Abstract:
A prosthetic limb socket assembly includes a bleeder valve configured to automatically adjust vacuum pressure within the prosthetic limb socket based upon a difference in ambient air pressure and vacuum pressure within the prosthetic limb socket. The bleeder valve includes: a housing having a first end, a second end, and channel extending therethrough providing fluid communication between the ambient and the interior of the prosthetic limb socket; and a valve disc disposed within the channel and biased into a substantially sealed engagement with a valve seat, wherein a certain pressure difference between the ambient and the interior of the prosthetic limb socket is operative to overcome the bias and unseat the valve disc from the valve seat.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The current disclosure claims the benefit of U.S. Provisional Application, Ser. No. 61/552,976, filed Oct. 28, 2011, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present disclosure generally pertains to systems for releasably coupling a prosthetic device, such as a prosthetic limb socket assembly, to a residual limb of an amputee. 
         [0003]    The present disclosure contemplates that in some circumstances it may be desirable to apply a vacuum to a socket of a prosthetic limb to assist maintaining a patient&#39;s residual limb within the socket. Among other potential benefits, applying a vacuum to a socket may assist in retaining the socket on a wearer&#39;s residual limb and/or may reduce volume loss in the residual limb. As used herein, “vacuum” may refer to pressures less than atmospheric pressure. A vacuum may be applied to a socket by withdrawing some of the air within the socket using a vacuum pump, for example. 
       SUMMARY 
       [0004]    Embodiments of the current disclosure include a bleeder valve assembly that may be incorporated into an elevated vacuum locking system of a prosthetic limb assembly. Use of such a bleeder valve system may improve retention and comfort for a prosthetic limb assembly that includes a stump-receiving socket. 
         [0005]    According to an embodiment, a prosthetic limb socket assembly includes a valve configured to automatically adjust vacuum pressure within the prosthetic limb socket based upon a difference in ambient air pressure and vacuum pressure within the prosthetic limb socket. In a more detailed embodiment, the valve comprises a bleeder valve. In a further detailed embodiment, the bleeder valve includes: a housing having a first end, a second end, and channel extending therethrough providing fluid communication between the ambient and the interior of the prosthetic limb socket; a valve disc disposed within the channel and biased into a substantially sealed engagement with a valve seat, where a certain pressure difference between the ambient and the interior of the prosthetic limb socket is operative to overcome the bias and unseat the valve disc from the valve seat. In a further detailed embodiment, the bias is manually adjustable. Alternatively, or in addition, the bias is provided by a spring positioned within the channel between the valve disc and a spring seat, where a spring seat may be threadedly received within the channel so that rotating of the spring seat moves the spring seat towards or away from the valve disc, depending upon direction of rotation of the spring seat, thereby respectively compressing or decompressing the spring. 
         [0006]    According to an embodiment, a bleeder valve assembly for use with a prosthetic limb socket assembly, includes: a housing having a first end, a second end, and an interior channel, the housing being adapted to be mounted to a prosthetic limb socket assembly such that the interior channel provides fluid communication between the ambient and an interior of a prosthetic limb socket; a spring seat positioned approximate the first end of the interior channel; a valve seat positioned approximate the second end of the interior channel; a valve disc positioned adjacent the valve seat; and a spring positioned between the valve disc and the spring seat, biasing the valve disc into sealed contact with the valve seat, thereby sealing the interior channel; where a certain pressure difference between the ambient and the interior of the prosthetic limb socket is operative to overcome the bias of the spring and unseat the valve disc from the valve seat. In a more detailed embodiment, the spring seat is axially adjustable to allow for adjustment of the bias applied by the spring. In a further detailed embodiment, the spring seat is threadedly mounted with respect to the interior channel. The housing may be barrel shaped. The bleeder valve may include a first fitting disposed on the first end of the housing, where the first fitting includes a nipple and a seal between the first fitting and the housing. And the bleeder valve may further include a second fitting disposed on the second end of the housing and a seal disposed between the second fitting and the housing. The valve disc may include a resilient stopper; and the valve disc may include a conical portion coaxial with the axis of the interior channel and tapering inwardly towards the first end. 
         [0007]    An embodiment is directed to a method for regulating vacuum pressure within a prosthetic limb socket assembly including a step of automatically adjusting vacuum pressure within the prosthetic limb socket based upon a difference in ambient air pressure and vacuum pressure within the prosthetic limb socket. In a more detailed embodiment the adjusting step is performed by a valve assembly mounted to the prosthetic limb socket, where the valve assembly provides fluid communication between the prosthetic limb socket interior and the ambient when in an unsealed orientation. In a further detailed embodiment, the valve assembly is a bleeder valve assembly. In a further detailed embodiment, the bleeder valve includes: a housing having a first end, a second end, and channel extending therethrough providing fluid communication between the ambient and the prosthetic limb socket interior; and a valve disc disposed within the channel and biased into a substantially sealed engagement with a valve seat, where a certain pressure difference between the ambient and the interior of the prosthetic limb socket is operative to overcome the bias and unseat the valve disc from the valve seat. In a further detailed embodiment, the bias is manually adjustable, and the method may further include a step of manually adjusting the bias. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an exploded perspective view of an example bleeder valve assembly  100  according to at least certain aspects of the present disclosure; 
           [0009]      FIG. 2  is a partial cutaway perspective view of an example bleeder valve assembly  100  according to at least some aspects of the present disclosure; 
           [0010]      FIG. 3  is an elevational side view of an exemplary front fitting and o-ring seal according to an embodiment; and 
           [0011]      FIG. 4  is an elevational side view of an exemplary back fitting and o-ring seal according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Some example bleeder valve assemblies according to the present disclosure may be configured to be fluidicly coupled to an interior volume of a socket comprising an elevated vacuum locking system. For example, some example bleeder valve assemblies may be arranged to limit the vacuum that may be applied to a socket, such as by allowing air to enter the socket when the difference in pressure between the socket and an ambient atmosphere exceeds a predetermined set point. 
         [0013]      FIG. 1  is an exploded perspective view of an example bleeder valve assembly  100  according to at least certain aspects of the present disclosure. Bleeder valve assembly  100  may include a housing comprised of a generally tubular barrel  10 , which may include a first end  12  and a second end  14 . In some example embodiments, first end  12  and/or second end  14  may be internally threaded. Barrel  10  may at least partially define an interior  16 . 
         [0014]    A generally cylindrical, externally threaded set screw  20  may be installed into interior  16  of barrel  10 , such as threading via first end  12 . Set screw  20  may include an axial through passage  22 , which may allow air flow longitudinally through set screw  20 . 
         [0015]    First end  12  of barrel  10  may couple with a front fitting  30 , such as by an externally threaded section  32  of front fitting  30  threadedly engaging internally threaded first end  12  of barrel  10 . Front fitting  30  may include externally threaded section  32 , a body  34  (which may have a generally hexagonal cross section), and/or a nipple  36 . Front fitting  30  may include an axial through passage  38 , which may extend through nipple  36 , body  34 , and externally threaded section  32 . As illustrated in  FIG. 3 , some example embodiments may include a seal, such as an o-ring  34 A, which may provide a substantially sealed (e.g., substantially air tight) interface between front fitting  30  and barrel  10  when assembled. In some example embodiments, o-ring  34 A may be disposed between externally threaded section  32  and body  34 . 
         [0016]    Returning to  FIG. 1 , a bias, such as helical coil compression spring  40 , may be disposed in interior  16  of barrel  10 , such as via second end  14  of barrel  10 . When installed, a first end  42  of spring  40  may be arranged to press against set screw  20  and/or front fitting  30 . 
         [0017]    A valve disc, such as resilient (e.g., rubber) stopper  50 , may be disposed in interior  16  of barrel  10 , such as via second end  14  of barrel  10 . A first end  52  of stopper  50  may be arranged to press against a second end  44  of spring  44 . In some example embodiments, a second end  54  of stopper  50  may be generally conically tapered and/or may include a projection. 
         [0018]    Second end  14  of barrel  10  may couple with a back fitting  60  (providing seal seat as discussed below), such as by an externally threaded section  62  of back fitting threadedly engaging internally threaded second end  14  of barrel  10 . Back fitting  60  may include externally threaded section  62  and a body  64 , which may have a generally hexagonal cross section. Back fitting  60  may include an axial through passage  68  (see  FIG. 2 ), which may extend through body  64  and externally threaded section  32 . Through passage  68  may open into a seat  66 , which may be disposed within interior  16  of barrel  10  when assembled. Seat  66  may be shaped to releasably seal with second end  54  of stopper  50 . For example, seat  66  may be inwardly generally conically tapered and/or may include a conical seating surface. Spring  40  may be arranged to bias stopper  50  against back fitting  60 , such that the engagement between stopper  50  and back fitting  60  may be substantially air-tight. As illustrated in  FIG. 4 , some example embodiments may include a seal, such as an o-ring  64 A, which may provide a substantially sealed (e.g., substantially air tight) interface between back fitting  60  and barrel  10  when assembled. In some example embodiments, o-ring  64 A may be disposed between externally threaded section  62  and body  64 . 
         [0019]      FIG. 2  is a partial cutaway perspective view of an example bleeder valve assembly  100  according to at least some aspects of the present disclosure. When bleeder valve assembly  100  is assembled, set screw  20 , spring  40 , and/or stopper  50  may be disposed substantially entirely within interior  16  of barrel  10 . Front fitting  30  and back fitting  60  may be disposed at first end  12  and second end  14  of barrel  10 , respectively. Through passage  38  of front fitting  30  and through passage  22  of set screw  20  may be fluidicly connected such that interior  16  of barrel  10  may be fluidicly connected to nipple  36  of front fitting  30 . Through passage  68  of back fitting  60  may be fluidicly connected to the ambient atmosphere. 
         [0020]    In some example embodiments, a difference in pressure between ambient and nipple  36  (specifically through passage  38 ) may actuate bleeder valve assembly  100 . Ambient pressure may act on stopper  50  via through passage  68  in back fitting  60 . In particular, ambient pressure may oppose the force applied by spring  40  on stopper  50 . In some example embodiments, the force applied by spring  40  on stopper  50  may tend to seat stopper  50  into a sealed engagement with back fitting  60  and/or the force of the ambient pressure on stopper  50  may tend to unseat stopper  50  from back fitting  60 . 
         [0021]    In some example embodiments, the force applied to stopper  50  by the ambient pressure may depend on the pressure difference between ambient pressure and a pressure in interior  16  of barrel  10 , which is fluidicly connected to nipple  36 . When the force applied to stopper  50  by the ambient pressure exceeds the force applied to stopper  50  by spring  40 , stopper  50  may unseat from back fitting  60 , thereby allowing airflow through bleeder valve assembly  100 . When the force applied to stopper  50  by the ambient pressure is less than the force applied to stopper  50  by spring  40 , stopper may seat against back fitting  60 , thereby preventing airflow through bleeder valve assembly  100 . 
         [0022]    In some example embodiments, nipple  36  may be fluidicly coupled to an interior  204  of a socket  202  of a prosthetic limb  200 , such as via a conduit  70 . A vacuum may be applied to interior  204  of socket  202 , which may aid in retaining socket  202  on a wearer&#39;s residual limb  206 . 
         [0023]    In some example embodiments, a bleeder valve assembly  100  may be arranged to prevent application of excessive vacuum to interior  204  of socket. For example, with nipple  36  fluidicly coupled to interior  204  of socket  202  by conduit  70 , bleeder valve assembly  100  may be actuated based substantially upon a difference between ambient pressure and a pressure in interior  204  of socket  202 . When this difference in pressure exceeds a predetermined set point, bleeder valve assembly may allow ambient air to enter interior  204  of socket  202 . 
         [0024]    In some example embodiments, a set point of a bleeder valve assembly may be adjusted and/or selected. For example, the force applied by spring  40  to stopper  50  may be adjusted by inwardly and/or outwardly threading set screw  20  in interior  16  of barrel in the directions generally indicated by arrow  18 . In some example embodiments, spring  40  may be selected to provide a desired force on stopper  50 . For example, a particular spring  40  having a desired spring constant may be selected from among a plurality of available springs having different spring constants. In some example embodiments, a spring  40  having a desired spring constant may be installed and the set point may be adjusted by varying the position of set screw  20 . 
         [0025]    As used herein, “set point” may refer to a pressure value or a pressure range at which bleeder valve assembly may actuate. For example, some embodiments according to the present disclosure may be provided in three configurations, each of which is associated with actuation at a different predetermined pressure range, such as 20-15 in Hg, 15-10 in Hg, and/or 10-5 in Hg. A prosthetist may determine the most appropriate pressure range for a particular patient and may select an appropriately configured bleeder valve assembly. 
         [0026]    The present disclosure may be related to, and hereby incorporates by reference the following U.S. Patent documents: U.S. Provisional Patent Application No. 61/131,457, filed Jun. 9, 2008; U.S. Pat. No. 7,927,377, issued Apr. 19, 2011; U.S. patent application Ser. No. 12/897,807, filed Oct. 5, 2010; U.S. patent application Ser. No. 13/088,612, filed Apr. 18, 2011; and U.S. patent application Ser. No. 13/088,640, filed Apr. 18, 2011. 
         [0027]    While example embodiments have been set forth above for the purpose of disclosure, modifications of the disclosed embodiments as well as other embodiments thereof may occur to those skilled in the art. Accordingly, it is to be understood that the disclosure is not limited to the above precise embodiments and that changes may be made without departing from the scope. Likewise, it is to be understood that it is not necessary to meet any or all of the stated advantages or objects disclosed herein to fall within the scope of the disclosure, since inherent and/or unforeseen advantages may exist even though they may not have been explicitly discussed herein.