Patent Application
20130338793
1. Technical Field
The present invention relates generally to the field of prosthetic devices. More particularly, the present invention is directed to a sealing member capable of providing an improved seal for maintaining a vacuum in a vacuum suspension system used for attaching a prosthetic leg to an amputee's residual stump.
2. Description of Prior Art
Prosthetic devices have been a boon to persons who have lost limbs, either to disease or through traumatic injury. Though prosthetic limbs do not replace all of the functionality of the lost limb, they allow the wearer to accomplish much, if not all, of the tasks associated with a natural limb.
Prosthetic limb technology has evolved over time, from extremely simple devices to highly sophisticated devices. With regard to prosthetic legs, one recent development has been the vacuum suspension system.
A vacuum suspension system works with a prosthetic device that is comprised of a socket and a prosthetic leg. The socket is an attachment member which provides an interface between the wearer's residual stump and the prosthetic leg. It is typically a rigid container having an open top end and an interior, whereby the stump is placed into the interior of the socket through the open top end. The bottom exterior of the socket comprises mechanisms to attach the prosthetic leg. There are typically one or more liners used with the socket, to protect the stump and to increase the comfort level to the wearer when the socket is being worn. The efficiency of a socket is dictated by the integrity of the fit between the stump and the socket; a socket that fits securely, with a minimum of movement between the stump and socket, will allow the wearer to most effectively use the prosthetic leg. However, where the fit between the stump and the socket becomes loose or otherwise unstable, the wearer is unable to use the prosthetic leg to its fullest capabilities, resulting in difficulty in ambulating, increased fatigue, increased danger of falls, decreased comfort, and increased risk of injury to the stump.
In a vacuum suspension system, the vacuum suspension component consists of a vacuum pump that pumps air out of the socket when it is being worn, creating a vacuum. The vacuum secures the stump in place within the socket. An airtight socket is critical for success with vacuum suspension systems. In order to create the vacuum, a special rubberized stump liner is used. The stump liner is placed over the stump before the stump is placed into the socket. During use, the upper portion of the stump liner extends above the top of the socket while the lower portion resides within the interior of the socket. The stump liner is trapped between the stump and the top edge of the socket, creating a lower seal. Any air between the stump liner and the interior surface of the socket is evacuated by the vacuum pump, creating the vacuum that secures the socket to the stump. An external socket sleeve is also used, placed over the top part of the socket and the portion of the stump located outside of the socket, such that the socket sleeve covers the top edge of the socket. The top portion of the stump liner is rolled down such that the top portion of the socket sleeve makes contact with the inner part of the top portion of the stump liner. This contact creates a second seal. An example of a vacuum suspension system is the LimbLogic® VS, made by the Ohio Willow Wood Company.
However, through normal use, leaks develop allowing air to escape the socket, thereby breaking the vacuum. Once the vacuum is broken the integrity of the fit of the socket is compromised. To account for this, vacuum suspension systems also incorporate sensors which continuously monitor the level of the vacuum. As soon as a decrease in the level of the vacuum below a preset level is detected, the vacuum pump is activated and restores the vacuum to the proper level. The wearer may adjust the preset vacuum level for comfort and performance.
While vacuum suspension systems have caused prosthetic legs to become far more useful to the wearer, greatly improving the range of functionality of the prosthetic leg, current systems have their drawbacks. The primary drawback of any vacuum suspension system is the inability of the socket to maintain a constant appropriate level of vacuum during use. Because of frequent leakage, the vacuum pump must run on a relatively constant basis. This severely limits the time that the prosthetic device can be used before the pump's power supply (typically a rechargeable battery) is depleted. This also presents some degree of danger, if the power supply for the pump becomes depleted while the wearer is in a location where replacement or recharging is not practical. In such situations the prosthetic leg may be rendered useless. Even when there is ample power, the constant operation of the pump causes an annoying noise as well as fluctuating pressures on the stump.
Another undesirable consequence of insufficient vacuum integrity is increased wear and tear on the stump liner. Each time the socket leaks and the vacuum is broken, the fit of the socket on the stump becomes looser and the socket moves relative to the stump. Even slight movements cause frictional rubbing between the top edge of the socket and the stump liner. If the stump liner becomes cut or torn from such rubbing it will no longer hold a seal and will need to be replaced. Stump liners typically have a useful life of only a few weeks.
Yet another undesirable consequence of insufficient vacuum integrity is increased trauma to the stump. Movement of the socket relative to the stump due to loss of vacuum irritates the skin. Itching and excess sweat may result. In severe cases the hairs of the stump may be rubbed off or become ingrown, sores may develop, or the stump may become too tender to bear a socket.
It is evident that there is a need for an improved sealing member for vacuum suspension systems.
It is therefore an object of the present invention to provide an improved sealing member for vacuum suspension systems.
It is another object of the present invention to provide an improved sealing member for vacuum suspension systems that reduces the incidence of leakage, thereby maintaining the vacuum at desired levels for greater lengths of time.
It is yet another object of the present invention to provide an improved sealing member for vacuum suspension systems that allows for extended battery life for the vacuum pump.
It is yet another object of the present invention to provide an improved sealing member for vacuum suspension systems that reduces the incidence of stump liner cuts.
It is yet another object of the present invention to provide an improved sealing member for vacuum suspension systems that reduces the trauma to the stump caused by the socket, thereby improving stump health.
Other objects of the present invention will be readily apparent from the description that follows.
The present invention comprises an improved sealing member for a vacuum suspension prosthetic device, whereby the sealing member is placed along the top edge of the socket opening. The sealing member is designed to protect the stump liner from the sharp rigid top edge of the socket. It is also designed to provide a more efficient seal between the socket and the stump liner, thereby improving the ability of the vacuum suspension prosthetic device to maintain a vacuum. The sealing member is made of a pliable, nonfriable material, thereby being somewhat deformable when pressed against by the residual stump. This property of the sealing member allows a small amount of “give” during movement, thereby preventing gapping that could otherwise occur and cause leaks, though still providing a firm region of contact to maintain stability and control during use. Moreover, the sealing member does not present a sharp rigid surface to the stump liner, thereby minimizing tearing or cutting of the stump liner. The sealing member may be integrated with the top edge of the socket or affixed thereto.
The present invention also discloses methods for retrofitting a socket with the improved sealing member. This may be accomplished by placing a pre-formed sealing member over the top edge of a socket. It may also be accomplished by applying layers of resilient material to the top edge of the socket to build up a sealing member.
Other features and advantages of the present invention are described below.
The present invention discloses an improved sealing member 10 to be used with a vacuum suspension prosthetic device. The vacuum suspension prosthetic device has the following components: a socket 20, a stump liner 30, a socket sleeve 35, a vacuum pump 40 with a vacuum level sensor 42, and a prosthetic leg 50. See
The stump liner 30 is used in conjunction with the socket 20 and is placed over the residual stump 60. It is a flexible sleeve having an open top end and a closed bottom end, and fits snugly over the residual stump 60. It is substantially air impermeable. When placed over the residual stump 60 and then placed into the socket 20, the stump liner 30 presses against the inner surface 24 of the socket 20. See
The socket sleeve 35 is placed over the socket 20 and over the stump 60. It is a flexible sleeve having open top and bottom ends and fits snugly over the socket 20. It is substantially air impermeable. After the residual stump 60 and stump liner 30 are placed into the socket 20, the top portion of the socket sleeve 35 is rolled up against the top portion of the stump liner 30 that extends out of the socket 20 and which is folded down. See
The vacuum pump 40 is a device capable of evacuating air from the interior space 29 of the socket 20 to create at least a partial vacuum therein. It is in communication with the interior space 29 of the socket 20, typically through an air valve 44. The vacuum level sensor 42 is in communication with the interior space 29 of the socket 20. It is capable of ascertaining the vacuum level within the interior space 29 of the socket 20. It is also in communication with the vacuum pump 40. Depending on the vacuum level ascertained by the vacuum level sensor 42, operation of the vacuum pump 40 is either engaged to increase or reestablish at least a partial vacuum within the socket 20 or rendered inoperable because an appropriate vacuum level is present.
The sealing member 10 of the present invention is constructed of a pliable material. The material should be nonfriable, resilient, and durable. In some embodiments the material comprising the sealing member 10 may have a liquid state and a solid state. An example of such a material is synthetic rubber, such as Performix® Brand Plasti Dip®. Other materials may also be used, such as closed cell foam and natural rubber.
The sealing member 10 should have a substantially uniform height and a substantially uniform thickness. It has a top side 12, an outer lateral side 14, and an inner lateral side 16. It is substantially rounded or curved where its top side 12 transitions to its inner lateral side 16, thereby avoiding any hard edges on its inner side 16.
The sealing member 10 is located along the top edge 28 of the socket 20. See
In one embodiment the sealing member 10 is pre-formed. See
In another embodiment the sealing member 10 is formed onto the socket 20. In this embodiment the sealing member 10 is made of a material having a liquid state and a solid state. The sealing member 10 is applied to the top edge 28 of the socket 20 while the material is in its liquid state and then allowed to harden into its solid state. This process may be repeated multiple times to build up the height and width of the sealing member 10. In variants of this embodiment the sealing member 10 is applied to a portion of the outer surface 25 of the side wall 22 of the socket 20 adjacent to the top edge 28 of the socket 20 while the material is in its liquid state and then allowed to harden into its solid state. In other variants the sealing member 10 is applied to a portion of the inner surface 24 of the side wall 22 of the socket 20 adjacent to the top edge 28 of the socket 20 while the material is in its liquid state and then allowed to harden into its solid state. As before, either or both of these processes may be repeated multiple times to build up the height and width of the sealing member 10.
The present invention also contemplates a method for retrofitting a socket 20 used in a vacuum suspension system. The method comprises the steps of:
A. obtaining a material having a liquid state and a solid state;
B. applying the material to the top edge 28 of the socket 20 while the material is in its liquid state; and
C. allowing the material to harden into its solid state.
In this embodiment the sealing member 10 is made of a material having a liquid state and a solid state. An example of such a material is synthetic rubber, such as Performix® Brand Plasti Dip®. This process may be repeated multiple times to build up the height and width of the sealing member 10.
A variation of this method includes the following additional steps:
B1. applying the material to a portion of the outer surface 25 of the side wall 22 of the socket 20 adjacent to the top edge 28 of the socket 20 while the material is in its liquid state; and
B2. applying the material to a portion of the inner surface 24 of the side wall 22 of the socket 20 adjacent to the top edge 28 of the socket 20 while the material is in its liquid state.
Steps B1 and B2 may be performed in any order after step A and before step C.
These steps allow for the sealing member 10 to better adhere to the socket 20.
Another variation of this method includes the following additional step:
A1. preparing the socket 20 to receive the material by sanding the top edge 28 of the socket 20.
Step A1 may be performed at any time before step B. Sanding is understood to mean not only the roughening of the surface of the top edge 28 of the socket 20 by the use of sand paper, but also a roughening of the surface of the top edge 28 of the socket 20 by the use of and suitable means, such as a wire brush or file.
Alternatively, the following steps may also be performed in conjunction with Step A1:
A2. preparing the socket 20 to receive the material by sanding the portion of the outer surface 25 of the side wall 22 of the socket 20 adjacent to the top edge 28 of the socket 20; and
A3. preparing the socket 20 to receive the material by sanding the portion of the inner surface 24 of the side wall 22 of the socket 20 adjacent to the top edge 28 of the socket 20.
Steps A1, A2, and A3 may be performed in any order and at any time before steps B, B1, B2, and C.
In another embodiment of the method for retrofitting a socket 20 used in a vacuum suspension system, the method comprises the steps of:
A. obtaining a pre-formed sealing member 10; and
B. placing the sealing member 10 onto the top edge 28 of the socket 20.
The pre-formed sealing member 10 is configured as a substantially continuous ring, having a channel formed between its outer lateral side 14 and its inner lateral side 16. See
A variation of this method includes the following additional step:
A1. placing an adhesive onto the top edge 28 of the socket 20.
Step A1 is performed before step B.
The adhesive may be any suitable adhesive capable of bonding rubberized and plastic materials.
Modifications and variations can be made to the disclosed embodiments of the sealing member 10 without departing from the subject or spirit of the invention as defined in the following claims.
