WO2018224833A1

WO2018224833A1 - Prosthesis for a through-knee amputee

Info

Publication number: WO2018224833A1
Application number: PCT/GB2018/051551
Authority: WO
Inventors: Grigorios GRIGORIADIS; Christopher NATT
Original assignee: Imperial Innovations Limited
Priority date: 2017-06-08
Filing date: 2018-06-07
Publication date: 2018-12-13
Also published as: GB201709116D0; GB2563257A

Abstract

The present disclosure provides a prosthesis for a through-knee amputee.The prosthesis comprises a proximal limb portion and a distal limb portion. The proximal limb portion comprise a socket which is configured to receive the upper leg of a through-knee amputee.The prosthesis also comprises at least two hinges to connect the proximal limb portion to the distal limb portion so that they can rotate about a single axis of rotation. The prosthesis also comprises a contact member and an engagement element. One of the contact member and engagement element is attached the proximal limb portion and the other of the contact member and engagement element is attached to the distal limb portion. One of both of the contact member and engagement element are biased towards the other. The contact member is adapted so that when the proximal limb portion and the distal limb portion undergo extension from a position of flexion, the contact member contacts the engagement element to displace the engagement element and/or contact member against the bias.

Description

PROSTHESIS FOR A THROUGH-KNEE AMPUTEE

TECHNICAL FIELD

The present disclosure relates generally to a prosthesis for a through-knee amputee. In particular, the present disclosure may relate to a low-cost lower leg prosthesis for a through-knee amputee.

BACKGROUND

There is an increasing need for an affordable and functional prosthetic device. In particular in developing nations, such as Cambodia. Cambodia in particular has a legacy of land mines which have resulted in a large number of amputee's requiring prosthetic devices.

Lower limb prosthesis made for developing markets are often too costly and too impractical for widespread use in developing nations. Affordable prostheses have previously been developed for such markets. One example is the lower limb prosthesis which was developed in the 1970's by the International Committee of the Red Cross (ICRC). This prosthesis was designed as a cost effective prosthesis for trans-femoral amputees. The ICRC prosthesis remains unchanged and has a number of problems associated with it. For example, it has a number of wear points that are prone to failure, users also report it lacks stability. It also has limited functionality and its bulky centrally located hinge means it cannot be modified to accommodate through-knee amputees.

Transfemoral amputation for which the ICRC prosthesis was designed remains the most common form of lower limb amputation. In transfemoral amputation the femur is cut along its length and the portion of leg below the cut is removed. Clinical studies have demonstrated that significantly higher quality of life can be obtained from through-knee amputation compared to transfemoral amputation.

In through-knee amputation the tibia is disarticulated from the femur with the femur remaining intact.

The number of amputees receiving through-knee amputation is increasing because of the improved clinical outcome. Through-knee amputation provides different prosthesis design constraints compared to transfemoral amputation, for example there is less space to accommodate the mechanism of prosthesis due to increased femur length.

Therefore, there is a need for a low-cost through-knee prosthesis. A low-cost prosthesis is a prosthesis suitable for use in developing nations, rather than a prosthesis designed for use in developed markets. For example a low-cost prosthesis should be formed from low cost components, it should also be durable and comprise only readily repairable or replaceable components. It should also be capable of being manufactured and repaired in basic workshops. In spite of the effort already invested in the development of through-knee prosthesis further improvements are desirable.

SUMMARY The present disclosure provides a prosthesis for a through-knee amputee. The prosthesis comprises a proximal limb portion and a distal limb portion. The proximal limb portion comprise a socket which is configured to receive the upper leg of a through-knee amputee. The prosthesis also comprises at least two hinges to connect the proximal limb portion to the distal limb portion so that the limb portions can rotate about a single axis of rotation. The prosthesis also comprises a contact member and an engagement element. One of the contact member and engagement element is attached the proximal limb portion and the other of the contact member and engagement element is attached to the distal limb portion. One or both of the contact member and engagement element are biased towards the other. The contact member is adapted so that when the proximal limb portion and the distal limb portion undergo extension from a position of flexion, the contact member contacts the engagement element to displace the engagement element and/or contact member against the bias.

Displacing the engagement element and/or contact member against the bias may slow the swing of the proximal limb portion during swing phase of the gait. This may provide a prosthesis that is easier for the amputee to walk with. It may also prevent uncontrolled swing of the limb which may otherwise increase the wear on hinges. Because the prosthesis comprises two laterally spaced hinges, load from the amputee's weight is spread between each hinge, reducing wear compared to a single hinge. This also means that because the load is spread, the load bearing requirements of the hinges are reduced. This means lower specification hinges can be used, and the prosthesis can comprise bearings from commonly available machinery e.g. bicycle hubs. This also means the hinges can comprise components that can be readily obtained and easily maintained.

Furthermore, because load is distributed between two hinges, thinner hinges can be used. This may further maintain good visual appearance of the prosthesis, especially when an amputee is seated with the prosthesis.

The use of two hinges rotating about a single axis may also provide space for the socket to accommodate the leg of a through-knee amputee. in embodiments, the contact member may comprise an elongate portion with a region of increasing thickness along the length of the elongate portion. in embodiments, the engagement element may comprise a roller. In embodiments, the engagement element may be biased against the contact member by a biasing means. In embodiments, the contact member may be biased against the engagement element by a biasing means. in embodiments, the contact member may be attached to or integrated into a distal portion of the socket. in embodiments, the engagement element may be connected to the distal limb portion and may be designed to move in a direction parallel to a longitudinal axis of the distal limb portion, and relative to the distal limb portion. in embodiments, the contact member may comprise one or more movement stops to limit the range of rotation of the distal limb portion relative to the proximal limb portion. in embodiments, the socket may comprise a condyle portion to locate the femoral condyles of a through-knee amputee. In embodiments, the at least two hinges may be positioned laterally and medially of the socket, in embodiments, two hinges may be positioned laterally and medially of the condyle portion. in embodiments, the prosthesis may comprise a locking mechanism to lock the proximal limb portion and the distal limb portion in a fixed position.

In embodiments, the locking mechanism may comprise a recess fixedly connected to one of the proximal limb portion or the distal limb portion. The locking mechanism may comprise a locking element movabiy attached to the other of the proximal limb portion. The locking element may engage with the recess to lock the proximal limb portion and the distal limb portion in a fixed position. in embodiments, the locking element may engage with the recess to lock the proximal limb portion and the distal limb portion in a fixed position when a weight-bearing load is transferred through the prosthesis. In embodiments, the locking element may disengage from the recess to unlock the proximal limb portion and the distal limb portion when a weight-bearing load is unloaded from the prosthesis. in embodiments, the recess may be comprised as part of the contact member. in embodiments, the engagement element may also function as the locking element. in embodiments, the locking element may be biased away from the recess by a locking biasing means. in embodiments, the distal limb portion may comprise a movable member configured to move relative to the distal limb portion when a weight-bearing load on the prosthesis is applied or removed. In embodiments, the distal limb portion may comprise a ground contacting portion, and the ground contacting portion may be connected to the movable member. In embodiments, the proximal limb portion may comprise a movable member configured to move relative to the proximal limb portion when a weight-bearing load on the prosthesis is applied or removed. In embodiments, the engagement element may be connected to the movable member and the engagement element may engage with the recess to lock the prosthesis in a fixed position when a weight-bearing load is applied to the prosthesis. In embodiments, the movable member may be biased by the locking biasing means. in embodiments, the distal limb portion may comprise a Y- or U- shaped member connected to the two hinges, in embodiments, the engagement element and/or locking element may be connected to the Y- or U- shaped member, alternatively, the contact member and/or recess may be connected to the Y- or U- shaped member. In embodiments, the movable member may be movable through the Y- or U- shaped member, in embodiments, the arms of the Y- or U- shaped member may be adjustable in length.

The present disclosure provides a prosthesis for a through-knee amputee. The prosthesis comprises a proximal limb portion and a distal limb portion. The proximal limb portion comprises a socket which is adapted to receive the upper leg of a through-knee amputee. The prosthesis also comprises at least two hinges to connect the proximal limb portion to the distal limb portion so that the limb portions can rotate about a single axis of rotation. The prosthesis also comprises a locking mechanism. The locking mechanism comprises a recess fixedly connected to one of the proximal limb portion or the distal limb portion; and a locking element movably attached to the other of the proximal limb portion or the distal limb portion. The locking element is adapted to engage with the recess to lock the proximal limb portion and the distal limb portion in a fixed position. In embodiments, the locking mechanism may comprise any aspect of a locking mechanism described herein. In embodiments, the prosthesis may also comprise a contact member and an engagement element, in any configuration described herein. The preceding summary is provided for purposes of summarizing some embodiments to provide a basic understanding of aspects of the subject matter described herein. Accordingly, the above- described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter described herein in any way. Moreover, the above and/or proceeding embodiments may be combined in any suitable combination to provide further embodiments. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE FIGURES Aspects, features and advantages of embodiments of the present disclosure will become apparent from the following description of embodiments in reference to the appended drawings in which like numerals denote like elements.

Figure 1 A shows a lateral view of an embodiment prosthesis, including an exploded view of a portion of the prosthesis.

Figure 1 B shows a frontal view of the embodiment prosthesis of figure 1A.

Figure 2 shows a lateral view of a portion of an alternative embodiment prosthesis.

Figures 3A and 3B show a schematic in a lateral view of a prosthesis in a position of flexion and a position of extension. Figures 4A and 4B show a lateral view of a portion of an embodiment prosthesis in flexion and extension respectively.

Figure 5 shows a frontal view of a portion of an embodiment prosthesis showing the condyle portion of a socket.

Figure 6 shows a frontal view of an embodiment prosthesis comprising a locking mechanism. Figure 7 shows a lateral view of an alternative embodiment prosthesis comprising a locking mechanism.

Figure 8 shows a lateral view of an embodiment prosthesis comprising a locking mechanism and an energy attenuating mechanism.

Figure 9 shows a frontal view of an alternative embodiment prosthesis comprising a locking mechanism and an energy attenuating mechanism.

Figures 10A-C show components suitable for embodiments of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Before describing several embodiments of prosthesis, it is to be understood that the prosthesis is not limited to the details of construction or functional definitions set forth in the following description. It will be apparent to those skilled in the art having the benefit of the present disclosure that the prosthesis is capable of other embodiments and of being practiced or being carried out in various ways.

As used herein, the term "through-knee amputee" may refer to an amputee with the lower leg removed (i.e. removing the tibia, fibula, scapula and foot), retaining the femur in its entirety including the femoral condyles. As used herein, the terms "proximal" and "distal" may respectively refer to positions close to and distant from the main centre of mass of the body. Proximal and distal are used herein in relation to a through-knee prosthesis, thus proximal may refer to parts of the prosthesis that are close to the main centre of mass of the amputee when the prosthesis is in use. Similarly, distal may refer to positions of the prosthesis that are distant to the main centre of mass amputee when the prosthesis is in use, i.e. close to the ground.

As used herein, the term "flexion" and "extension" refer to directions of rotation of the prosthesis and positions of the prosthesis. Extension may refer to a position of the prosthesis where the proximal and distal limb portions are aligned approximately straight i.e. when the prosthesis is used in a standing position. Flexion may refer to a position of the prosthesis where the proximal and distal limb portions are not aligned approximately straight i.e. the prosthesis is in a bent position. Similarly, the proximal and distal limb portions may be relatively rotated in extension, from a position of flexion towards a position of extension, i.e. straightening the prostheses. The proximal and distal limb portions may also be relatively rotated in flexion i.e. flexing/bending the prosthesis. As used herein, the term "proximal limb portion" may refer to a portion or segment of the prosthesis substantially proximal of the axis of rotation. , the term "proximal limb portion" may performs a function similar to the upper leg when in use. The proximal limb portion may connect to the upper leg of the amputee when in use.

As used herein, the term "distal limb portion" may refer to a portion or segment of the prosthesis substantially distal of the axis of rotation. The distal limb portion may replicate the functioning of the lower leg of the amputee when in use.

As used herein, the term "axis of rotation" may refer to a single axis about which the proximal and distal limb portions rotate relative to each other.

As used herein, the term "contact member" may refer to a surface arranged to be contacted by the engagement element.

As used herein, the term "engagement element" may refer to an element configured to contact the contact member. Non-limiting examples include a roller and a surface adapted to slide over the contact member.

As used herein, the term "locking mechanism" may refer to a mechanism for a prosthesis useable to lock the prosthesis in a fixed position. For example, the locking mechanism may lock the prosthesis in a position of extension to allow the amputee to stand.

As used herein, the term "socket" may refer to a part of the prosthesis that engages with the upper leg of the amputee when the prosthesis is in use. In embodiments, the socket may comprise a "condyle portion of the socket" which may refer to a portion of the socket that surrounds the condyles of the femur when the upper leg of a through-knee amputee is inserted into the socket.

As used herein, the term "recess" may comprise a groove, trench, void, hollow or spacing, or any concave structure capable of receiving a locking element. As used herein, the term "locking element" may comprise any element, member or body configured to engage with the recess.

As used herein, the term "locked in a fixed position", may refer to securing the prostheses in a position to prevent rotation between the proximal and distal limb portions.

As used herein, the term "biasing means" or "locking biasing means" may refer to any biasing element such as a spring, elastomer, resilient member or similar unit that is capable of applying a biasing force. The locking biasing means is a biasing means comprised as part of the locking mechanism, it may comprise any biasing element capable of applying a biasing force

As used herein, the term "weight-bearing load" may refer to load from the weight of the amputee on the prosthesis when it is in use. The load may be equivalent to a portion of the body weight of the amputee. In particular, "weight bearing load" may refer to a load resulting from a portion of body- weight of the amputee that is transferred to the prosthesis when the prosthesis is in use in a standing position.

As used herein, the term "longitudinal axis of limb portion" may refer to an axis approximately aligned with the length of a limb portion. In embodiments, the longitudinal axis of limb portions of the prosthesis may be approximately symmetrical about the sagittal plane with the longitudinal axis of the femur and tibia of the amputees opposing leg. In embodiments, the longitudinal axis of the distal limb portion may extend from a foot portion to the centre of rotation of the prostheses. In embodiments, the longitudinal axis of the proximal limb portion may extend from the centre of rotation to the acetabulum of the amputee, when the prosthesis is in use. Referring to figure 1 A and figure 1 B, an embodiment prosthesis 100 for a through-knee amputee is shown. The prosthesis 100 comprises a proximal limb portion and a distal limb portion, shown generally by the numerals 102 and 106. The proximal limb portion 102 comprises a socket 104. The socket 104 is shaped to receive the upper leg of a through-knee amputee. The proximal limb portion 102 and a distal limb portion 106 are arranged to rotate around a single axis of rotation 110. The proximal limb portion 102 and a distal limb portion 106 are joined by at least two hinges 108 to provide the rotation around the single axis of rotation 110. In embodiments, the hinges may be positioned laterally and medially of the socket 104, as shown in figure 1 B. The prosthesis 100 also comprises a contact member 112 connected to the proximal limb portion 102 or the distal limb portion 106. In figure 1A and figure 1 B the contact member 112 is shown connected to the proximal limb portion 102, and is mounted on a distal surface of the socket. However, it is also envisioned that the contact member may be connected the distal limb portion 106 as illustrated in the prosthesis 200 of figure 2. In embodiments where the contact member 112 is connected to the proximal limb portion 102, it need not be mounted to the socket as shown in figure 1 , but may be connected to any structure that rotates with the proximal limb portion 102.

The prosthesis 100 also comprises an engagement element 114 connected to the other of the proximal limb portion 102 or the distal limb portion 106. In figure 1A and figure 1 B the engagement element 114 is shown mounted to the distal limb portion 106. However, it is also envisioned that the engagement element 114 may be mounted on the proximal limb portion 102 as illustrated in the prosthesis 200 of figure 2. In embodiments where the engagement element 114 is connected to the proximal limb portion 102, the contact member 112 is connected to the distal limb portion 106, and vice versa. The engagement element 114 and contact member 112 are biased towards each other. The biasing may involve one or both of the engagement element 114 and contact member 112 being movably or deformably biased towards each other. An embodiment of this arrangement is shown in the exploded portion of figure 1A with the connection of the distal limb portion to the hinge omitted for clarity. In figure 1A and 1 B the engagement element 114 is shown biased towards the contact member 112. Equally, the contact member 112 may be biased towards the engagement element 114, or both. In figure 1A and 1 B the engagement element 114 is shown movably biased towards the contact member 112 with a biasing means 116, which in embodiments, may comprise a spring or other known resilient member. However, the invention need not be limited to such. In a non-limiting example embodiment, one or more of the engagement element 114 and the contact member 112 may comprise a deformable material, and so the biasing may comprise deformation of one element against the other element. In a similar non-limiting example, one of the engagement element 114 or the contact member 112 may be mounted to the socket 104 or other structural element of the prosthesis, and the socket or other structural element may be deformable so as to bias the element mounted to it against the other element.

Figure 3A and 3B shows the proximal limb portion 102 and a distal limb portion 106 in a position of flexion in 3A and extension in 3B respectively. Figure 3A also illustrates the approximate longitudinal axes 301 , 302 of the proximal and distal limb portions respectively. The hinges 108 of the prosthesis permit the proximal limb portion 102 and a distal limb portion 106 to rotate in flexion and extension. The contact member 112 is shaped and positioned so that the when the prosthesis 100 moves from a position of flexion (e.g. in 3A) towards a position of extension (e.g. in 3B), i.e. the prosthesis 100 straightens out from a bent position towards a standing position, the contact member 112 contacts the engagement element 114 to increase its displacement against the bias. Figure 4 provides an example of this for an embodiment comprising a contact member 112 mounted to socket 104 and an engagement member 114 biased towards the contact member 112 by biasing means 116. In this non-limiting exemplary embodiment, the engagement element 114 is arranged to move approximately parallel to the longitudinal axis of the distal limb portion.

As the prosthesis 100 moves from a position of flexion towards extension, the displacement of an element against the bias transfers energy from the movement of the distal limb portion in relation to the proximal limb portion, into the biasing means 116. In the embodiment shown in figure 4, energy is transferred into the biasing means 116 as the limb is moved from a position of flexion (figure 4A) towards a more extended position (figure 4B). As the limb is moved towards extension, the engagement element 114 is displaced distally against the biasing means 116, causing work to be stored by the biasing means 116. Similarly, in embodiments where the contact member 112 or engagement element 114 are deformable or mounted to a deformable surface, biasing is provided by the material deformation. This may include deformation of the element or member or a structure to which an element or member is mounted to.

The transfer of energy from rotation of the limb portions to displacing the contact member/engagement element against the bias may cause deceleration of the proximal limb portion during the swing phase of the gait cycle. This may give the user of the prosthesis greater control during walking because the distal limb portion of the prosthesis is prevented from moving forward with excessive momentum. By attenuating the momentum of the distal limb portion during the swing phase, the forces experienced by the prosthesis during swing phase may also be reduced, further reducing wear on the hinges. Furthermore, when the prosthesis is in or close to full extension, for example during standing, the biasing means will be at or close to a maximally displaced position. Therefore the biasing force from the biasing means will be at or close to maximum. In this position, some of the load of the amputee's weight in the standing position may be transferred from the proximal limb potion to the distal limb portion via the contact member and biasing means, reducing the load on the hinges. This may further reduce the wear on the hinges further increasing the longevity of the prosthesis. Therefore, the hinges of the prosthesis may comprise lower specification components.

In embodiments, the contact member may be mounted to socket. The contact member may be curved to conform to the curvature the distal surface of the socket. The contact member may comprise a flexible material to allow it to conform to the curvature of a distal surface of the socket. In embodiments, the contact member may be integral with or comprised as part of the distal surface of the socket.

In embodiments, the contact member may comprise an elongate shape with a region of increasing thickness along the length of the elongate portion. In embodiments the thicker region is positioned to contact the engagement element when the knee is in or close to a position of extension. Thus, the more the knee is extended, the more the contact member or engagement element are displaced. In embodiments, the engagement element contacts the contact member at increasingly thinner regions of the contact member as the prosthesis is in increasingly deeper positions of flexion.

The contact member may be elongate in shape and increase in thickness along its length, such that one end is thicker than the other. In embodiments, the thick end may be positioned so that it is in contact with the engagement element when the prosthesis is at or close to full extension (i.e. in a standing position). Thus, the thick end may cause a greater displacement of the engagement element.

In embodiments, the engagement element 114 may comprise a friction reducing element to reduce friction between the engagement element and the contact member. For example, the friction reducing element of the engagement element 114 may comprise one or more rollers (as shown in figures 1 to 4) or a low friction material. Similarly, the contact member may comprise a friction reducing surface to lower friction between the engagement element and the contact member.

In embodiments, the engagement element 114 is biased against the contact member by a biasing means 116. The biasing means may comprise a spring or other biasing member. Non-limiting examples of springs include elastomers, leaf springs, air spring and coil springs.

In embodiments, the engagement element or contact member may be arranged to move parallel to the longitudinal axis of the proximal limb portion or the longitudinal axis of the distal limb portion. In embodiments, the engagement element may be connected to the distal limb portion 106 and designed to move in a direction parallel to a longitudinal axis of the distal limb portion.

In embodiments, the engagement element may be mounted to moveable support member, the support member may be arranged to move parallel to the longitudinal axis of the proximal limb portion or the longitudinal axis of the distal limb portion. The support member may be positioned internally of a hollow member of the distal limb portion. For example, the support member may be arranged to slide within a member of the distal limb portion. For example, the support member may slide within or move telescopically within a member of the distal limb portion. Similarly in other embodiments, the support member may slide externally to, flex or rotate in relation to the distal limb portion.

In embodiments, the contact member may comprise a recess. In embodiments, the contact member may comprise one or more movement stops to limit the range of rotation of the distal limb portion relative to the proximal limb portion. The movement stops may be positioned and shaped to prevent the engagement element from moving past them when the proximal and distal limb portions are rotated relative to each other. Figure 4 shows two movement stops 118, 119 positioned to prevent over flexion and extension of the prosthesis. However, in embodiments, a prosthesis may comprise only one movement stop. A movement stop may comprise a raised projection extending from the contact member, or may be positioned adjacent to the contact member. In embodiments where the contact member comprises a recess, a lip of the recess or the recess itself may function as a movement stop. Referring to figure 5, the socket 104, hinges 108 and part of a distal limb portion of a prosthesis is shown in an anterior view. The socket 104 comprises a condyle portion 120. A distal surface 121 of the socket is also shown. The condyle portion 120 is a part of the socket surrounding the femoral condyles when the prosthesis is in use. In figure 5, the hinges 108 are shown positioned laterally and medially of the condyle portion 120, with a centre of rotation 110 positioned through the centre of the femoral condyles, to approximate the anatomical centre of rotation of the knee.

Figure 6 shows a prosthesis 600 for a through-knee amputee comprising a locking mechanism. The prosthesis 600 comprises a proximal limb portion and a distal limb portion, shown generally by the numerals 102 and 106. The proximal limb portion 102 comprises a socket 104. The socket 104 is shaped to receive the upper leg limb of a through-knee amputee. The proximal limb portion 102 and a distal limb portion 106 are arranged to rotate around a single axis of rotation 110 between them. The proximal limb portion 102 and a distal limb portion 106 are joined by at least two hinges to enable rotation around the single axis of rotation 110. In embodiments, the hinges may be positioned in opposed lateral positions either side of the socket 104, as shown in figure 6.

The prosthesis 600 comprises a locking mechanism to lock the prosthesis in a fixed position. The prosthesis comprises a locking element 204 movably attached to the distal limb portion 106. The locking mechanism may comprise a recess 202 fixedly connected to the proximal limb portion 102. In embodiments, the locking element 204 may alternatively be movably attached to the proximal limb portion 102 and the recess fixedly attached to the distal limb portion 106. The locking element is arranged to engage with the recess 202 to lock the proximal limb portion 102 and the distal limb 106 portion in a fixed position.

In the embodiment shown in figure 6, the locking element is mounted on a moveable member 208. The movable member is arranged to move within and relative to a member 209 of the distal limb portion 106. In the embodiment of figure 6, the movable member 208 is arranged to move approximately parallel to the longitudinal axis of the distal limb portion 106. The movable member 208 is biased by a locking biasing means 206. The locking biasing means 206 is arranged to bias the locking element 204 out of recess 202 in the distal direction, as shown by arrows A. A foot portion or other ground contacting portion 210 is arranged at the distal end of the movable member 208. When a force is applied to the ground contacting portion 210, and the locking element 204 is aligned with the recess 202, e.g. when in a standing position, the movable member 208, and therefore the locking element 204 is urged against the bias and into the recess 202.

When in use, the prosthesis 600 can move in flexion and extension during walking. When the amputee is in a standing positon, the prosthesis is aligned so that the engagement element is positioned over the recess. In this position, the amputee can transfer a portion of their body weight through the prosthesis. The increased load is transferred via the socket 104, and opposed by contact of the foot portion 210 with the ground. This causes the locking biasing means 206 to compress so that the locking element 204 is engaged with the recess 202, locking the prosthesis in a fixed position. This arrangement may improve stability in the standing position, allowing the amputee to transfer weight onto the prosthesis without it flexing. This may also reduce the energy required by the amputee to maintain a standing position. In the embodiment of figure 6, the locking element 204 is moved into the recess 202. Therefore, in the standing position the load from the body-weight of the amputee may be transferred through the socket 104 via movable member 208 to the ground contacting portion (e.g. a foot portion) 210, rather than via the hinges. This may reduce the load on the hinges in the standing position and reduce wear on the hinges. When the amputee reduces the load through the prosthesis 200, the locking biasing means 206 will move the locking element 204 out of the recess 202, allowing flexion of the prosthesis 200.

The locking mechanism is not limited to the locking mechanism arrangement of the embodiment shown in figure 6. In the embodiment shown in figure 4, the contact member 112 is shown comprising a recess 202 into which an engagement element 114 can enter to lock the proximal limb portion 102 and the distal limb 106 portion in a fixed position. In this embodiment, the engagement element 114 may be considered as the locking element. When the prosthesis is in or close to extension, the engagement element/locking element may be positioned within the recess 202. The anterior lip of the recess may prevent any further extension or hyper extension of the prosthesis, and the posterior lip of the recess may resist flexion of the prosthesis. The posterior lip of the recess may be shaped so that with sufficient force of flexion, the engagement element/locking element 114 may move out of the recess 202, allowing further flexion. This arrangement may improve stability in the standing position, allowing the amputee to transfer weight onto the prosthesis. This may reduce the energy required by the amputee to maintain a standing position. In the embodiment of figure 4, the engagement element/locking element 114 is biased into the recess, therefore when in the standing position, some of the load from the body-weight of the amputee may be opposed by the biased engagement element/locking element 114, reducing load on the hinges. In embodiments, the locking element may engage with the recess to lock the proximal limb portion and the distal limb portion in a fixed position when a weight-bearing load is transferred through the prosthesis. The locking element may also disengage from the recess to unlock the proximal limb portion and the distal limb portion when a weight-bearing load is unloaded from the prosthesis. In embodiments, the engagement element may also be the locking element. In embodiments, the recess may be comprised as part of the contact member.

In other embodiments, the recess may not be comprised as part of the contact member, thus the contact member need not be an essential component of the locking mechanism. Similarly, a prosthesis may comprise a locking element that is not also an engagement element. Figure 7 shows an embodiment prosthesis 300 comprising an alternative locking mechanism. The prosthesis comprises a proximal limb portion and a distal limb portion. The socket 104 of the proximal limb portion 102 comprises a slot 309 arranged parallel to the longitudinal axis of the proximal limb portion. The hinges are arranged to displace along the length of the slot 309. Locking biasing means 206 are arranged to bias the socket in the proximal direction relative to the distal limb portion, i.e. bias the hinges towards the distal portion of the socket. In the embodiment shown, a locking element 204 is arranged to move with the socket 104 and to cooperate with a recess 202 mounted to the distal limb portion. In alternative embodiments, the recess 202 may be arranged to move with the socket and the locking element 204 mounted to the distal limb portion.

When in use, the prosthesis 300 can move in flexion and extension during walking. When the amputee is in a standing positon, the prosthesis is aligned so that the locking element 204 is positioned over the recess 202. In this position, the amputee can transfer a portion of their body weight through the prosthesis. The increased load is transferred via the socket 104, and opposed by the distal limb portion via contact with the ground. This causes the locking biasing means 206 to compress so that the hinges move within the slot 309, causing the socket to move towards the recess 202. The locking element 204 is moved to engage with the recess 202, locking the prosthesis 300 in a fixed position.

In the standing position the load from the body-weight of the amputee may be transferred through the socket to the ground contacting portion 210, through the locking element 204 rather than through the hinges. This may reduce the load on the hinges in the standing position and reduce the wear on the hinges. When the amputee reduces the load through the prosthesis 300, the locking biasing means 206 will move the locking element 204 out of the recess 202, allowing flexion of the prosthesis 300. The arrangement of figure 7 may also incorporate a contact member and engagement element as shown in figure 2, or the locking element 204 may function also as an engagement element using a similar principle as shown in figures 8 or 9.

Figure 8 shows an embodiment prosthesis 400. The prosthesis comprises a proximal limb portion 102 and a distal limb portion 106. The proximal limb portion 102 comprises a socket 104 and a contact member 112. The contact member further comprises a recess 202. The distal limb portion 106 comprises a moveable member 208 arranged to move relative to the main body of the distal limb portion 106 and parallel to the longitudinal axis of the distal limb portion 106. The movable member 208 moves through a member 209 of the distal limb portion. The distal limb portion comprises a locking biasing means 206 arranged to bias the movable member 208 in the distal direction. The engagement element 114 is mounted to the movable member and can move parallel to the longitudinal axis of the distal limb member 106 in relation to the moveable member 208. The engagement element is biased towards the contact member 112 by a biasing means 116. The engagement element 114 also functions as a locking element as described herein. In use, as the prosthesis 400 moves from a position of flexion towards extension, the displacement of the engagement element 114 against the bias transfers energy from the movement of the distal limb portion in relation to the proximal limb portion, into the biasing means 116. As the limb is moved towards extension, the engagement element 114 is displaced downwards against the biasing means 116, causing work to be done against the biasing means 116. The prosthesis 400 can move in flexion and extension during walking. When the amputee is in a standing positon, the prosthesis is aligned so that the engagement element 114 is positioned over the recess 202. In this position, the amputee can transfer a portion of their body weight through the prosthesis. The increased load is transferred via the socket 104, and opposed by contact of the ground contacting portion 210 with the ground. This causes the locking biasing means 206 to compress so that the engagement element 114 is engaged with the recess 202, locking the prosthesis in a fixed position. When the amputee reduces the load through the prosthesis 400, the locking biasing means 206 will move the locking element 204 out of the recess 202, allowing flexion of the prosthesis 400.

The biasing means 116 may be more compliant than the locking biasing means 206. Therefore, when the proximal 102 and distal portions 106 of the prosthesis 400 are in a configuration close to extension, biasing means 116 may be in a positon of maximum compression, and the locking biasing means 206 may be uncompressed or minimally compressed. When the proximal and distal portions of the prosthesis 400 are in a configuration of full extension but unweighted, the engagement element 114 may engage with the recess 202 via the action of the biasing means 116. However, in this unweighted configuration the engagement element 112 may be disengaged from the recess 202 with a flexion force applied to the prosthesis 400 that is sufficient to overcome biasing means 116. When the proximal and distal portions of the prosthesis are in a configuration of full extension but are weighted by the user's body weight, displacement of the moveable member 208 against the locking biasing means 206 may move the biasing means 116 and engagement element 114 closer to the recess 202, so that the engagement element 114 cannot be displaced out of the recess 202 by applying a flexion force to the prosthesis 400. Any compatible combination of locking mechanism and contact member/engagement element arrangements disclosed herein are envisioned as part of the present disclosure.

Figure 9 shows an alternative embodiment prosthesis 500. The prosthesis 500 comprises a contact member 112 and engagement element 114 arranged to function in a manner similar to the embodiment of figure 1 . The prosthesis also comprises a locking mechanism 202, 204 positioned laterally to the contact member 112 and engagement element 114, and functionally separated therefrom.

Figure 10 shows an embodiment members which comprises part of the distal limb portion. The members may be Y- or U- shaped as shown in figures 10 A-C. Y- or U- shaped member may be connected to at least two hinges. The members may comprise arms which connect to the hinges. The arms may be adjustable in length allowing for easy adjustment of the prosthesis to proportions and alignment of the amputee's opposing leg. In embodiments, the engagement element 112 and/or locking element 204 may be mounted to the Y- or U- shaped member. In embodiments, the movable member 208 may be movable through the Y- or U- shaped member.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word 'comprising' does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms "a" or "an," as used herein, are defined as one, or more than one. Also, the use of introductory phrases such as "at least one" and "one or more" in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an." The same holds true for the use of definite articles. Unless stated otherwise, terms such as "first" and "second" are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

Unless otherwise explicitly stated as incompatible, or the physics or otherwise of the embodiments, example or claims prevent such a combination, the features of the foregoing embodiments and examples, and of the following claims may be integrated together in any suitable arrangement, especially ones where there is a beneficial effect in doing so. This is not limited to only any specified benefit, and instead may arise from an "ex post facto" benefit. This is to say that the combination of features is not limited by the described forms, particularly the form (e.g. numbering) of the example(s), embodiment(s), or dependency of the claim(s). Moreover, this also applies to the phrase "in one embodiment", "according to an embodiment" and the like, which are merely a stylistic form of wording and are not to be construed as limiting the following features to a separate embodiment to all other instances of the same or similar wording. This is to say, a reference to 'an', One' or 'some' embodiment(s) may be a reference to any one or more, and/or all embodiments, or combination(s) thereof, disclosed. Also, similarly, the reference to "the" embodiment may not be limited to the immediately preceding embodiment. Unless otherwise stated, an object which is said to extend in a particular direction is to be construed as having a component of a directional vector that extends in said direction and does on preclude the extension in alternative directions.

The foregoing description of one or more implementations provides illustration and description, but is not intended to be exhaustive or to limit the scope of the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of various implementations of the present disclosure.

LIST OF REFERENCES

100 Prosthesis

200 Prosthesis

300 Prosthesis

400 Prosthesis

500 Prosthesis

600 Prosthesis

102 Proximal limb portion

104 socket

120 condyle portion of socket

121 distal surface of the socket

309 slot

106 distal limb portion

108 hinges

110 axis of rotation

209 member of the distal limb portion

112 contact member

118 movement stop 119 movement stop

114 engagement element

116 biasing means

202 recess

204 locking element

206 locking biasing means

208 movable member

210 ground contacting portion

301 longitudinal axis of proximal portion

302 longitudinal axis of distal portion

The following section of the description consists of numbered paragraphs simply providing disclosure already described herein. The numbered paragraphs in this section are not claims. The claims are set forth below in the later section headed "claims".

1. A prosthesis (300, 400, 500, 600) for a through-knee amputee, the prosthesis comprising: a proximal limb portion (102) comprising a socket (104) to receive the femur of a through- knee amputee; a distal limb portion (106); at least two hinges (108) to connect the proximal limb portion (102) to the distal limb portion

(106) to rotate around a single axis of rotation (1 10); the prosthesis comprising a locking mechanism to lock the proximal limb portion and the distal limb portion in a fixed position. 2. A prosthesis (300, 400, 500, 600) according to numbered statement 1 , wherein the locking mechanism comprises

a recess (202) fixedly connected to one of the proximal limb portion (102) or the distal limb portion (106); and a locking element (204) movably attached to the other of the proximal limb portion (102) or the distal limb portion (106);

wherein the locking element (204) engages with the recess (202) to lock the proximal limb portion (102) and the distal limb (106) portion in a fixed position.

3. A prosthesis (300, 400, 500, 600) according to numbered statement 2, wherein the locking element (204) engages with the recess (202) to lock the proximal limb portion (102) and the distal limb portion (106) in a fixed position when a weight-bearing load is transferred through the prosthesis (300).

4. A prosthesis (300, 400, 500, 600) according to numbered statement 2 or 3, wherein the locking element (204) disengages from the recess (202) to unlock the proximal limb portion (102) and the distal limb portion (106) when a weight-bearing load is unloaded from the prosthesis.

5. A prosthesis (400, 500) according to any of numbered statements 1 to 4, wherein the recess (202) is comprised as part of the contact member (1 12).

6. A prosthesis (400, 500) according to any of numbered statements 1 to 5, wherein the

engagement element (114) is the locking element (204).

7. A prosthesis (300, 400, 500, 600) according to any of numbered statements 1 to 6, wherein the locking element (204) is biased away from the recess (202) by a locking biasing means (206).

8. A prosthesis (400, 500, 600) according to any of numbered statements 1 to 7, wherein the distal limb portion comprises a movable member (208) configured to move relative to the distal limb portion (106) when a weight-bearing load on the prosthesis is applied or removed.

9. A prosthesis (300) according to any of numbered statements 1 to 7, wherein the proximal limb portion comprises a socket configured to move relative to the distal limb portion (106) when a weight-bearing load on the prosthesis is applied or removed. 10. A prosthesis (300) according to numbered statement 9, wherein the socket comprises a slot (309).

1 1. A prosthesis (300, 400, 500, 600) according to any of numbered statements 1 to 10, wherein the socket (104) comprises a condyle portion (120) to locate the femoral condyles of a through- knee amputee, and wherein the at least two hinges (108) are positioned laterally and medially of the condyle portion (120).

12. A prosthesis (300, 400, 500, 600) according to any to any of numbered statements 1 to 11 , wherein distal limb portion comprises a Y- or U- shaped member connected to the two hinges (108). 13. A prosthesis (300, 400, 500, 600) according to numbered statement 12, wherein the engagement element (114) and/or locking element (204) are connected to the Y- or U- shaped member. 14. A prosthesis (400, 500, 600) according to numbered statement 12 or 13, wherein the movable member (208) is movable through the Y- or U- shaped member.

Claims

1. A prosthesis (100, 200, 400, 500) for a through-knee amputee, the prosthesis comprising: a proximal limb portion (102) comprising a socket (104) to receive the femur of a through- knee amputee; a distal limb portion (106); at least two hinges (108) to connect the proximal limb portion (102) to the distal limb portion (106) to rotate around a single axis of rotation (110); a contact member (112) connected to one of the proximal limb portion (102) or the distal limb portion (106); an engagement element (114) connected to the other of the proximal limb portion (102) or the distal limb portion (106); wherein the engagement element (112) and the contact member (112) are biased towards each other; and wherein the contact member (112) is configured so that when the proximal limb portion (102) and the distal limb portion (106) undergo extension from a position of flexion, the contact member (112) contacts the engagement element (114) to displace the engagement element (114) against the bias.

2. A prosthesis according to claim 1 , wherein the contact member (112) comprises an elongate portion with a region of increasing thickness along the length of the elongate portion.

3. A prosthesis (100, 200, 400, 500) according to any preceding claim, wherein the engagement element (114) comprises a roller.

4. A prosthesis (100, 200, 400, 500) according to any preceding claim; wherein the engagement element (114) is biased against the contact member by a biasing means (116).

5. A prosthesis (100, 400, 500) according to any preceding claim, wherein the contact member (112) is attached to or integrated into a distal portion of the socket.

6. A prosthesis (100, 200, 400, 500) according to any preceding claim wherein the engagement element (114) is connected to the distal limb portion (106) and designed to move in a direction parallel to a longitudinal axis of the distal limb portion.

7. A prosthesis (100, 200, 400, 500) according to any preceding claim, wherein the contact member comprises one or more movement stops (118) to limit the range of rotation of the distal limb portion (106) relative to the proximal limb portion (102).

8. A prosthesis (100, 200, 400, 500) according to any preceding claim, wherein the socket (104) comprises a condyle portion (120) to locate the femoral condyles of a through-knee amputee, and wherein the at least two hinges (108) are positioned laterally and medially of the condyle portion (120).

9. A prosthesis (400, 500) according to any preceding claim, comprising a locking mechanism to lock the proximal limb portion and the distal limb portion in a fixed position.

10. A prosthesis (400, 500) according to claim 9, wherein the locking mechanism comprises

wherein the locking element engages (204) with the recess (202) to lock the proximal limb portion (102) and the distal limb (106) portion in a fixed position.

1 1. A prosthesis (400, 500) according to claim 10, wherein the locking element (204) engages with the recess (202) to lock the proximal limb portion (102) and the distal limb portion (106) in a fixed position when a weight-bearing load is transferred through the prosthesis (300).

12. A prosthesis (400, 500) according to claim 10 or claim 11 , wherein the locking element (204) disengages from the recess (202) to unlock the proximal limb portion (102) and the distal limb portion (106) when a weight-bearing load is unloaded from the prosthesis (300).

13. A prosthesis (100, 400) according to any of claim 9 to claim 12, wherein the recess (202) is comprised as part of the contact member (1 12).

14. A prosthesis (100, 400) according to any of claim 9 to claim 13, wherein the engagement element (1 14) is the locking element (204).

15. A prosthesis (400, 500) according to any of claim 9 to claim 14, wherein the locking element (204) is biased away from the recess (202) by a locking biasing means (206).

16. A prosthesis (400, 500) according to any of claim 9 to claim 15, wherein the distal limb portion comprises a movable member (208) configured to move relative to the distal limb portion (106) when a weight-bearing load on the prosthesis (300) is applied or removed.

17. A prosthesis (400, 500) according to claim 16, wherein the distal limb portion (106) comprises a ground contacting portion (210), and the ground contacting portion (210) is connected to the movable member (208).

18. A prosthesis (400, 500) according to claim 16, wherein the proximal limb portion (102)

comprises the movable member, and the movable member is configured to move relative to the proximal limb portion (102) when a weight-bearing load on the prosthesis (400) is applied or removed.

19. A prosthesis (400, 500) according to any of claim 16 to claim 18, wherein the engagement element (204) is connected to the movable member (208) and the engagement element (204) engages with the recess (202) to lock the prosthesis when a weight-bearing load is applied to the prosthesis (200, 300, 400).

20. A prosthesis (400, 500), according to any of claim 16 to claim 19, wherein the movable

member (208) is biased by the locking biasing means (206).

21. A prosthesis (100, 200, 400, 500) according to any preceding claim, wherein distal limb portion comprises a Y- or U- shaped member connected to the two hinges (108).

22. A prosthesis (100, 200, 400, 500) according to claim 21 , wherein the engagement element (1 14) and/or locking element (204) are connected to the Y- or U- shaped member.

23. A prosthesis (400, 500) according to claim 21 or claim 22, when dependent on moveable any of claims 16 to 20, wherein the movable member (208) is movable through the Y- or U- shaped member.