Abstract:
An attachment system secures a residual limb to an artificial limb in a comfortable and substantially non-rotational manner. The attachment system offers proximal anchoring of the residual limb in a hard socket, by connecting a side surface of a residual limb liner to the side surface of the socket. Preferably, this connection is accomplished using an extension member extending from the liner through a portion of the socket interior, through the socket wall, and attaching to a latch mechanism. The preferred attachment system requires no clearance in the bottom of the socket well because neither the extension member nor the latch mechanism is located between the distal end of the residual limb/liner and the bottom of the well. The attachment system is preferably disposed entirely along the side of the limb and the side of the socket.

Description:
[0001]    This application is a continuation of U.S. Non Provisional patent Ser. No. 12/247,179, filed Oct. 7, 2008, patented on Dec. 14, 2010 as U.S. Pat. No. 7,850,739, which is a continuation of Ser. No. 11/234,063, filed on Sep. 23, 2005, entitled “Attachment System for Prosthesis,” issued Oct. 7, 2008 as U.S. Pat. No. 7,431,738, which is a continuation-in-part, and claims priority, of U.S. Non-Provisional patent application Ser. No. 10/746,208, filed on Dec. 23, 2003, entitled “Attachment System for Prosthesis,” issued Jul. 18, 2006 as U.S. Pat. No. 7,077,868, which is a continuation-in-part, and claims priority, of U.S. Non-Provisional patent application Ser. No. 09/972,729, filed on Oct. 4, 2001, entitled “Attachment System for Prosthesis,” issued Dec. 23, 2003 as U.S. Pat. No. 6,666,894, which claims priority of U.S. Provisional Patent Application Ser. No. 60/238,301, filed on Oct. 4, 2000, entitled “Attachment System for Prosthesis,” the disclosures of which are incorporated herein by this reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to prosthetics, and, more specifically to an attachment system used in the donning/doffing of a socket onto a residual limb. The present invention more particularly relates to an attachment system that requires little or no clearance inside the socket between the socket and the residual limb, that controls rotation of the prosthesis, and that may be used with a suction-fit socket system. The invented attachment system extends from the side of a liner on the user&#39;s limb, through an aperture in the socket, to the outer side of the socket, substantially proximal on the limb and on the socket relative to conventional more “distal” attachment devices. Therefore, the invented attachment may properly be called an exterior, proximal attachment device for a prosthesis. 
         [0004]    2. Related Art 
         [0005]    For years, many different methods have been used to retain or “suspend” a prosthetic limb on an amputee&#39;s residual limb. Gravitational and other forces, for example, from movement of the limbs, tend to cause separation between the prosthetic limb and the patient&#39;s residual limb during use. This happens, for example, during the swing phase of gait, when a prosthetic leg is additionally subjected to centrifugal forces. Patients have routinely worn a variety of belts, straps, cuffs, and harnesses to retain their prosthetic limb against separation from the residual limb during these periods. However, such devices are often inconvenient and may tend to cause chafing against the patient&#39;s body, giving rise to sores and abrasions. 
         [0006]    The manner in which a prosthetic limb is suspended and/or attached to the residual limb determines the amount of control an amputee has over the prosthesis. Therefore, by improving suspension/attachment without adding weight and excessive mechanism, the amputee may obtain improved comfort, convenience, and suspension mobility. 
         [0007]    A common approach to tackling this problem has led to the design of a roll-on suction liner, which is rolled onto the residual limb and attached at its distal end to a socket or artificial limb. The liner, which is usually fabricated from silicone, or some other gel form, fits snugly over the residual limb, preferably completely covering the distal end of the residual limb and extending for at least several inches to cover the entire circumference of the proximal region of the residual limb. The liner, in turn, is enveloped, especially at its distal end, by the socket of the prosthesis, which is also called a “hard socket.” A suction fit is preferably formed between the hard socket and the liner. This suspension method is very advantageous for the amputee. It gives the amputee the ability to better control the prosthesis and provides for useful sensory or proprioceptive feedback. Suction suspension also makes a prosthesis feel lighter, compared to other forms of suspension. Unfortunately, only a small percentage of amputees can successfully and comfortably wear a liner without another form of suspension. Therefore, the socket liner is typically equipped with a detachable component, at its distal end, which mates with a locking device in the interior of the socket at the bottom of the interior space or “well.” This system secures the distal end of the residual limb/liner to the distal end of the artificial limb socket well, and, hence, is called a “distal attachment.” The locking device in the distal end of the socket well typically employs a spring-loaded clutch mechanism or a pin-lock mechanism. The component on the distal end of the liner is typically a cylindrical barb-shaped structure or frictionally-retained pin. 
         [0008]    One problem associated with such designs is the tugging or pull on the distal end of the limb. Most of these locks are not air tight, thus allowing air to flow into the hard socket and to eliminate the “suction.” When this happens, the only suspension is the pin, which is a traction suspension, rather than a suction suspension. In cases where prosthetic socks are worn outside the liner, there is a risk the user&#39;s limb will become trapped in the socket if the sock is caught in the locking device. In these incidents, most patients are forced to make emergency trips to their practitioner to remove the prosthetic. Also, the locking device and attachment component cooperate in such a way to permit the barb or pin to lock in a plurality of longitudinal positions, which affects the overall length of the prosthesis. This can make it difficult for the patient to consistently achieve the same prosthetic configuration when the residual limb and the artificial limb are articulated. It should be further noted that, by weight of the lock being added at the distal end of the residual limb or near the distal end of the socket, this can make the prosthetic device feel heavier because of a “lever arm” effect, than if the same weight were placed more proximally. Additionally, many amputees, whether because of the length of their residual limb or their height, do not have room in the suction liner-socket-prosthesis combination for a distal locking mechanism. Or, additionally, use of a distal lock may limit what other prosthetic components that patient may use. 
         [0009]    Despite the large number of suspension options available, none of the above-mentioned devices act to eliminate rotation between the hard socket and the suction liner. In an attempt to alleviate the rotation problem, a design called a “quad socket” has been used for many years. The quad socket is shaped in a square manner more than a cylindrical manner, and forcing the “cylindrical” limb to fit tightly in this square receptacle makes the prosthesis less apt to rotate on the limb, much as if you made a wheel square. Unfortunately, this is not a very comfortable position for the limb. Today, there has been a trend toward more naturally-shaped sockets, making rotation control even more difficult. 
         [0010]    Therefore, there is still a need for an improved attachment system for prosthetics. Also, there is a need for improving retention of the stump in the socket without sacrificing the patient&#39;s comfort and without comprising on expense, weight and simplicity of use of the prosthesis. There also is a need for improving rotation control, which will improve the patient&#39;s overall comfort and agility. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention is an attachment system and methods for connecting a prosthesis to a residual limb of the user. Preferably, the attachment system extends from the side surface of a liner on a residual limb to the outside side surface of a hard socket fitted around the liner and limb. Preferably, the attachment system includes a strap system that connects to the outer side surface of the liner to the socket, wherein said strap extends into the socket along a portion of the limb, and through an aperture in the sidewall of the socket. Preferably, the strap further extends to a buckle or other latch mechanism connected to the socket, typically about midway or more, proximally, on the outside surface of the socket. At least a portion of the buckle or other latch mechanism may be at the outside surface of the socket and accessible to the strap. In some embodiments, an externally mounted buckle may be easily reached and maintained by the user, and easily retrofit as an add-on feature to existing hard sockets. In some embodiments, an internally mounting the buckle/latch mechanism may lower its profile, increasing the ease with which the strap connects to the buckle/latch mechanism, as well as being more aesthetically pleasing. In this way, a combination of the invented prosthetic attachment system and suction fit provide superior retention of the artificial limb on the user. 
         [0012]    The preferred strap system includes a disk member or “umbrella” that may be adhesively secured to the surface of the liner, and an elongated strap that extends distally from the umbrella and longitudinally a short distance along the side surface of the limb. The strap may be secured to the umbrella in such a way that its exact angle relative to the limb&#39;s longitudinal axis may be adjusted as desired and then locked in place, for example, by tightening of a bolt. The lock is preferably a buckle-style latch mechanism, with a spring-biased member and one or more sharp edges, that frictionally engage transverse detents located between transverse raised ridges on the strap&#39;s surface. Thus, the strap is inserted into the buckle to the extent desired by the user, and, in a ratchet-like action, the sharp edge wedges into the transverse detents and secures the strap from being pulled out or away from the buckle. Thus, the strap is anchored in the buckle, and the socket is held closely on the residual limb until the user chooses to unbuckle the buckle. 
         [0013]    The especially preferred embodiment includes a dual strap and buckle system wherein one strap and one buckle are located on the medial surface of the liner and socket respectively and one strap and one buckle are located on the lateral surface of the liner and socket respectively. The especially preferred embodiment also includes the invented strap and buckle system wherein said strap may have a “nipple” shaped tab extension at its most distal end to facilitate the strap through the buckle. The underside of the said strap may have a small grooved channel at its distal end in order to feed the strap over a rivet in the base of the buckle. 
         [0014]    Therefore, the prosthetic attachment system is easily accessible, effective, simple, and easy to use. The versatility and simplicity, and non-interfering design of the invented prosthetic attachment system helps provide reliable and comfortable suspension for an artificial limb on a great number of persons with limb deficiency. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a close-up, lateral view one embodiment of the prosthetic attachment system according to the invention, installed on a user&#39;s residual limb. 
           [0016]      FIG. 2  is a lateral view of the preferred prosthetic attachment system showing the strap as it enters the inside of the socket. 
           [0017]      FIG. 3  is a lateral view of the preferred prosthetic attachment system showing the strap after it has entered the socket and as it passes through an opening in the socket to the socket&#39;s outer surface. 
           [0018]      FIG. 4  is a lateral view of the preferred prosthetic attachment system showing the strap after it has entered the buckle. 
           [0019]      FIG. 5  is a lateral view of the preferred embodiment after the prosthetic is installed on the user&#39;s residual limb, showing the foot. 
           [0020]      FIG. 6  is a side view of one embodiment of the buckle-style latch mechanism of the present invention. 
           [0021]      FIG. 7  is a top view of the lever of the buckle of  FIG. 6 . 
           [0022]      FIG. 8  is a top view of the buckle of  FIG. 6 . 
           [0023]      FIG. 9  is a frontal view of the base frame of the buckle of  FIGS. 6 and 8 . 
           [0024]      FIG. 10  is a side view of one embodiment of the lever of the buckle of  FIGS. 6 and 8 . 
           [0025]      FIG. 11  is a frontal view of the pin of the buckle of  FIGS. 6-10 . 
           [0026]      FIG. 12A  is a plan view of one embodiment of an umbrella plate for attachment to an outside surface of a liner. 
           [0027]      FIG. 12B  is a side view of one embodiment of a strap according to the invention, for cooperating with, and connecting, the buckle-style lock and the umbrella plate. 
           [0028]      FIG. 13  is a ventral view of the especially preferred embodiment of the prosthetic attachment system showing two straps located laterally and medially. 
           [0029]      FIG. 14  is a close-up, lateral view of the especially preferred embodiment of the prosthetic attachment system of  FIG. 13 . 
           [0030]      FIGS. 15-17  are sequential, lateral views of the especially preferred embodiment of the prosthetic attachment system of  FIGS. 13 and 14  depicting the process of installing a prosthetic on a residual limb. 
           [0031]      FIG. 18  is a detail side view of the strap of  FIGS. 13-17  in relation to the buckle of  FIGS. 13-17 , before the strap is inserted in the buckle. 
           [0032]      FIG. 18A  is a detail side view of the strap of  FIGS. 13-18  in relation to the buckle of  FIGS. 13-18 , after the strap is inserted in the buckle. 
           [0033]      FIG. 19  is a top view of the especially preferred embodiment of the strap of  FIGS. 13-18 . 
           [0034]      FIG. 20  is a bottom view of the especially preferred embodiment of the strap  FIGS. 13-19 . 
           [0035]      FIG. 21A  is a front view of another embodiment of a prosthetic attachment system according to the invention, which features one embodiment of low profile buckles mounted internally and extending through the socket. 
           [0036]      FIG. 21B  is a close-up detail view of one of the buckles of  FIG. 21A . 
           [0037]      FIG. 22  is a front view of one embodiment of a prosthetic attachment system, wherein a residual limb with a liner is inserted into the socket of  FIGS. 21A  and B and one embodiment of a strap according to the invention extends from the liner, through the socket, and to the buckle to suspend the socket from the liner and limb. 
           [0038]      FIG. 23  is a perspective view the low-profile buckle of  FIGS. 21A ,  21 B, and  22 . 
           [0039]      FIG. 24  is a perspective, partial view of the buckle of  FIGS. 21A ,  21 B,  22 , and  23 , receiving the strap of  FIG. 22 . 
           [0040]      FIG. 25  is a front view of the buckle of  FIGS. 21-24 . 
           [0041]      FIG. 26  is a detailed side view of the buckle of  FIGS. 21-25 . 
           [0042]      FIG. 27  is a cross-sectional view of the buckle of  FIGS. 21-26 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0043]    Referring to the Figures, there are shown several, but not the only, embodiments of the invented prosthetic attachment system. In this Description and the Claims, the term “proximal” means toward the center/torso of the body, and so toward the top/upper end of the liner and prosthetic device. Thus, in the case of a prosthetic device for a person&#39;s leg, “proximal” would mean nearer or toward the upper thigh and trunk. “Distal” means away from the center/torso of the body, and so the regions of the liner or prosthetic device farther out from the trunk, and farther out on the leg. 
         [0044]    Referring to  FIGS. 1-12B , buckle  26  includes base  10 , which is mounted on the external surface of the hard socket  12  by means of a rivet  20 , glue or other fastener, or it may even be molded integrally with the socket  12 . The buckle  26  is positioned proximally higher up the socket than conventional “distal” locks that are mounted near the distal end of the socket, typically at the bottom of the inside “well” of the hard socket  12 . Connected to base  10  are a lever  11  and pin  11 ′ with e-clips  11 ″, which together create a biased system for receiving and capturing strap  22 , as seen in  FIGS. 8 and 12B . Strap  22 , as discussed below, is preferably secured to the liner  16 , by means of a umbrella  18  (see  FIG. 12A ), and is long enough to comfortably and conveniently extend from the middle to upper region of the side of the liner to reach the lower region of the liner (see  FIG. 2 ). 
         [0045]    Liner  16  may be a custom or a pre-manufactured liner as described in the Related Art section above. Examples of currently-available conventional liners are ICEROSS, ALPHA, LUXURY LINER, ALPS, SILIPOS (all trademarks). Modern urethane liners are especially preferred. As is well-known in this field, the currently-available liners listed above are examples of interface liners that are positioned between a residual limb and a prosthetic socket and are frequently called “suction liners,” “gel liners,” or “roll-on liners.” These liners typically are rolled-onto the residual limb for a suction, slight compression, and/or gripping connection of the inner gel layer of the liner to the skin of the residual limb. The liner-covered limb is then inserted into the prosthetic socket, and the outer surface/layer of the liner preferably forms a suction, grip, or other interference fit to the socket to interfere with the socket falling off the limb. The liners called by these names (“suction liners,” “gel liners,” or “roll-on liners”) include the modern “second generation” liners currently preferred by most wearers of prosthetics, which include a textile/fabric outer layer, as well as the older, “first generation” liners that typically did not have a textile/fabric outer layer. The term “suction liner” is still used by many manufacturers, prosthetic technicians, insurance and medicare/medicaid entities, and wearers of prosthetics, even though the modern liners, with their textile/fabric outer layers, do not form what would be called “true” or “pure” suction with the socket. See, for example, discussion of suction liners in Janusson, et al. (U.S. Pat. No. 6,706,364) and Janusson, et al. (U.S. Pat. No. 6,626,952). 
         [0046]    Strap  22  is connected at its proximal end to liner  16 , preferably by an umbrella  18  or other fixture or bracket. The umbrella  18  may be glued to the liner, as seen in  FIG. 2 . Umbrella  18 , as shown in  FIG. 12A , is preferably an aluminum plate structure of approximately ¾″ in diameter and ¼″ thick, with preferably a slightly-concave inner surface for contacting the glue, and with apertures at various locations on the umbrella to assist in receiving and better gripping of the glue that connects the umbrella  18  to the liner&#39;s  16  outside side surface. However, umbrella  18  may also be sewn onto or into liner  16 , or it may be formed integrally with liner  16 . Also, alternatively, other shapes of an attachment plates or other attachment means may be used instead of the umbrella, as long as preferably they are thin and easily slide/fit into the socket. 
         [0047]    The strap  22  is attached to the umbrella  18 , for example, with a 10/24-spanner bolt or screw. The screw is then tightened down to the umbrella  18 , rather than allowing the strap  22  to pivot around the screw. This results in the strap  22  being adjustable, allowing the user or prosthetist to move the strap  22  and then lock it into the optimum position, even if the strap  22  or lock mechanism have been attached to their respective structures in less-than-perfect position or location. 
         [0048]    When hard socket  12  is installed on the residual limb, it extends up over and around liner  16  and umbrella  18 , as shown in  FIG. 1 . Strap  22  extends from umbrella  18  on liner  16  a short distance on the inside of socket  12  through an aperture  15  in socket  12  to the external surface of socket  12  (see  FIGS. 2 and 3 ). There, the strap  22  continues to extend to and through the preferred buckle  26  attached on the outside surface of the socket  12 , as shown in  FIG. 4 . The buckle  26  adjustably receives the distal end of the strap  22 , by means of the strap  22  extending through the buckle  26  between the base  10  and the lever  11 . The strap  22  is pushed/pulled through the buckle  26  to the point where the hard socket  12  is securely, but comfortably secured around and connected to liner  16  via the strap  22  and umbrella  18  combination. This way, the advantages of the invention are realized. 
         [0049]    Strap  22  is preferably sufficiently rigid, sufficiently long, and is positioned so that, upon the limb/liner being inserted into the socket, the strap naturally tends to slide to and through the aperture  15 , to the buckle  26 , and through the buckle  26  with little or no need for the user to thread or pull the strap  22  through the aperture  15  or buckle  26 . A prosthetist will be able to adjust the strap and/or buckle locations and aperture size to enable this smooth movement and latching of the strap in the buckle. Optionally, the socket wall surface, on the interior or exterior, may be contoured to facilitate and direct the strap. 
         [0050]    The release button of the buckle  26  is buckle lever  11 , which features sharp edge  13 , as shown in  FIG. 7 . The top surface of base  10  ramps up in thickness in the distal direction. This provides for easier strap  22  entry into the buckle-style latch mechanism, and increasing pressure on the strap  22  when engaged by means of the buckle lever  11  pressing/ratcheting against the strap  22 . Edge  13  engages the sharp “ratchet teeth” of strap  22 , extending into the transverse detents  17  and abutting against the teeth walls upending from the strap top surface (see  FIG. 12B ). Any pull on the strap  22  in the proximal direction is resisted by the engagement of edge  13  in detents  17  and the pressure of lever  11  against e-clips  11 ″. The attachment system may be placed in a position on the liner and socket that the prosthetist deems most advantageous and convenient for the patient. The mechanism is attached to the exterior of the socket at a location determined by test socket fitting, but in any event, not at the distal end of the socket. Typically, when a single attachment system is employed, it will placed in a lateral position so that the user may reach it by reaching toward the outside of his limb. 
         [0051]    After mounting of the base  10  of the buckle  26  onto the socket  12 , the umbrella  18  onto the liner  16 , and strap onto the umbrella  18 , the roll-on prosthetic liner  16  of choice is applied to the patient. The patient can then step into the hard socket  12  and engage the attachment system, by inserting the strap  22  through the aperture  15  and into the buckle  26 . This procedure may be used in the retrofitting of the attachment system to an existing prosthetic. 
         [0052]    If a new prosthetic is being created, the liner  16  is applied to the patient, and the ideal location for the umbrella  18  is marked on liner  16 . A mold over the patient&#39;s limb and liner  16  is then taken. After the mold and liner  16  are removed, the umbrella  18  is then attached to the liner  16  in the location marked. From the mold the hard socket  12  is created, and the base  10  of the lock mechanism is attached in the proper location on the outside of hard socket  12 , and then the aperture  15  is created in hard socket  12  as above. 
         [0053]    The aperture  15  or any other opening through the socket preferably may be easily sealed by a gel suction wrap/cover, or other air-tight wrap or plug that preferably encases the lock mechanism and aperture. This allows and maintains a “suction” fit between the socket and the liner that improves the function of the prosthetic. 
         [0054]    As shown to best advantage in  FIGS. 2-5 , after donning of the prosthetic, the roll-on liner proximal wall extends generally parallel to the socket proximal wall, and the liner extends above the upper extremity edge of the socket while the strap at its attachment to the liner proximal wall is inside the socket. 
       Example 
       [0055]    The above attachment system was fit to three test patients. All three of these patients utilized ALPHA™ liners in a normal manner. The locking tab was attached to the ALPHA™ liners in a normal manner. Two of these patients were unilateral transtibial amputees, and one patient was a unilateral congenital above-knee amputee. The above-knee amputee was a congenital amputation resulting from PFFD, and his amputation level was consistent with a knee disarticulation level. All three of these patients either demonstrated problems with conventional distal pin-lock systems, or, in the case of the transfemoral amputee, did not have sufficient room to install any of the distal locking mechanisms currently on the market. These patients were using the prosthetic lock suspension according to the present invention on their prosthesis on a daily basis. These patients were all experimentally fit in June of 2000 and no problems were encountered with mechanical failures or with patient acceptance or satisfaction. We continue to monitor these patients at 2-3 week intervals. 
         [0056]    One may see, after reviewing the disclosure of this Description and the Drawings, that the invented attachment system tends to prevent rotation of the prosthesis on its longitudinal axis (axis extending between its proximal end and distal end) relative to the amputated limb. By providing one of the invented side-located, “proximally-located” attachment systems, such rotation is limited or prevented. This is because the strap extends from a fixed anchor location on the side of the liner/limb to a fixed anchor location on the side of the socket, thus connecting those two fixed locations together at substantially a fixed distance apart, thereby not allowing the anchor location on the socket to rotate any significant distance away from the anchor location on the liner. Although one of the invented attachment systems is preferred, more than one may possibly be used, for example, at two positions around the side of the limb/socket, as described below. 
         [0057]    Other benefits of the attachment system include comfort and ease of use. The preferred attachment system is simple to use, each to reach, and requires a minimum of dexterity. The externally-mounted lock mechanism eliminates the jamming of conventional distal locks often caused by a sock worn over the roll-on liner. 
         [0058]    While a ratchet-style buckle and strap combination is preferred, other releasable attachments and fasteners may be used. For example, extension members other than a flat strap with detents may be used, such as a cord(s), loop(s), tab(s), or other rigid or flexible extension members. Latch mechanisms other than a buckle may be used, such as a hook(s), clip(s), snap(s), or other devices that adjustably or non-adjustably grip the extension member. The connection between the extension member and the latch mechanism is preferably, but not necessarily, adjustable. This permits the user or the prosthetist to manipulate the connection for optimum use and comfort, either by lengthening or shortening the connection or by pivoting or otherwise moving the location of the extension member or latch mechanism. 
       An Especially Preferred Embodiment 
       [0059]    In the Description and Claims, the term “lateral” means on/toward the outer surface or region of the body, and therefore, on/toward the outer surface or region of the apparatus that is installed on the human body. Thus, a lateral surface of the liner or socket is an outer side surface, away from the inner or medial plane of the body. See lateral surfaces  101 ,  101 ′ of the liner and socket, respectively, in  FIGS. 13 and 14 , wherein the apparatus is on the left leg and  FIG. 13  is a ventral (front) view. The term “medial” means on/toward the inside or medial plane of the body. Thus, a medial surface of the liner or socket is an inner side surface, away from the outside of the body. See medial surfaces  102 ,  102 ′ of the liner and the socket, respectively, in  FIG. 13 , wherein the apparatus is on the left leg. 
         [0060]    Referring to  FIGS. 13-17 , attachment systems are shown with improved straps and latch mechanisms that make donning and doffing the prosthesis more convenient and comfortable. The embodiment of  FIGS. 13-17  comprises two straps  122 , one attached to the lateral surface  101  of the liner  16  and one attached to the medial surface  102  of the liner  16 , as shown in  FIG. 13 . These two straps are secured to the liner by means of an umbrella  18  described above and shown in  FIGS. 1-12B . 
         [0061]    The especially preferred strap  122  has a “nipple” shaped tab extension  114 , or other tapered, narrow tip, at its distal end. The extension  114  preferably has a width less than half of the width of the strap  122 . The extension facilitates the strap  122  from the inside of the socket  12  to the socket&#39;s external surface and through the buckle  126  (see  FIG. 19 ). The bottom surface  123  of the especially preferred strap  122  may have a longitudinal channel  124 , or other grove or ramp-like shape at the distal end, to prevent the strap  122  from “catching” on the rivet  20  in the base  110  of the buckle  126 . The thinness (from top surface to bottom surface) of the central region of the distal end, caused by the channel  124 , aids in smooth insertion of the strap  122  into the buckle  126 , and allows the distal end to slide over the rivet  20 . This way, the rivet  20  need not be lowered or countersunk into the base  110 . Alternatively, the entire bottom surface of the distal end of the strap may be slanted/thinned, but this would result in a weaker distal end. 
         [0062]    In order to install the socket  12  on the residual limb, the user places the two straps  122  inside the socket  12  and then feeds them through two apertures  115  located medially and laterally in the socket&#39;s  12  side wall, as seen in  FIGS. 15 and 16 . Once the tabs  114  of the straps  122  exit the apertures  115  to the external surface of the socket  12 , they feed into two buckles  126 , distal from the apertures  115 , on the medial and lateral surface of the socket  12  (see  FIGS. 16 and 17 ). Preferred buckle  126  may include a spring-biased member with one or more sharp edges  113 , that frictionally engage transverse detents  17  located between transverse raised ridges on the strap&#39;s surface. Connected to each base  110  of the buckles  126 , are a lever  111 , pivot axle pin  111 ′, and e-clips  111 ″ or other biasing spring or member, which together create a biased system for receiving and capturing the straps  122 . The top surface of each base  110  ramps up towards the distal end of the buckle  126 , allowing easy insertion of the straps  122 , as shown in  FIG. 18 . As the distal end of each strap  122  moves into the proximal end of each buckle  126 , the sharp edge or edges  113  of the buckles  126  engage the transverse detents  17  of the straps  122  (see  FIG. 19 ). The channel  124 , on each strap  122 , bypasses the rivet  20  in base  110  of its respective buckle  126 , allowing the distal end strap  122  to exit the distal end of the buckle  126 , in turn securing the socket  12  to the residual limb (see  FIG. 19 ). 
         [0063]    The preferred method for releasing the straps  122  from the buckles  126 , is for the user to pull up on the distal end of each lever  111  to pivot the lever  111  into a raised position as shown in  FIG. 18A , which corresponds to pivoting the distal end of the lever  111  away from the socket. This, in turn, disengages the sharp edge or edges  113  of each buckle  126  from the transverse detents  17  of each strap  122  (see  FIGS. 18 and 19 ). The user is then able to remove the socket  12  from the residual limb by holding on to each lever  111  and pulling the socket  12  off the liner and also by maneuvering his/her residual limb out of the socket. Having a plurality of attachment systems for a single prosthetic device may improve stability and comfort for the user. By utilizing lateral and medial strap and buckle combinations, rotation of the prosthetic device relative to the user&#39;s residual limb is minimized, if not prevented. Further, the levers of the lateral and medial buckles provide a hand-hold for the user, especially during removal of the socket from the liner-covered residual limb. The lift-to-release buckle levers may be easier to operate and may provide a better hand-grip for the user, compared to the embodiment of  FIGS. 1-12B  which requires that the user push and hold down the levers of the buckles during removal of the prosthesis. 
         [0064]    The buckles illustrated in  FIG. 13  are depicted to be quite large and to protrude significantly from the socket, but the buckles may be made to small and low-profile, so that the strap and buckle combination is discreet when covered by clothing and comfortable for walking without the buckle catching on the other leg or clothing. 
       A Low Profile Buckle Embodiment 
       [0065]    Alternative buckles may be made to be small and/or low-profile, so that the strap and buckle combination is discreet when covered by clothing and comfortable for walking without the buckle catching on the other leg or clothing. 
         [0066]    One way of establishing a low-profile system is to locate at least a part of a buckle/latch mechanism(s) inside the socket wall, rather than on the socket wall. For example, a portion of the buckle may be recessed into the socket wall from the outer surface, but, more preferably, at least a portion of the buckle extends through the socket wall from at or near an internal surface of the socket. Either way, the buckle is, in effect, “sunk” into the socket rather than resting on the outer surface of the socket, so that the strap enters the buckle closer to the outer surface of the socket and the buckle protrudes from the socket to a lesser amount. The preferred buckle has only about 25-50%, and more preferably about 25%, of its thickness above the plane of the outer surface. 
         [0067]    Referring to the embodiment shown in  FIGS. 21-27 , one or buckles  226  are mounted in the socket by inserting the buckle  226  through an opening in the socket wall. The buckle extends through the wall to protrude slightly beyond the external surface of the socket. Strap  222  may enter the buckle at or near the plane of the external surface of the socket; and the buckle may protrude minimally from the socket, so that it tends not to catch on the user&#39;s clothing or other leg, and tends to be less noticeable. 
         [0068]    Preferably, two straps  222  and two buckles  226  are used. The straps  222  are attached to the lateral surface  101  and medial surface  102  of the liner  16 , respectively, as shown in  FIGS. 21A and 22 , by an “umbrella” or other attachment. The buckles  226  extend through the wall of the socket, with the bottom surface  250  of the buckle preferably being coplanar with the inside surface  103 . Top surface  260  of the buckle, which is configured for receiving the strap, is preferably approximately coplanar with the lateral or medial outside surfaces  101 ′,  102 ′ of the socket near the buckle. One may understand that, due to the typically generally-cylindrical shape of the inner and outer surfaces of the sides of the socket, neither the inner or outer surfaces are expected to be exactly planar in the region of the buckle. However, given the relatively small size of the preferred buckles (less than about 1.5 inches in width transverse to the length of the socket), one may still say that the bottom surface  250  of the buckle is generally parallel to the plane of the inner surface  103  of the socket, and one may still say that the top surface  260  (which is typically planar but slanted/ramped) is generally parallel to the plane of the outer surface  101 ′,  102 ′. 
         [0069]    In this discussion, “top” is used to refer to the surface  260  across which the strap slides or otherwise moves, and “bottom” is used to refer to the opposing surface, as this is convenient in view of the orientation of the buckle  226  when it is set, for example, on a table prior to installation. This terminology is not intended to limit the orientation of the buckle when installed in the prosthetic system, however. 
         [0070]    Buckle  226  preferably comprises base  210  having a flange  230  around at least part of the base. The flange  230  is thinner than the main body of the base  210  and thinner than the thickness of the socket wall. This way, the flange lies within the wall of the socket but does not extend all the way through the wall, so that a portion of the socket wall (such as lip  270 ) extends over the flange to help prevent the buckle from being pulled out of the socket wall from the outside of the socket. 
         [0071]    Connected to the base  210  are a lever  211  and pin  211 ′ with resilient e-clips  211 ″, which together create a bias system generally located over, and cooperating with, top surface  260  to retain strap  222  in the buckle. As shown to best advantage in  FIGS. 22 and 24 , the top surface  260  of the base  210  ramps up slightly in thickness in the distal direction. Proximal end  260 ′ of the top surface is at or slightly below the plane of the outer surface of the socket wall, to assist in easy sliding of the strap into the buckle from the distal region of the socket. Distal end  260 ″ of the top surface is farther out from said plane for better clamping of the strap between the top surface  260  and the bias system and for placing the end of the strap slightly distanced from the outside of the socket in a position that is easily reachable by the user ( FIG. 22 ). 
         [0072]    The lever  211  acts as both the securement device for fastening the strap  222  in the buckle  226 , as well as the release button to allow release the strap  222  from the buckle  226 . The lever  211  preferably comprises a generally sharp edge  213  at its distal end. The edge  213  engages the “ratchet teeth” of strap  222  by extending into the transverse detents  17  and abutting against the teeth walls upending from the strap top surface. A pull on the strap  222  in the proximal direction is resisted by the engagement of edge  213  in detents  17  and the pressure and bias of lever  211  against e-clips  211 ″. 
         [0073]    The preferred, but not the only, method of installing buckles  226  through the wall of the socket  12  is as follows. The socket  12  is molded with a dummy piece in the place where the buckle  226  will be inserted, wherein the dummy piece will typically be about the width and length of the base without its flange. This typically results in the space for the buckle substantially being “reserved” so that the laminate materials used to make the socket do not fill said space. A thin layer or layers of laminate over the outer surface of the dummy piece may form and remain after the molding, which layer/layers may be drilled or cut away so that the dummy piece may be “popped out” the exterior of the socket. After the dummy piece is removed, the wall around the dummy-created hole is modified to receive the flange, that is, so that the wall has step or lip  270  extending over the hole at the outer perimeter of at least some areas of the hole. This way, the buckle base may be inserted into the stepped hole, with the flange retained by the lip  270  and with the ramped top surface being exposed on/near the outside of the socket and the bias system protruding from the socket. 
         [0074]    At least a portion of the base is adhered to the interior surface  103  of the socket, for example, the flange  230  is preferably adhered to the lip  270  by glue, other adhesive, or other securement means. A rivet, screw, or other fastener may be used to secure various embodiments of the buckle in the wall of the socket, for example, a rivet through the flange  230  and through the lip  270 . Instead of such hardware, however, it is preferred that the dimensions of the buckle be formed to make it unlikely that it will be pulled out of the socket by the strap and that adhesive further ensures this and also keeps the buckle in place in the wall when there is no force being applied to the buckle by the strap. 
         [0075]    Strap  222  is preferably sufficiently rigid, sufficiently long, and is positioned so that, upon the limb/liner being inserted into the socket, the strap naturally tends to slide to and through the aperture  215  in the socket, to the buckle  226 , and through the buckle  226  with little or no need for the user to thread or pull the strap  222  through the aperture  215  or buckle  226 . 
         [0076]    Strap  222  optionally may have a tapered, narrow, or otherwise specially-shaped tip or extension at its distal end, to assist in the strap  222  easily moving through the aperture  215 , and along the buckle; this is not know in  FIGS. 21-27 , but one embodiment is shown in  FIGS. 13-20 . Such a tip or extension facilitates the strap from the inside of the socket  12  to the outside of the socket and through the buckle because the tip/extension tends to center the strap as the tip/extension enters the aperture or buckle. 
         [0077]    Also in a similar manner as described for the strap shown in  FIGS. 13-20 , the bottom surface of strap  222  may have a longitudinal channel, or other grove or ramp-like shape especially at the distal end, to prevent the strap  222  from “catching” in the base  210  of the buckle  126 . This may be helpful, especially in the case of the buckle comprising a rivet or other fastener that might get in the way of the strap  222 , but, for the preferred low-profile buckle with proximal surface  260 ′ being recessed relative to the surrounding outer surface of the socket, the channel or grove in the bottom surface of the strap is typically not as necessary. 
         [0078]    In order to install the socket  12  on the residual limb, the user places the two straps  222  inside the socket  12  and then feeds them through two apertures  215  located medially and laterally in the socket&#39;s  12  side wall, as illustrated by  FIGS. 21 and 22 . Once the ends of the straps  222  exit the apertures  215  to the external surface of the socket  12 , they tend to automatically feed into two buckles  226 , distal from the apertures  215 , on the medial and lateral surfaces of the socket  12  (see  FIGS. 21 and 22 ). 
         [0079]    The preferred method for releasing straps  222  from the buckles  226 , is for the user to push down on the proximal end of each lever  211  to pivot the lever  211  from the “lowered position” of  FIG. 26  into the “raised position” as shown in  FIG. 27 , which corresponds to pivoting the distal end of the lever  211  away from the socket  12 . This, in turn, disengages the sharp edge or edges  213  of each buckle lever  211  from the transverse detents  17 . The user is then able to remove the socket  12  from the residual limb, preferably by continuing to keep the buckles unlatched by pushing on the proximal end of the lever  211 , by pushing the socket  12  off the liner  16 , and also by maneuvering his/her residual limb out of the socket  12 . 
         [0080]    Alternatively, lift-to-release buckle levers, for example, as illustrated in  FIGS. 13-18 , may be easier to operate than push-to-release levers for some users and may provide a better hand-grip for some users. The inventors envision that both styles may be used in embodiments of low profile buckles. 
         [0081]    While lateral and medial positions for two strap and buckle combinations are preferred, a single strap and buckle combination may add prosthetic stability and operability for many users. Alternatively, other numbers and arrangements of straps and buckles/latch mechanisms may be effective. 
         [0082]    Preferred levers  11 ,  111 , and  211  are deemed to be convenient and reliable for latching and unlatching their respective buckles, and preferably, each lever is biased into the latched position and requires positive action by the user or prosthetist to unlatch it. However, other styles of latch mechanisms may be used, such as other pivotal arms or hooks, snaps, clips, loops, ties, or other releasable locks and latches. 
         [0083]    Preferably, the prosthesis attachment system comprises the invented extension member and latch system, with or without the aid of suction between the liner and the socket, but no other straps or attachments. Preferably, there is no belt or strap extending to encircle part of the user&#39;s body, and preferably no attachment between the distal end of the limb/liner and the bottom of the well of the socket. 
         [0084]    Although this invention has been described above with reference to particular means, materials and embodiments, it is to be understood that the invention is not limited to these disclosed particulars, but extends instead to all equivalents within the broad scope of this disclosure and the following claims.