WO2015103506A1

WO2015103506A1 - Dynamic adjustable socket for prosthetics

Info

Publication number: WO2015103506A1
Application number: PCT/US2015/010079
Authority: WO
Inventors: Avinoam Livni; Shuki Wolfus; Ofri WOLFUS
Original assignee: Easyfit Orthopedics Ltd.; Klein, David
Priority date: 2014-01-03
Filing date: 2015-01-04
Publication date: 2015-07-09

Abstract

A prosthesis includes a support member (12) adapted to support a limb of a body. The support member includes adjustable cells (16) each capable of bearing a portion of a weight of the limb. In one embodiment, each of the cells is fillable with a fluid. A distributor (40) is in fluid communication with a source of fluid and the cells. The distributor includes a rotor (46) selectively in fluid communication with a subset of the cells while simultaneously sealing fluid flow to a remainder of the cells.

Description

DYNAMIC ADJUSTABLE SOCKET FOR PROSTHETICS

FIELD OF THE INVENTION

The present invention relates generally to prosthetic devices, and in particular to a dynamic adjustable socket for prosthetic devices.

BACKGROUND OF THE INVENTION

Today's prosthetic solutions for below and above-knee amputees exhibit significant differences between foot and knee, and socket technologies. Research and development effort is mostly invested in foot and knee technologies resulting with advanced solutions that incorporate advanced materials, energy observing and energy release optimization, computer controlled components and artificial intelligent algorithms. Feet and knees are basically manufactured as stand-alone production-line components allowing the amputee to select such components that best fit his/her activity level and way of life.

Socket technology, however, falls behind dramatically. While advanced materials are constantly being searched for and integrated in socket solutions, the socket itself has remained basically a static device for ages. Prosthetic sockets are still one-by-one custom- made products, which fit only to the individual amputee for whom it was made. The socket is in principle a "negative copy" of the amputee's stump with minor shape variations intended to change weight distribution and transfer more forces to selected tendons and tissues which better carry higher loads. Therefore, the socket reflects a "snapshot" of the residuum leg at the time it was built.

The stump, being a living biological organ, is constantly subjected to changes. In the short term, the stump goes through volumetric diurnal changes that depend on the amputee's activity (sleeping, sitting, walking, etc.), on body fluids state, temperature, blood pressure and other biological and environmental parameters. In addition, momentary activity changes the forces and forces distribution around the stump. For example, it is clear that the forces applied to the stump during running are much higher and differently distributed than forces applied while sitting. In the long term, parameters as age, seasonal changes, time elapsed from the trauma, nutrition and weight variations, loss and gain of muscle and bone tissues, etc., also affect the stump, which goes through volumetric and shape changes.

The socket, being a static device, does not react to any of the above mentioned changes in the stump; hence the fit between the socket and the stump is lost. To compensate for these changes, the amputee would add/remove socks at various numbers and thicknesses and replace liners. However, such additions, being more or less homogeneous in their thickness, may lead to inefficient force distribution and may even lead to skin irritations, rush and sores that badly damage quality of life. Sooner or later the misfit between the socket and stump would require the replacement of the socket.

SUMMARY OF THE INVENTION

The present invention seeks to provide a dynamic socket solution, as described more in detail herein below. The socket adjusts itself to short and long term stump variations to ensure maximal comfort at the required momentary grip. For achieving this purpose, the socket is divided into 'pixels' (also called cells) where each pixel measures and adjusts the local pressure at the interface between the socket and the stump.

The invention allows manufacturing sockets as stand-alone production-line products, similar to the state-of-the-art of artificial feet and knees. By making the interface between the socket and the stump dynamically and automatically adjustable, the external socket envelope could be made to pre-defined sizes and lengths.

In another embodiment of the invention, forced-air circulation is implemented between pixels. Such air circulation reduces sweat and skin problems and improves the quality of life of the amputee.

Another embodiment of the invention enables remote programming and control of the socket interface and account for special needs and requirements of the individual amputee.

Another embodiment of the invention enables programmable planned pressure variations of individual or one or more groups of pixels so that to allow local and global massage of the stump and improve blood flow.

Another embodiment of the invention collects dynamic data from the user, to process and analyze the way a user wears his/hers prosthetics and offer ways to improve such use. In particular, this can improve the way the amputee walks, climbs steps, runs, etc., thus prevent future orthopedic problems and aches.

Another embodiment secures the prosthetic leg and prevents slipping for all activities of the amputee. The dynamic socket of this invention provides at all times the minimal grip force that secures the socket, yet provides maximal comfort. The grip is tight enough to prevent rotational motion of the socket relative to the stump. Another embodiment increases the range of motion of the amputee's leg by eliminating sections of the socket that today limit such range.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

Figs. 1A and IB are simplified pictorial and side-view illustrations, respectively, of a dynamic prosthetic socket, constructed and operative in accordance with a non-limiting embodiment of the present invention.

Fig. 2 is a simplified illustration of a fluid-actuated pixel, in accordance with a non- limiting embodiment of the present invention.

Fig. 3 is a simplified illustration of a fluid filling/exhaust system in accordance with an alternative embodiment of the invention.

Figs. 4A and 4B are simplified side-view and top-view illustrations, respectively, of a mechanically-actuated pixel, using rotating cams, in accordance with a non-limiting embodiment of the present invention.

Figs. 5A and 5B are simplified side-view and top-view illustrations, respectively, of mechanically-actuated pixel, using sliding cams, in accordance with a non-limiting embodiment of the present invention.

Fig. 6 is a simplified illustration of a general mechanically-actuated pixel used in the prosthetic socket, in accordance with a non-limiting embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to Fig. 1, which illustrates a prosthetic socket, constructed and operative in accordance with a non-limiting embodiment of the present invention.

The above objectives are to be achieved by creating a prosthetic socket for above and below knee amputees where a "smart" interface resides in a layer between the rigid external socket and the residual limb. This interface may replace socks and/or liners, which are used as an interface in today's socket solutions. The interface of this invention is capable of dynamically sensing local forces, pressure distribution, other pre-defined biological parameters and the activity level of the amputee, and reacting to change the local force distribution within the interface in a way that applies minimum force to ensure a safe grip of the socket, yet maximum comfort to the amputee. The ability to sense and react to local force distribution at the residual limb is achieved by making such interface of individual cells (pixels), each controlled by algorithms that determine the required spatial and temporal force distribution necessary for optimal grip and comfort, depending on momentary biological and physical states of the stump. In some embodiments or protocols of operations, pixels may be grouped, electrically or logically, and controlled in group units.

Figs. 1A-1B illustrate a prosthetic leg 10 that includes a socket 12 made in a regular shape (cylindrical in this example), without adapting its form to the contours of a specific residual leg. A smart interface 14 is responsible for the adaption to the specific stump shape and is shown as an array of pixels 16. Each individual pixel or cell 16, or group of pixels 16, is capable of providing data to a control unit (shown in Fig. 3) about the local biological and physical parameters sensed and adapt its volume and applied force following commands of such control unit. Pixels 16 may sense and react separately or may be grouped together by the logics to form a wider area of pixels. The spatial resolution is defined by the number of such pixels, determined by the application requirement and by production and cost considerations. Also shown in Figs. 1A-1B are a support rod 18 and a prosthetic foot 20, not referred to in the framework of the present invention.

In one embodiment, the pixel 16 includes a sensor that senses information related to the cell and is in communication with the control unit to provide feedback to the control unit. The control unit processes sensed data from the sensor to modify a height of the cell so as to dynamically adjust a weight-bearing capability of the cell. An example of a sensor is a force sensor 15, such as a load cell, that senses forces on the pixel. The load cell may be oriented to sense vertical forces, horizontal forces or other oriented forces. The forces may be the static weight of the limb or dynamic forces felt during motion of the limb. In another example, the pixel 16 may include an accelerometer 17 that senses accelerations in any of 3 mutually perpendicular axes. The sensed data from the force sensor 15 and/or accelerometer 17 are processed by the control unit to modify the height of the pixel so as to dynamically adjust the weight-bearing capability of the pixel, e.g., to provide a softer or harder support to the limb, or more yielding or less yielding (without changing hardness or softness), depending on the particular need and user requirements. For example, if the control unit senses an increase in the force on the limb or an increase in the acceleration away from the limb, the control unit may send a signal to the pump to increase the height of cell 16 to bear the added force on the cell. Conversely, if the control unit senses a decrease in the force on the limb or an increase in the acceleration on the limb, the control unit may send a signal to the pump to decrease the height of cell 16 to adjust to the decreased force on the cell.

In other embodiments, the pixel 16 includes a biological activity sensor, such as but not limited to, moisture sensors (for sensing sweat, for example), temperature sensors, gyros, heartbeat sensors, or other mechanical and/or biological sensors and the like. The sensors may be located inside the cell or outside the cell, e.g., as a separate unit or inside the control unit. The control unit can process the sensed data to dynamically adjust the weight-bearing capability of the pixel or possibly to provide a warning signal of too much stress or other dangerous situations.

Fig. 2 schematically illustrates a fluid-actuated pixel 16 in one embodiment of the invention. In this embodiment, each pixel 16 is made of two surfaces, a first surface 22 (e.g., limb support surface 22) and a second surface 24 peripherally connected and sealed by a flexible peripheral member 26, such as but not limited to, a bellows (such as a metal welded bellows) or a collapsible and expandable ring (such as a flexible band made of plastic, metal, cloth, natural or synthetic rubber, for example). The first and second surfaces may be, without limitation, a fixed base and a moving plate. In one example, the flexible peripheral member 26 may be placed between a portion of the prosthesis and a silicone layer - the prosthesis and the silicone layer are the first and second surfaces. The flexible peripheral member 26 is filled with pressurized fluid 28 (gas or liquid, such as air or water, without limitation), which allows the pixel 16 to change its volume and dynamically fit in the gap between the socket and the residuum leg. The flexible peripheral member 26 is in fluid communication with a pump 30 via a tube 32. Pump 30 pumps more fluid to flexible peripheral member 26 (from a fluid reservoir 34, such as a liquid canister or simply the atmosphere) or draws fluid from flexible peripheral member 26, thereby increasing or decreasing the pixel volume and thus changing the pixel's height and local force it applies to the stump. It is noted that the term "pump" refers to any device for moving fluid and includes, without limitation, a high pressure chamber (i.e., at a pressure higher than the current pressure in the cell) from which fluid flows to the cell. Pump 30 can be any suitable pump, which is readily commercially available, such as but not limited to, a linear piston device driven by a micro-motor and connected to the tube feeding the pixel. Utilizing a lead screw and gear system, the volume of the piston can be varied to supply/absorb gas/liquid to/from the pixel and determine the pressure it applies to the stump. Another example is a peristaltic pump in which a gear motor controls the amount of gas/liquid transferred between a squeezable silicone tube and the pixel. These are just two examples of many kinds of applicable pumps.

Fig. 3 displays schematically an example for a mechanism controlling the pressure in individual pixels for use with the fluid-actuated pixels. Although Fig. 3 is particularly relevant for gas use, as stated before, the fluid-actuated pixels may be pumped with liquid. In Fig. 3, a compressed gas reservoir 34 is used for supplying gas per demand to all pixels. In one embodiment, reservoir 34 may contain liquid C0₂, which evaporates immediately as is leaves the storing reservoir.

The gas pressure is reduced to a pre-determined level (such as by a pressure reducer P.R.) and stored in an optional intermediate reservoir 36 feeding a central gas line 38, which contains one or more components (e.g., valves) for controlled venting and filling. The main line 38 leads to at least one distributor 40, which connects between the individual pixels 16 and the main gas line 38. When connected, the distributor 40 forms a continuous gas path between a selected pixel 16 and the main line 38 while unselected pixels remain sealed and maintain their individual gas fill level. In the embodiment shown in Fig. 3, the distributor 40 is a rotating body with gas ports 42 connected to individual pixels 16 on one side and a connection 44 to the main line 38 on another side. In this example, a stepper motor 46 rotates the distributor 40, enabling the selection of any pixel 16.

A control unit 50 is in communication with the distributor 40, motor 46, pixels 16 and any of the flow control components (e.g., valves), either by wired or wireless connection.

Also shown in Fig. 3 is an optional split of the main gas line 38 for feeding two different main pressure levels to the distributor 40. A higher-pressure line 38H may be used for a quick fill of pixels and a lower-pressure line 38L may be used for fine pressure/vent pulses. When a specific pixel connects to the main line 38 via the distributor 40, its pressure is measured, a decision is obtained at control unit 50 whether a pressure, vent or no pulse is required and the control unit 50 then activates the corresponding valve for a period of time necessary for generating the required pressure pulse.

Figs. 4A-4B illustrate an embodiment of a mechanically-actuated pixel, a rotating cam mechanism. In Fig. 4A, a side view is shown. Two rotating cam disks 52 (such as with a triangular cross-section to give a wedge or other cam effect) are rotatingly mounted on a base plate 54 (each disk rotates around its central axis). The disks 52 may be rotated by a motor 56 (e.g., a gear motor). For example, without limitation, the disks 52 are connected via mechanical links 58 to a hinged nut 60 connected in turn to motor 56. The rotation of the hinged nut 60 pushes and pulls the links 58 and rotates the disks 52. A top plate 62 to which push pins 64 are connected is positioned over the rotating disks array. When the disks 52 rotate, the push pins 64 follow the profile of the disk cross section and the top plate 62 moves up and down thus controlling the height of the pixel. Return springs 66 and guide pins 68 maintain contact between the push pins 64 and the disks 52 and prevent the top plate 62 from sliding sideways. The top view of the cell is shown in Fig. 4B and the rotating mechanism and the mechanical links are shown.

The embodiment described in Figs. 4A-4B uses two rotating disks. However, it is clear that such embodiment may be realized with any number of rotating disks and other kinds of cams. The rotating cams mechanism requires no filling medium. Specifically, neither gas nor liquid is required for varying the force applied by the pixel. In this embodiment, each pixel (or group of pixels) is activated by at least one motor controlled by the control unit. Several motors may be activated simultaneously; hence fast and accurate response of the entire array of pixels can be achieved.

Figs. 5A-5B illustrate another embodiment of a mechanically-actuated pixel, a sliding cam mechanism. Shown in Fig. 5A is a side view of the pixel where sliding wedges 72 having a triangular cross-section move one on top of each other to alter the space between two plates 74 and 76 and thus determine the height of the pixel and the force it applies to the stump. Wedges 72 may slide in tracks 77 (Fig. 5B) so as to prevent any unwanted lateral movement. As seen in Fig. 5B. a lead screw 78 may be connected at one end to a gear motor 80; the lead screw 78 is threaded through the pair of dual sets of wedges 72. Upon rotation of the lead screw 78, the upper dual wedges slide on the lower wedges upward or downward, depending on the direction of rotation. The slope of the wedges profile and the thread of the lead screw determine the gear ratio between the number of rotations and the pixel height variation.

The embodiments of Figs. 4A-5B are examples for the general case of a mechanical pixel of variable volume, which may be actuated by an actuator, such as, but not limited to, a micro motor. In Fig. 6, the general concept is described. The pixel 16 is a variable height device, which fills the gap between a static socket wall 82 and the dynamic residual limb 84. The pixel height is varied utilizing an actuator 86 to compensate for the changes in the residual limb 84. The pixel 16 may be embedded at one end within the socket wall 82 or mounted on the wall in any other way. The moving end of the pixel may contain an elastic, high friction interface 88, which comes in contact directly with the skin (e.g. silicone compound). An alternative could be using a rigid end plate, which applies its force to an existing interface, such as silicone liner for example. The variable height device is controlled by actuator 86, which may include a force multiplying system (mechanical advantage devices). For example, the actuator 86 may be mechanically coupled to the device by means of a force gear ratio or other kinds of mechanical advantage devices, such as hydraulic or pneumatic force multiplication inside or outside the cell. Other actuators for mechanically- actuated pixels include, without limitation, telescopic poles, rods, bars or screws, miniature jacks, a simple screw, gears (these devices are of course other examples of mechanical advantage devices), The actuator is in communication with control unit 50, which calculates the local force distribution and determines the height of each pixel. As described above, one or more sensors provide feedback control to the control unit to adjust the cell in accordance with the sensed information.

Claims

CLAIMS What is claimed is:

1. A prosthesis comprising:

a support member adapted to support a limb of a body, said support member comprising a plurality of adjustable cells each capable of bearing a portion of a weight of said limb, each of said cells being fillable with a fluid; and

at least one distributor in fluid communication with a source of fluid and said cells, said at least one distributor being selectively in fluid communication with at least one of said cells while simultaneously sealing fluid flow to a remainder of the cells.

2. A prosthesis comprising:

a support member adapted to support a limb of a body, said support member comprising a plurality of adjustable cells each capable of bearing a portion of a weight of said limb, wherein each of said cells comprises a limb support surface and a non-fluid- actuated variable height device that adjusts a position of said limb support surface, and wherein said variable height devices are controlled by at least one actuator.

3. The prosthesis according to claim 2, wherein said variable height device comprises a wedge mechanism.

4. The prosthesis according to claim 2, wherein said variable height device comprises a movable cam mechanism.

5. The prosthesis according to claim 1 or claim 2, wherein at least one of said cells comprises a sensor that senses information related to the cell, said sensor being in communication with a control unit operative to process sensed information from the sensor to modify a height of the cell so as to dynamically adjust a weight-bearing capability of the cell.

6. The prosthesis according to claim 5, wherein said sensor comprises a force sensor.

7. The prosthesis according to claim 1, wherein said cell comprises a fluid-actuated pixel made of two surfaces peripherally connected and sealed by a flexible peripheral member filled with a pressurized fluid, said flexible peripheral member being in fluid communication with a pump.

8. The prosthesis according to claim 4, wherein said movable cam mechanism comprises at least one rotating cam.

9. The prosthesis according to claim 4, wherein said movable cam mechanism comprises at least one sliding cam.

10. The prosthesis according to claim 2, wherein said variable height device comprises a mechanical advantage device.

11. The prosthesis according to claim 5, wherein said sensor comprises an accelerometer that senses accelerations in any of three mutually perpendicular axes.

12. The prosthesis according to claim 5, wherein said sensor comprises a biological activity sensor.

13. The prosthesis according to claim 1 or claim 2, wherein said cell comprises a high friction interface for interfacing with a limb.