to minimize or prevent fluid flow blockage caused by the collapse of an attached reservoir, such as the type described in U.S. patent application Ser. No. 10/957,190, entitled “Fluid Reservoirs for Penile Implant Devices and Method of Manufacturing”, which is also commonly owned by the assignee of the present invention, the entire contents of which are hereby incorporated by reference.  
         [0034]     In another aspect of the invention, a lubricity enhancing coating such as a parylene coating or the like may be applied to at least a portion of an inside surface of a reservoir, in U.S. Pat. No. 6,558,315 (Kuyava) and U.S. Patent Application Publication No. 2003/0220540 (Kuyava), both of which are commonly owned by the assignee of the present invention Another example of the use of parylene coatings for artificial sphincters is further described, for example, in U.S. Patent Application Publication No. 2003/0028076 (Kuyava et al), which is also commonly owned by the assignee of the present invention. A parylene coating may be applied by using conventionally known techniques such as vapor deposition or the like, for example. Such a lubricity enhancing coating can improve the frictional characteristics of an inside surface of a reservoir and the durability of the reservoir. This can improve reliability of a reservoir by controlling the frictional effects on an inside surface of a reservoir that can result during inflation and deflation of such reservoirs.  
         [0035]     In another aspect of the invention, at least some of the components of the penile implant devices can be treated on their outer surfaces with an antimicrobial agent, including the cylinders, pump and/or reservoir. Examples of treating antimicrobial agents on implantable medical devices are described, for example, in U.S. Pat. No. 6,534,112 (Bouchier et al) and U.S. Patent Application Publication No. 2004/0040500 (Bouchier et al.) both of which are commonly owned by the assignee of the present invention.  
         [0036]     When the reservoir  18  and optional adapter  36  are constructed of a single piece, the configuration may be formed by injection molding, which can use liquid silicone rubber, for example, or by compression molding, which may use gum rubber or high compression rubber, such as silicone, for example. Methods of injection molding may include the use of a flowable material (e.g., thermoplastic or thermosetting), such as a polymeric material, and a mold. The flowable material is placed at a desired temperature (e.g., by heating) and is injected into a cavity to produce a molded component (here, a fluid reservoir). The mold is then opened, optionally after cooling, and the molded component can be removed from the mold and optionally cured. In particularly preferred embodiments, a reservoir can be prepared by injection molding methods. The reservoir may be molded to become attached to a tube at the exit orifice of the reservoir shell. This is, by preferred injection molding processes, an elongated tube, such as tube  24 , can be attached to the reservoir during a process of injection molding the reservoir. To do this, the tube can be positioned onto a mandrel of a mold. A relatively spherical, solid mold core pin is also included, which a form of the inside of the reservoir. Outer sections of the mold that define the outer surfaces of the reservoir are then placed around the core pin to thereby create a cavity that is the size and shape of the fluid reservoir. The entire mold is then brought to a processing temperature, and then a predetermined amount of a desired material is injected into the mold over the tube and the spherical mode core pin to fill the cavity. After a predetermined time, the mold is opened and the reservoir with the attached tube is removed from the mold, with the sleeve thereby becoming molded around the outside diameter of the tube as the sleeve body portions of the reservoir are formed.  
         [0037]     The reservoir, being of a flexible material ca be removed from around the core pin following cooling or curing of the flexible material as necessary. Removal of the reservoir from the core pin can be done by stretching the reservoir material around the core pin. Optionally, water, soap, air, or a combination of these, can be used to separate the inside surface of the reservoir from the core pin. One especially convenient and effective way to introduce any materials such as water, soap and air, to the space between the core pin and the inside of the reservoir, is to inject any one or more of these through the tube connected to the reservoir. In this method, there is an air poppet included in the shell mold that introduces a burst of air into the shell end opposite of the neck. A plastic fixture or removal tool is placed over the mandrel, which is slightly larger than the shape of the shell, after the silicone has been molded over the mandrel that ‘grabs’ the air-inflated shell. In this way, the fixture with the inflated shell is pulled off the mandrel.  
         [0038]     As one example, a reservoir may be made from liquid silicone rubber, such as a high consistency gum rubber silicone. A mold temperature in the range of 250 deg. F. (121 deg. C.) to 275 deg. F. (135 deg. C.) may be used. Also, a molding time of approximately 2.5 minutes may be used. Alternatively, the reservoir may be made from any other useful, flexible medical or industrial material that is biologically inert and non-reactive with the inflating fluid that will be contained by the reservoir. The material may be a thermoset or thermoplastic. Specific examples of useful materials can include thermosetting silicone rubber (e.g., polydimethyl siloxane), thermosetting or thermoplastic urethanes, C-flex, santoprene thermoplastics, and the like.  
         [0039]      FIG. 14  depicts an example of the reservoir  18  implanted within a patient, tube  24  is also depicted. The pertinent anatomy is identified as follows: (1) transverse abdominis muscle  130 ; (2) internal oblique muscle  132 ; (3) orthotopic bladder  134 ; (4) transversalis fascia  136 ; (5) rectus abdominis muscle  138 ; (6) external oblique muscle  140 ; (7) linea alba  142 ; (8) pubic ramus  144 ; (9) spermatic cord  146 ; (10) external inguinal ring  148 ; (11) pubic tubercle  150 ; and (12) symphysis pubis  152 .  
         [0040]      FIGS. 9 through 11  further illustrate one exemplary embodiment of reservoir  218  of the present invention, which generally includes a shell  226  having an interior space  228  and an opening  230  at one end. A neck portion  234  extends from shell  226  at opening  230  for connection with a tube, such as tube  224  of prosthesis device  210 . Neck portion  234  may be directly connected to tube  224  or another component, or an adapter or other device can be used between neck portion  234  and tube  224  to provide a smooth transition between these two components. Such an adapter may be particularly useful, for example, when the neck portion has a different cross-sectional shape (e.g., elliptical) than the cross-sectional shape (e.g., circular) of the tube to which the neck portion is attached. Any additional devices or adapters that are provided between tube  224  and neck portion  234  may be directly molded to one or both components, or may be adhered or otherwise attached to one or both components to prevent fluid leakage and allow for smooth fluid flow. In any case, the transitions between tube  224  and neck portion  234  should not inhibit the flow of fluid to and from interior space  228  of reservoir  218 .  
         [0041]     Reservoir  218  is generally provided in a relatively flat, circular shape as illustrated, which includes shell  226  that is shaped as a relatively flat disc. Reservoir  218  is preferably symmetrical or generally symmetrical about its centerline  310 , with shell  226  having a diameter  300  and a depth or thickness  302 . Neck portion  234  extends from shell  226  at one end, and is generally oval or elliptical in shape. Neck portion  234  has a width  304  and a depth  312  that is equal to or at least slightly smaller than depth or thickness  302  of shell  226 . In addition, neck portion  234  has a material thickness  306 . The material from which the remainder of reservoir  218  is made may be the same or a different thickness than material thickness  306 . A small curved portion  314  that curves in the opposite direction of the outer periphery of shell  226  can be provided in the transition area between shell  226  and neck portion  234 .  
         [0042]     Shell  226  also includes a slight curvature relative to the neck portion  234  or as compared to a planar device, which is most visible in  FIG. 11 . This curvature has a radius  308  when viewed from the bottom or neck area  234  of shell  226 . The center of a circle that defines the radius  308  would include an axis that extends in the same direction as centerline  310 . Although neck portion  234  is not shown as following the same curvature as shell  226 , it is understood that neck portion  234  may also have a radius that is similar to radius  308  (i.e., neck portion  234  may follow the same curvature as shell  226 ), or neck portion  234  may alternatively have a radius that is smaller or larger than radius  308 .  
         [0043]     Referring particularly to  FIG. 11 , shell  226  includes a top surface  320  and an opposite bottom surface  322  that is spaced from top surface  320  by a distance equal to depth  302 . A curved edge surface  324  extends between top surface  320  and bottom surface  322  along most of the peripheral edge of shell  226 , except in the area of opening  230 . Top surface  320  is preferably a slightly curved surface that is generally parallel to bottom surface  322 , which is a surface that has a similar curve. However, it is possible that these surfaces  320 ,  322  are angled relative to each other such that depth  302  varies within the interior portion of shell  226 . The curved edge surface  324  between top surface  320  and bottom surface  322  can be provided with a material thickness that is greater than the material thickness of either or both of top and bottom surfaces  320 ,  322 . Alternatively, the material thickness of curved edge surface  324  can be less than or the same as the material thickness of top and bottom surfaces  320 ,  322 . In any case, curved edge surface  324  is shaped and sized to promote the integrity of the shape of shell  226 . This feature is particularly advantageous to maintain the shape of reservoir  218  when the reservoir is subjected to external pressures cause by the patient&#39;s internal organs and bodily fluids after it is implanted in the body.  
         [0044]     In one particular exemplary embodiment, diameter  300  of shell  226  is about 3.30 inches (8.38 cm), thickness  102  is about 0.50 inches (1.27 cm) and width  304  of neck portion  234  is about 0.75 inches (1.91 cm). Further, the thickness of top and bottom surfaces  320 ,  322  is about 0.025 inches (0.064 cm) and thickness  306  of neck portion  234  is about 0.025 inches (0.064 cm). The internal volume of reservoir  218  in this embodiment is about 3.63 in 3  (59.49 cm 3 ). However, it is understood that reservoir  218  can be designed to have different wall thickness and overall dimensions to hold varying capacities of fluid, including capacities of 65-ml and 100-ml, along with other desired volumes. In any case, the depth of a reservoir of the invention, such as depth  302  of reservoir  218 , should be small enough that the reservoir can be implanted submuscularly in the lower abdomen of the patient and remain virtually undetectable from outside the patient&#39;s body. The diameter  300  is also selected to fit into the patient lateral to the midline of the lower abdomen. Further, the curvature of shell  226  of this exemplary embodiment has a radius  308  of about 6 inches (15.24 cm); however, radius  308  can be chosen to be any appropriate size that allows placement of shell  226  submuscularly in the lower abdomen.  
         [0045]      FIGS. 12 through 14  further illustrate another exemplary embodiment of reservoir  418  of the present invention, which generally includes a shell  426  having an interior space  428  and an opening  430  at one end. A neck portion  434  extends from shell  426  at opening  430  for connection with a tube, such as tube  24  of prosthesis device  10 . Neck portion  434  may be directly connected to tube  24  or another component in a prosthesis device, or an adapter or other device can be used between neck portion  434  and tube  24  to provide a smooth transition between these two components. Such an adapter may be particularly useful, for example, when the neck portion has a different cross-sectional shape (e.g., elliptical) than the cross-sectional shape (e.g., circular) of the tube to which the neck portion is attached. Any additional devices or adapters that are provided between tube  24  and neck portion  434  may be directly molded to one or both components, or may be adhered or otherwise attached to one or both components to prevent fluid leakage and allow for smooth fluid flow. In any case, the transitions between tube  24  and neck portion  434  should not inhibit the flow of fluid to and from interior space  428  of reservoir  418 .  
         [0046]     Reservoir  418  is generally provided in a relatively flat, oval-like shape as illustrated, which includes shell  426  having a height  450 , a width  452 , and a depth or thickness  454 . Height  450  is shorter than width  452 , thereby creating the non-circular or oval-like shape of shell  426 . Reservoir  418  is preferably symmetrical or generally symmetrical about a centerline  456  that extends from the shell throughout the center of neck portion  434 , as shown in  FIG. 13 . Shell  426  (not including neck portion  434 ) is preferably symmetrical or generally symmetrical about a centerline  458  that is perpendicular to centerline  456 . Neck portion  434  extends from shell  426  at one end, and is generally oval or elliptical in shape. The outer periphery of reservoir  418  includes shell  426  having two curved edge portions  460  and  462 , where edge portion  460  extends from centerline  456  at the top of shell  426  around the left side of shell  426  to neck portion  434 , and edge portion  462  extends from centerline  456  at the top of shell  426  around the right side of shell  426  to neck portion  434 . Curved edge portions  460 ,  462  provide the outside boundary for a portion of shell  426  that decreases in height  450  when moving away from centerline  456 , and which also decreases in width  452  when moving away from centerline  458 . A small curved portion  464  that curves in the opposite direction of the outer periphery of shell  426  can be provided in the transition area between shell  426  and neck portion  434 .  
         [0047]     Neck portion  434  has a width  436  and a depth  438  that is equal to or at least slightly smaller than depth or thickness  454  of shell  426 . In addition, neck portion  434  has a material thickness  440 . The material from which the remainder of reservoir  418  is made may be the same or a different thickness than material thickness  440 .  
         [0048]     Shell  426  also includes a slight curvature relative to the neck portion  434  or as compared to a planar device, which is most visible in  FIG. 14 . This curvature has a radius  442  when viewed from the bottom or neck area  434  of shell  426 . Although neck portion  434  is not shown as following the same curvature as shell  426 , it is understood that neck portion  434  may also have a radius that is similar to radius  442  (i.e., neck portion  434  may follow the same curvature as shell  426 ), or neck portion  434  may alternatively have a radius that is smaller or larger than radius  442 .  
         [0049]     Referring particularly to  FIG. 14 , shell  426  includes a top surface  444  and an opposite bottom surface  446  that is spaced from top surface  444  by a distance equal to depth  454 . A curved edge surface  448  extends between top surface  444  and bottom surface  446  along most of the peripheral edge of shell  426 , except in the area of opening  430 . Top surface  444  is preferably a slightly curved surface that is generally parallel to bottom surface  446 , which is a surface that has a similar curve, although it is possible that these surfaces  444 ,  446  are angled relative to each other such that depth  454  varies within the interior portion of shell  426 . It is also possible that surfaces  444 ,  446  have different curvatures relative to each other or that one of the surfaces is generally straight. Surfaces  444 ,  446  may also curve in opposite directions from each other.  
         [0050]     The curved edge surface  448  between top surface  444  and bottom surface  446  can be provided with a material thickness that is greater than the material thickness of either or both of top and bottom surfaces  444 ,  446 . Alternatively, the material thickness of curved edge surface  448  can be less than or the same as the material thickness of top and bottom surfaces  444 ,  446 . In any case, curved edge surface  248  is shaped and sized to promote the integrity of the shape of shell  426 . This feature is particularly advantageous to maintain the shape of reservoir  418  when the reservoir is subjected to external pressures cause by the patient&#39;s internal organs and bodily fluids after it is implanted in the body. In yet another alternative, the edge surface  448  could be more square or angular in shape, where it is contemplated that the outside surface of edge surface  448  can be more squared than the portion of surface opposite edge surface that faces the inside of the shell, which may be curved, for example.  
         [0051]     In one particular exemplary embodiment of reservoir  418 , width  452  of shell  426  is about 4.50 inches (11.43 cm), height  450  is about 2.50 inches (6.35 cm), depth  454  is about 0.50 inches (1.27 cm), and width  436  of neck portion  434  is about 1.00 inches (2.54 cm). Further, the thickness of top and bottom surfaces  444 ,  446  is about 0.025 inches (0.064 cm) and thickness  440  of neck portion  434  is about 0.025 inches (0.064 cm). The internal volume of reservoir  418  in this embodiment is about 3.80 in 3  (62.27 cm 3 ). However, it is understood that reservoir  418  can be designed to have different dimensions to hold varying capacities of fluid, including capacities of 65-ml and 100-ml, along with other desired volumes. In any case, the depth of a reservoir of the invention, such as depth  454  of reservoir  418 , should be small enough that the reservoir can be implanted submuscularly in the lower abdomen of the patient and remain virtually undetectable from outside the patient&#39;s body. Further, the curvature of shell  426  of this exemplary embodiment has a radius  442  of about 6 inches (15.24 cm); however, radius  442  can be chosen to be any appropriate size that allows placement of shell  426  submuscularly in the lower abdomen.  
         [0052]     The present invention has now been described with reference to several embodiments thereof. The entire disclosure of any patent or patent application identified herein is hereby incorporated by reference. The foregoing detailed description and examples have been give for clarity of understanding only. No unnecessary limitations are to be understood therefrom. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the spirit or scope of the invention. Thus, the scope of the present invention should be limited to the structures described herein, but only by those structures