Patent Application
20210113356
The present invention relates to a socket for a prosthetic limb. In particular, the present invention relates to an adjustable socket for use with a lower limb prosthesis.
A prosthesis can be attached to a residual limb in the following manner. A hollow rigid socket is custom made from a moldable material to accommodate the shape of the residual limb. At the distal end of the socket there is an attachment for attaching the prosthetic device to the socket, such as a pyramid alignment interface. Many amputees use a soft flexible liner as an interface between the residual limb and the socket. Before inserting the residual limb into the socket the liner is donned on the residual limb. The liner provides a resilient cushioning layer to improve comfort for the user. Liners are typically made from an air impermeable material such as silicone or a thermoplastic elastomer gel. Some liners, whilst being made from air impermeable material, are perforated to allow for flow of fluid from the inner surface of the liner to the outer surface thereof.
An intimate fit is required between the residual limb, the liner and the socket. This close fit is required to prevent relative motion between the socket, liner and residual limb, to prevent irritation of the skin and other soft tissue of the residual limb. The intimate fit also better distributes forces on the residual limb when weight is applied to the prosthesis via the socket. For a lower limb prosthesis, this will occur when the prosthesis is in contact with the ground, for example when standing and during the stance phase of the gait cycle.
During the course of the day, there will be changes in the volume of an amputee's residual limb and its shape (due to movement of fluid and soft tissue). This variation depends on many factors, including but not limited to the individual residual limb's characteristics, medical conditioning, the environment and types of activity undertaken by the amputee, etc. For example, during walking the socket will exert varying pressure on the residual limb. When there is no activity, for example when the prosthetic limb is not worn and during the night, the original shape of the limb will be restored. It is also known that residual limb volume will change considerably when worn during the course of the day and with periods of activity and rest. In order to accommodate this volume variation the amputee may wear a plurality of socks over the liner (or next to skin, when a liner is not worn), which can be removed or supplemented during the course of the day in order to maintain a comfortable and effective fit between the residual limb and the socket. At present this adjustment of fit is based largely on the skill and judgement of the amputee. However, due to underlying health issues some amputees may experience sensory loss within the residual limb, which makes these adjustment decisions more difficult. It is therefore an aim of the present invention to overcome some of these difficulties.
Another way of accommodating the variation in the volume of the residual limb is by altering the size and shape of the socket or the internal cavity thereof.
US-A1-2006/009860 describes an adjustable prosthetic socket comprising a cup, a lateral wall, and a brim. The cup includes a lateral cutaway portion, a lower closed portion, and an upper open portion. The brim is adapted for adjustable mounting in said cup via said upper open portion while the lateral wall is adapted for adjustable mounting in said lateral cutaway.
US-A1-2013/218296 describes a socket and suspension system. Moving fluid in or out of an area between a liner and the socket causes the liner to push away from the socket wall or pull into the socket wall thereby changing the volume inside the socket.
US-A1-2015/119997 describes an adjustable prosthetic limb socket system having a partial rigid support, a non-elastic, flexible support and adjustment means.
WO-A1-2015/013560 describes an adjustable socket for a prosthetic limb including an adjustment mechanism to adjust a volume of the cavity to accommodate an increase or decrease in a volume of the user's residual limb.
WO-A1-2015/013506 describes an adjustable socket for a prosthesis including adjustable cells each capable of bearing a portion of a weight of the limb.
The present invention provides an improved adjustable prosthetic socket.
According to a first aspect of the invention, there is provided a prosthetic limb socket comprising:
The socket may be a transfemoral or knee disarticulation socket for a transfemoral or knee disarticulation residual limb respectively and the plurality of support portions may comprise:
The first support portion may extend around a medial portion of the circumference of the socket; the first panel may extend along an anterior lateral portion of the socket; the second panel may extend along a posterior lateral portion of the socket; and the second support portion may extend along a lateral portion of the socket.
The first and second panels may extend proximally beyond the second support portion.
The socket may be a transfemoral or knee disarticulation socket for a transfemoral or knee disarticulation residual limb respectively and the plurality of support portions may comprise first, second and third cantilevered support portions, the support portions defining between their lateral edges first, second and third windows. The plurality of adjustable panels may comprise first, second and third adjustable panels, each panel being disposed in one of the first, second and third windows. Alternatively, the socket may comprise fourth or fifth support portions, windows and adjustable panels.
The panels may comprise a rigid or semi-rigid outer shell and a resiliently compressible inner portion.
The inner portion may comprise a strip of ethylene-vinyl acetate.
In combination the support portions and panels may extend around the circumference of the socket.
The means for adjusting a radial position of the panels relative to the support portions may comprise a cord or cords traversing the support portions and the panels.
The cord is or the cords may be disposed on an outer surface of the support portions or embedded within an outer shell of the support portions.
The cords may comprise a first cord and a second cord.
The socket may further comprise means for drawing the cord or cords radially inwards.
The means for drawing the cord or cords radially inwards may comprise a ratchet mechanism.
The ratchet mechanism may comprise first and second ratchet reels, each ratchet reel drawing in one of the first and a second cords, the first and second cords being spaced distally and proximally of each other along the support portions.
The means for drawing the cord radially inwards may comprise a motor.
According to a second aspect of the invention there is provided a prosthetic limb socket comprising:
The means for adapting an interior volume of the support member may comprise one or more of: a rigid support member and a plurality of support portions as described above; a ski-boot type adjustable buckle and buckle hook; and one or more adjustable volume bladders.
The means for adapting a temperature within the support member comprise one or more of: a thermoelectric element; a fan; and an extraction port in a wall of the socket.
The sensors may sense one or more of: temperature; humidity; oxygen levels; pressure; shear/friction; bacteria; movement; proximity; and displacement.
The present invention will now be described by way of example only, and with reference to the accompanying drawings in which:
In particular, the first support portion 7 begins at the antero-lateral side of the socket 1, continues medially and posteriorly and ends at the lateral posterior side of the socket 1. The support portion 7 subtends an angle of around 240° to a central axis of the socket 1. In contrast to the support portion 7, the second support portion 9 which is opposite the first support portion 7, is only visible in
Since the first 7 and second b 9 support portions extend proximally from the distal base portion 5, they define between their lateral edges 7E, 9E windows 11A, 11P. One window 11A is a lateral anterior window and the other window 11P is a lateral posterior window. Disposed within the windows 11A, 11P are respective lateral anterior 13A and lateral posterior 13P adjustable panels. These panels 13A, 13P may be made of a rigid or a semi-rigid material. The lateral anterior 13A and lateral posterior 13P panels are generally shaped to correspond to the shape of the respective windows 11A, 11P, to substantially fill the windows, but are separate pieces to the rigid support member 3. As can be seen from
The outer shell 3S of the rigid support member 3 and the outer shells 13AS, 13PS of the lateral anterior 13A and posterior 13P adjustable panels are made of carbon fibre, glass reinforced plastic or another rigid material that can be molded to the shape of a residual limb. Alternatively, the rigid support member 3 and the outer shells 13AS, 13PS of the lateral anterior 13A and posterior 13P rigid panels may be manufactured from scans or casts of the residual limb using additive manufacturing technique, including both single and multimaterial techniques. The outer shells 3S, 13AS, 13PS are shaped to conform to the outer shape of the residual limb of the amputee following the standard technique used to form sockets, namely casting a negative cast around the residual limb, casting a second positive cast having the shape of the residual limb and using the positive cast to form the outer shells 3S, 13AS, 13PS. The outer shells 3S, 13AS, 13PS may be made by forming a single shell corresponding to the shape of the residual limb and then cutting out the anterior 13A and posterior 13P adjustable panels to leave behind the rigid support member 3, or by separately forming these three parts 3, 13A, 13B.
The panels and or other portions of the socket may also be made of adjustable structural materials for example based on material “jamming” principles. In such embodiment, the panel(s) consist of granular material contained in a bag, when the air contained within the bag is evacuated the granular material are brought together, “jamming” to create a rigid shape conforming to the interfacing structures (e.g. the residual limb and/or socket). Similarly, a few layers of socks each with fabrics woven in different direction and contained in an airtight bag would “jam” when air was evacuated from the said bag.
An internal flexible liner is disposed within the socket. The liner is made from a material such as Northvane® which is manufactured by North Sea Plastics® Ltd.
The lateral anterior 13A and lateral posterior 13P adjustable panels are held in position on the rigid support member 3 by means of a pair of cords or laces 15D, 15P traversing the lateral windows 11A, 11P. These cords serve as means for adjusting a radial position of the panels 13A, 13P relative to the support portions 7, 9. The cords 15D, 15P have the structure of a Bowden cable, having an inner cable which can move easily relative to a hollow outer cable housing which is fixed to the wall of the support portions 7, 9 and lateral rigid panels 13A, 13P. In particular, the cords comprise a first, proximal cord 15P and a second, distal cord 15D. The cords may also be actuated using, for example, electroactive polymers or shape memory materials. Aside from radial adjustment, the arrangement of cords may also be used to rotate and/or adjust the longitudinal or medial lateral position of the panels to better fit with the residual anatomy. This positional adjustment of the support panels is particularly important, for example, with a child socket and with a growing residual limb.
The proximal cord 15P passes around a partial circumference of a proximal portion of the socket 1 in the following manner. A proximal reel 17P (see
The distal cord 15D passes around a partial circumference of a distal portion of the socket 1 in a similar manner. A distal reel 17D (see
The proximal 17P and distal 17D reels serve as a means for drawing the cords 15P, 15D radially inwards. Each reel 17P, 17D includes a releasable ratchet mechanism for tightening and holding the cords 15P, 15D in place. Such ratchet mechanisms are produced by Boa Technology, Inc. and marketed under their Boa® closure system brand. In this manner the cords 15P, 15D can be tightened, locked in place and released during the course of the day as the amputee adjusts the interior volume of the socket 1. The amputee may make the adjustment, for example, for specific activities requiring more control or comfort. This may be a guided adjustment based on pressure/shear, circumferential measurements using for example a RAG (red, amber green) system, displayed in the liner using wearable electronics or wirelessly using a smart phone app. Alternatively the adjustment may be fully automated by actuating the cords which in turn alters the position of the adjustable panels 13A, 13B.
In use, when the proximal reel 17P is turned to tighten the proximal cord 15P, the proximal portion of socket 1 is drawn inwards around the trochanter of the femur. Similarly, when the distal reel 17D is turned to tighten the distal cord 15D, the distal portion of socket 1 is drawn inwards around the soft tissue at the end of the residuum.
In a further embodiment, instead of the cords 15P, 15D passing around and being tightened by manually tightenable reels 17P, 17D, a motor may be used to automatically or semi-automatically tighten the cords 15P, 15D. This tightening may be performed in response to signals received from sensors incorporated into the sockets, as is explained below.
In another embodiment (not shown), posterior support portion 68B and medial support portion 68B of
In another embodiment, posterior support portion 68B and medial support portion 68A are joined together into a single support portion that subtends an angle of around 140° to a central axis of the socket 71. The support portion curves outwards at its proximal end, thus providing a seating area and giving an amputee additional support. In this embodiment, the socket does not contain panel 69D shown in
In another embodiment, chords 70 can be used to control the position of some of the panels individually.
In another embodiment, any of the support portion 74A, 74C and 74D extend distally and join the distal portion of the socket 72. Any of the adjustable panels 73A, 73B, 73C and 73D may be removed and substituted with a closed, fixed strut.
In another embodiment, brim 77 may be split, so that it forms a discontinuous hoop. This enables adjusting the brim tightness through means of, for example, ratchets, Velcro® straps or chords.
In another embodiment, support portion 79 may be located at posterior-medial aspect of the socket. In this embodiment, there is no posterior-medial adjustable panel. The other elements of the socket remain the same as in
In another embodiment, brim 81 may be split at an arbitrary location, so that it forms a discontinuous hoop. This enables adjusting the brim tightness through means of, for example, ratchets, Velcro® straps or chords.
Although support portions 85 are rigid themselves, they are hinged around the dashed line 89. The hinging can be achieved in numerous ways:
The hinging permits controlling protrusion of support portions into the socket. This can be controlled with chord 88. This can be the same or different chord from that controlling adjustable panel 86.
In another embodiment, adjustable panel 86 can be attached to the distal portion of the socket 84 forming a support portion. The support portion is hinged around the same level as the other support portions 85A and 85B (i.e., around line 89). Methods of hinging are the same as listed above.
In another embodiment, support portions 85 extend further proximally, above an amputee's femoral condyles, and curve slightly towards the inside of the socket. This forms supra-condylar suspension, preventing the socket from falling off during swing. These “supracondyles” are hinged at the level of patella tendon, which can be achieved in the same fashion as described above. Therefore, the “supracondyles” can be brought in and out of the socket, providing more or less suspension. The action of bringing the “supracondyles” in and out of the socket (i.e. their actuation) can be achieved with chords, or other actuation methods described below.
In all embodiments, support portions may exhibit variable flexibility. Typically, the support portions would be more rigid distally and less rigid proximally. The variation in the socket flexibility can be achieved with the following methods:
In another embodiment, support portions may contain cut-ins, such as those presented in
Flexion sensors may be placed in the support portions. Flexion measurement may be used, for example, for feedback to the actuators flexing the support portions. An example of such a sensor is optical fibres that are woven into the layup of the support portion. In such sensors a beam of light is injected into the fibre and a detector is placed at the other fibre end. The transduction mechanism relies in the change of light beam properties (e.g., light wavelength), upon flexion of the strut, as measured by the detector.
The amputee's residuum could be suspended in the socket in a range of different ways.
With an inner liner 14—Such a liner allows for generation of vacuum and hence suspending the residuum with either suction or elevated vacuum methods. As an alternative, the liner could be made of a more flexible material and could be moulded over the support portions, thereby forming a single part with the rest of the socket.
With a regular silicone or gel liner and existing suspension techniques such as pin lock, magnetic lock, Velcro® lock, suction or vacuum suspension. In such case, the liner should feature control of the circumferential stretch, which should vary depending on the tissue viability of the amputee. Amputees with firm tissues would be fitted with more stretchy material (around the circumference). Amputees with more compromised, flaccid tissue, would be fitted with liners limiting the circumferential stretch. This is to ensure that once the pressure is applied through the adjustable panels to the stump, the tissue that is pushed away does not ‘bulge out’ through the socket ‘windows’ or through the fixed support portions. Therefore, a liner with limited circumferential stretch acts as a medium of ‘containing’ the tissue. This stretch may be selectively adjustable in different regions of the liner using actuatable threads, the stretch may also be measurable using stretch sensor, piezo resistive polymers etc.
With a ‘hammocking’ liner—Such a liner would be attached around the brim of the socket, and the residuum would be supported as if it was in a hammock. This concept is particularly applicable to the socket shown in
Both liners and sockets may be coated with additives to achieve specific performance. For instance, the liners and sockets may be coated with thermochromic additive, i.e., a material which changes its colour due to a change in temperature. Preferably, the coating should be close to the skin or even at a surface directly contacting the skin. The thermochromic coating may be used as a method of sensing temperature, taking advantage of the change of colour due to a change in temperature. It is known that elevated temperatures can produce discomfort, may cause sweating and thus adversely affect the residuum microclimate. Thermochromic compounds can be tailored to transition from one colour to another at a set temperature (the colour change being reversible). By embedding these compounds in the soft lining of the socket or a liner that can show a colour change, it is possible to indicate to a user an elevated stump temperature so that the user can take appropriate action. In addition such thermochromic additives can be added to a fabric applied to a liner.
Another coating that can be applied to the liner and/or socket is piezochromic additive, i.e., a material which changes its colour when pressure is applied. The lining of a socket or a liner can be formulated with piezochromic pigments such that pressure points are visually highlighted. These additives or compounds can be reversible or irreversible and can be tailored to a specific pressure. These additives can also be added to the fabric.
The concepts of coating with piezochromic or thermochromic compounds may be beneficial in daily routines, but also in diagnostics. For instance, in home settings amputees can determine the intensity of the activities they perform and how these activities affect their residuum status. Therefore feedback in the form of the liner/socket colour can be used in the decision making process as to when to rest the residuum. This is particularly important for neuropathic patients, who have impaired sensation. In a clinical setting, prosthetists frequently perform socket diagnostics and seek locations where sockets are either not in contact with residuum, or where excess loading is applied. This is typically performed using sockets made of a transparent material. Having liners or sockets coated with a heat- or load-sensitive additive can greatly assist with identification of those locations.
Another way of suspending the prosthesis may be through the use of metamaterials, including auxetic materials. These are materials that contain structure (at macroscopic or microscopic level) that can be ‘programmed’ to exhibit a bi-stable behaviour: depending on the load applied or temperature, these materials adopt a secondary shape, or perform specific actions. Once example behaviour is where the material has a negative Poisson's ratio, such that it becomes thicker when stretched and thinner when compressed. Other auxetic materials may demonstrate expansion and contraction based on changes in temperature. Such materials can be engineered so that forces applied to them can be transmitted in different direction. For example, the cells can be designed to deform and produce shear when a normal force is applied.
This idea can be applied to a socket or liner construction, with a mesh-type of build where the material is able to react to the elevation of temperatures of the residuum or loading in specific locations (for example due to natural swelling of the residuum). Accordingly, the material may expand and accommodate for the volume fluctuation of the stump, resulting in improved comfort. Alternatively, it can open up pores in the material, to allow ventilation, and get rid of excess sweat.
Another exemplary application of such materials is as follows. It is known that the amputee's residuum shrinks throughout the course of the day. Since the residuum circumference reduces, later in the day the amputees tend to apply more pressure at the distal end of the socket, as the side walls of the socket contribute less to weight bearing. This excess of pressure at the distal end can be transformed by the metamaterials to a programmed area (e.g. side walls, to accommodate for the lost volume and apply additional support to the residuum). This mechanism can be individualised (customised) to the patient. This would require scanning of the residuum shape at various times of the day. Accordingly, the patient can be fitted with a socket/liner that would accommodate for the residuum volume changes that are appropriate to him/her.
It is again to be noted that the sockets presented in
The outer fabric material may also include wearable electronics to provide further indication and diagnostic information relating to the residual limb. For example LEDs, displays, etc. may be incorporated to indicate pressure readings, temperature or activity information. Wearable thermal power harvesting electronics and devices, for example using Peltier and Seebeck effect, may also be incorporated into the liner and or socket interface materials. Piezoelectric devices and or inductive power generation materials and devices may also be used to harvest energy from movements at the socket interface. The piezoelectric devices may also be used to augment feedback. For example, sensory information from the prosthesis related to position or loading can be used to feedback vibration or other actuation means.
Whichever method is used to “capture” the shape of the residuum or limb in question, more than simply surface topography is required.
This is because the socket needs to be:
Therefore whatever method is used to “capture” the residuum or limb in question it is necessary to capture more than simply surface topography. It is also necessary to contain and capture the volumes/areas that are displaced by the stabilisation struts, whilst still allowing muscle groups etc. to function. In the case of flaccid tissue that is not contained or restrained the pressure differential between loaded and unloaded tissues can lead to discomfort and the feeling of increased pressure beneath the stabilisation struts.
Consequently, during the casting or “capture” process it is advised that -especially in the case of flaccid residuums—soft tissues be constrained/loaded with a graded compression distal-proximal (aiding venous return) which will alleviate the pressure differential between areas used for deeper stabilisation and other tissues. Similarly in the finished socket such tissues will require soft tissues to be constrained/loaded with a graded compression distal-proximal whilst still allowing contained tissues/structures to function.
Based on the above considerations, the casting jig should consist of a minimum of 3 stabilising, semi-rigid struts which are sized, positioned and oriented such that they all are equally loaded. The amount the struts indent the residuum during the casting can be controlled at multiple residuum levels along the proximal-distal axis. This can be achieved using, for example, a jig consisting of a series of rings/hoops located one on top of another. Each ring/hoop features at least three threaded inserts. Each insert is attached to one of the struts. During casting, the amputee places the residuum inside the rings/hoops. The struts are subsequently tightened by means of the threaded inserts, so that they make an impression on the amputee's residuum, “shaping” it to the geometry desired for the socket concepts described above. Owing to the fact that there are multiple rings/hoops at multiple levels along the proximal-distal residuum axis, the level of compression/indentation of the struts into the residuum soft tissues can be controlled at multiple points.
The casting apparatus may also consist of instrumentation which measures the stiffness and pressure of the residual limb tissues. This can be achieved, for example, by measuring the pressure and or shear forces at the interface and the displacement of the tissue. Various sensing principles may be used, for example, capacitive based sensor or resistive or a combination of others not limited to these. The data from the tissue analysis captured in the casting rig may also be used to create a solid mechanical model of the residual limb structure. The data then is used for selection of liner and/or socket interface materials to improve comfort and reduce the likelihood of excessive tissue stresses occurring when the socket is worn. The same mechanical model can also be used to optimize the compliance of the socket structures to further enhance comfort.
Once a desired shape is achieved, the residuum shape “capture” is taken.
In addition to the typical methods for “capturing” the residuum shape (e.g., use of plaster of Paris), alternative methods may be possible as well. One way of taking a “capture” of the residuum may be to use textiles with directional stretch vacuumed together. After vacuuming, they will hold shape, thus capturing impression of the residuum as described below. Another method may involve scanning the residuum surface placed in a casting jig using an optical scanner.
as is described below in greater detail.
The function of the powered socket 1A is to adjust the socket 1A to provide one or more of:
The socket 1A includes sensors 21 both within the socket 1A and in a liner 27 to be worn by the amputee. The sensors 21 may sense one or more of:
Data generated by each sensor 21 is passed to a microprocessor forming part of a control unit 23. The data may be passed directly to the microprocessor or by means of an intermediate processor, which may be part of the sensor 21. Instead of the control unit 23 being part of the socket 1A as shown in
The communications modules comprise one or more wired or wireless transmitters or transducers which are mounted within the socket 1A, liner 27 or other part of the lower limb prosthesis system. Wireless communications modules can use any wireless communications protocol, such as Bluetooth®, RF, WiFi® or near field communications. The communications module may be used to communicate between parts of the socket 1A and with external controllers. The external controllers may be part of a dedicated controller device or may be the microprocessor of a mobile device such as a phone 29, tablet or laptop 31, as shown in
The communications modules may further comprise storage means for storing data generated by the sensors 21. The storage means may be internal or may be removable storage means, such as an SD card or the like. Where collated data is stored in the storage means it may not be transmitted externally in real time but may be transmitted only at predetermined intervals. By transmitting data at discrete intervals the socket's 1A power consumption is reduced.
Instead of or in addition to the communications modules including a wireless transmitter or transceiver, they may include a wired transmitter or transceiver. The wired transmitter or receiver may include a port for connecting a cable, such as a USB® or micro USB cable or may include a cable which is hard wired to the socket.
In the embodiment shown in
In particular, each of the wireless transceivers 39, 41, 45, 47 comprises a coil 53 which is connected to a transceiver circuit 55. The transceiver circuits 55 generate a modulated current in the coil 53 which produces magnetic induction in the loop antennas of the coil 53 to produce a field which is picked up by the corresponding coil 53. In addition, the transceiver circuit 55 of each transceiver 41, 45 in the socket 1A generates a field from its coil 53 which generates a current in the corresponding coil 53 of the NFC transceivers 39, 47 in the respective liner 27 and gel pad 49. In this manner power is transferred from the socket 1A to the liner 27 and gel pad 49 and either stored in the liner 27 and gel pad 49 or the liner 27 and gel pad 49 are continuously powered via the transceivers 41, 45, 55. Note that in power transfer operation the transceivers 41, 45 of the socket 1A act as power transmitters (and not as power receivers) and the transceivers of the liner 27 and gel pad 49 act as power receivers (and not as power transmitters).
In another embodiment, the NFC transceivers 55 are substituted with wireless power and data transfer modules, which operate on the following principle. Transceiver circuit 55 generates a modulated current in the coil 53, which produces magnetic induction in the loop antennas of the coil 53 to produce a field which is picked up by the corresponding coil 53. The current generated in the corresponding coil 53 in liner 27 or gel pad 49 is subsequently picked up by transceiver 55 and either stored in the liner 27 and gel pad 49 or the liner 27 and gel pad 49 are continuously powered via the transceivers 41, 45. The communication between transceivers 55 in socket 1A and corresponding transceivers in liner 27 or gel pad 49 is achieved through the modulation of frequency in transceiver 55 in socket 1A or impedance in corresponding transceivers in liner 27 or gel pad 49.
In other embodiments the communications functions of the transceivers may be separated from the power transfer function. In other words, where coils are used for power and data delivery between parts of the sockets 1A, the coil is used only to transfer power from a power transmitter side to a power receiver side. Communication between the socket 1A and liner 27 or gel pad 49 can be achieved by means of other wireless communication involving coil antennas (Bluetooth, RF, NFC, ZigBee, WiFi, etc.) or optical communication (e.g. infrared).
In one embodiment, the liner 27 is a pin-lock liner. The transceiver circuit 55 and coil 53 located in the liner 27 are placed on an umbrella of the liner 27. Once the pin-lock liner is donned, the pin-lock mechanism locates the liner in place and secures the suspension of the residuum and the socket. The locating feature of the pin is used for locating the coils 53 in the liner 27 and socket 1A, so that their concentricity is ensured. In such case, the pin of the pin-lock liner is made of polymer material or the design of the coils 52 accounts for the presence of a metallic pin in their centre, so that the resultant inductance of the transceiver coils 55 in mated condition is suitable for the modulation frequency of the transceiver circuit 55.
In another embodiment, the coil 53 electrically connected to the liner 27 is located in an enclosure outside of the liner 27. Nonetheless, the coil remains electrically connected to the liner 27 by means of wires that extend proximally from the liner. Coil 53 in the socket 1A is placed on the outside, at a proximal location. To allow power transfer between coils 53 electrically connected to the liner 27 and socket 1A, the amputee would need to attach the coil 53 electrically connected to the liner and the coil electrically connected to the socket after donning the socket. The method of attachment of the coils may involve magnetic attraction or a mechanical clip mechanism.
In another embodiment, there are multiple coils inside the liner 27. When the socket is donned, the field generated by the coil 53 located in the socket 1A induces current in one of the coils located in the liner 27. Transceiver circuit 55 located in the liner 27 is able to detect in which coil current is being induced and disconnects other coils, receiving power from the coil which is best placed to receive the power.
In another embodiment, there are multiple coils inside socket 1A, and one coil on the liner side. Similar principles as above apply.
In an alternative embodiment, the socket 1A may include a microprocessor as well as one or more communications modules communicating with an external microprocessor. In such a case the socket 1A may operate automatically by default under the operation of the internal microprocessor whilst the external microprocessor may be used to additionally control the socket 1A or override the operation managed by the external microprocessor. For example, where the internal microprocessor determines to tighten or loosen the socket by operating the actuators, the user may be able to reverse this operation for reasons of comfort or control, by means of an app or the like. Alternatively, the user may be able to override the tightening or loosening action my manually intervening with the socket 1A itself, either by a manual override or by operating a switch on a wall 43 of the socket 1A.
Similarly, the socket 1A may communicate with other prosthetic limbs, such as intelligent ankles, knees, data collection modules, sensors, etc. 33 having their own microprocessors, to provide an integrated limb control system. This includes ankles, knees, data collection modules, sensors, etc. located on the contralateral limb of the same amputee, if an amputee is a bilateral. For example, rather than the sensors 21 being used primarily for sensing the state of the residual limb 20, liner 27 and socket 1A, the sensors 21 may be used to provide gait analysis for controlling other limbs. Furthermore, other prosthetic limb elements, such as intelligent ankles, knees, data collection modules, sensors, etc. 33 may send data to the socket, so that it can perform a specific action according to those signals.
Once it is determined that a tightening or loosening action is required, the socket 1A may use one or more of its actuators to effect a tightening or loosening operation. The actuators may be one or more of:
The actuators may achieve socket shape change through pushing portions of socket in or out. For example, they may push entire support portions (e.g., 85,
This actuation mechanism allows self-adaptation of the socket to the residuum;
Data generated by the sensors 21 can be used to identify one or more of the following conditions and the following actions can be taken to address each condition:
The socket may send data to a cloud storage system 37 for storage and processing to optimise future designs, as well as to improve performance of the existing devices. The data collected by the socket system may include (in raw or processed form):
These transmissions may include continuous streams of data, bursts of data, counts of instances a specific event occurred, timing of those events, etc. In addition to the data transmitted by the socket, during fitting or appointments, prosthetists may also be able to log the interventions they performed, as well as patient's particulars, including the patient's as age, weight, residuum shape, residuum status, etc., but also 3D scans of the stump and socket, X-ray images, MRI outputs etc.
When the stored data is processed, it employs cloud-based computing systems (e.g. IBM Watson® computing scheme), however parts of the computing can be done by the microprocessor on the prosthesis or microprocessor in the telephone/mobile device. A range of different processing techniques may be used, including, but not limited to:
In another embodiment the above-mentioned calculations may be performed in part or in full on any microcontroller located in the prosthesis.
Through identifying dependencies and correlations between different pieces of collected data, the above-mentioned techniques will aim to achieve the following:
The outcomes of the processing may be used:
eventually, benefitting from the data collected from many patients, but prioritising data from the patient wearing the individual preferences of the patient, the socket will become individualised, and will be able to “grow” and adapt to the patient, hence leading to reduced need for appointments with prosthetists, etc.
Factors such as the loads, temperature, humidity, bacteria or other microclimate indicators at the residual limb 20 can be assessed, for the purpose of checking that these factors do not exceed predetermined levels or operate within certain limits. If these factors exceed the predetermined levels there may be a risk of pressure ulcers (PU) or other health problems.
In response to identification of a health risk one or more of the following steps can be taken:
Data from the sensors 21 can be used to assess how comfortable the stump 20 is within the socket 1A by measuring:
In response to an assessment of a lack of comfort, signals can be sent to other prosthetic components, particularly to the socket's actuators as well as to the ankle and knee 33 to optimise comfort. This may be achieved in one or many of the following ways:
In one embodiment, the actuation of the prosthetic socket is performed in the swing phase of gait. This is because the prosthesis is not in contact with the ground and hence the socked is subjected to minimal loading. Therefore, the actuators will not need to ‘fight’ against the loading arising from gait and hence the socket actuation can be achieved at lower energy/power expenditure.
The signals from the sensors, including, load and motions sensors, can also be used to determine amputee activity. This can be used for collection of data on outcome measures as well as justification of the amputee's needs, for reimbursement purposes. Additionally, determination of the activity can be used in other decision-making processes. For example, depending on the activity performed by the amputee, thresholds, permitted ranges of operation, spatial or temporal patterns that are used to perform any functionality described in this patent may vary.
The sensors 21 can be used to assess the intended walking behaviour of the amputee, e.g., if the amputee wants to accelerate, decelerate. This can be detected, for example, through sensing sagittal (antero-posterior) shear from a sensor located at the distal end of the socket or two pressure sensors—one located at the anterior distal and one at posterior distal aspect of the socket. When an amputee intends to decelerate, one or more of the following can indicate this intention:
In contrast, when the amputee wants to accelerate one or more of the following can indicate this intention:
The predetermined thresholds, signal ranges, spatial or temporal patterns that permit identification of amputee intention might vary depending on activity. This may permit, for instance, ability to slow down and speed up walking on slopes (both up and down).
Other sensors may also be utilised to perform detection of the amputee's intention. This includes electro- and mechanomyographic sensors, or stretch sensors, all of which can be used to monitor muscle contractures. Signals from appropriate muscle contractures can be used as control signals, whereby the amputee can send commands to the prosthesis in a similar way the signals are sent to upper limb prostheses, as is known in the art.
In response to identification of the amputee's intention, one or more of the following steps can be taken:
Factors such as the loads, pressure, shear, at the residual limb 20 as well as kinematics, e.g., motion of the residuum in the socket, can be assessed for the purpose of checking that these factors do not exceed predetermined levels, or operate within certain limits. If these factors exceed the predetermined levels or operate within certain limits, this might indicate the timing of the knee release. In response to identification of such event a signal might be sent to a knee to release from stance phase into swing.
Other sensors may also be utilised to perform detection of the amputee's intention. This includes electro- and mechanomyographic sensors, or stretch sensors, all of which could be used to monitor muscle contractures. Signals from appropriate muscle contractures can be used as control signals, whereby the amputee may send commands to the prosthesis in a similar way the signals are sent to upper limb prostheses, as known in the art.
Factors such as motion and/or load may be used to determine that the amputee is seated. In such a case, the socket would open up to allow venous return. In contrary, when the intention to stand up by the amputee is detected, the socket re-adjust to provide additional support. During both sit-to-stand and stand-to-sit, signals can also be sent to other prosthesis components such as ankles and knees, to determine their flexural properties. For example, a foot setting would change to high resistance to plantarflexion, low resistance to dorsiflexion (during both sit-to-stand and stand-to-sit). A knee setting would change to high resistance in flexion, low resistance in extension.
The sensors 21 can be used to monitor and track relative stump 20/socket 1A motion inside the socket 1A (through movement and position sensors), so as to assess if pistoning or angular coupling of the residual limb 20 is taking place within the socket 1A. (Coupling refers to relative movement between the socket and the residuum. There is axial coupling (or pistoning) when the residuum moves along the axis of the socket, but also there exists angular coupling, which refers to angular motion of the residuum and socket.) Among others, this will permit determining risk of blisters/stump health issues, and assess the quality of the socket suspension. Achieving adequate suspension is required to ensure that the amputee is confident in putting the right loading through the prosthesis. Inadequate/asymmetric loading put through the prosthesis may lead to health problems such as back pain.
In response to tracking the stump's 20 motion, one or more of the following steps can be taken:
Stump Position Within the Socket
The sensors 21 can be used to assess if the socket 1A is in the same place as it was when it was fitted, i.e., if it has been subject to any rotation. This can be done by comparing the sensed pressure profile with that recorded when the socket 1A was initially fitted, or at the beginning of the day.
If it has been determined that the stump 20 has moved within the socket 1A one or more of the following steps can be taken:
Detecting a Stumble or Trip
The sensors 21 can be used to detect a risk or presence of a stumble or trip by sensing unexpectedly high pressures at the stump 20, using pressure sensors or vibration sensors, despite that the limb 20 is in swing phase.
In response to a determination of a potential or actual stumble/trip the socket 1A can send data to other prosthetic components, e.g., one or more of the ankle, knee 33 and socket, to trigger stumble mode operation. This information would temporarily firm up the prosthetic knees, ankles and sockets, thereby ensuring improved control over the prosthesis by the amputee as well as reliable means of loadbearing subsequently to the tripping or slipping event.
It is also possible, that other prosthetic components may detect stumble and inform the socket about such a potential event. In such a case, the socket would firm up to ensure the amputee can control the socket.
Additionally, the following actions can be taken:
Additionally, the sensors 21 can be used to assess the level of vacuum in the socket 1A. If an insufficient vacuum is detected, data is sent to the other prosthetic components, in particular to the socket 1A, to improve the seal, or to a vacuum pump to improve the suspension.
Additionally, the following actions can be taken:
The sensors 21 can additionally or alternatively be used to assess the amount of moisture in the socket 1A which may denote a build-up of excess sweat. This can be remedied by activating cooling elements and/or actuating the liner's and socket's smart materials, that open up pores.
Data from the sensors may also be stored internally for debugging purposes. The data may be downloaded by the prosthetist and used as an outcome measure. Furthermore, the data from all the sensors (both live stream and historic) can be accessed remotely either by the prosthetist or by the prosthesis manufacturer/engineers/service centre. The data can be used to remotely alter the properties/settings of the prosthesis (this includes changes of predetermined thresholds or allowed ranges, but also software on the devices), and collection of data for debugging of the prosthesis performance off-line.
Signals from the sensors, such as load (pressure, shear), kinematics (motion sensors), activity/mode etc. can be exchanged between bilateral limbs to identify:
According to the identification of non-symmetrical gait of the patient, the prosthetic components can be altered (for example, damping/resistance of the components can be changed to control velocities, range of motion, loading, etc.) to ensure a more symmetrical gait; and
The sensor signals can be used to provide a sensory feedback to the amputee. More specifically, many amputees (particularly above knee amputees) suffer from the lack of sensation such as:
where and how high the temperature/humidity of the surrounding is, etc..
Having that sensation allows able bodies have a good control over the limb. To provide some form of sensory feedback, signals from sensors such as:
can be converted to stimuli fed back to the amputee. The sensation can be achieved by:
The vibrators/pins/heating elements may be placed in multiple positions in the socket/liner. The intensity, number of, or spatial/temporal pattern of the provided stimuli may correspond to the strength of measured variable. The stimuli may also vary depending on whether the variable crosses a predetermined threshold, is within a predetermined range or when a specific spatial/temporal pattern is detected.
Furthermore, additional stimuli may be used to provide a sensory feedback. Purpose-made feedback devices attaching to the body by means of adhesion or straps can be used in case of patients with tactile impairments at the stump. The devices can contain vibrators/pins/heating elements. Similarly, vibrators/pins/heating devices can be placed on a smart watch. Furthermore, the feedback may be provided through augmented reality, whereby the patient wears goggles or glasses and an image of a prosthetic leg, or another visual aid is superimposed on the view of the amputee and is used to indicate the strength of the measured variable.
Signals from the pressure/shear, contact, sensors may be used to provide feedback to the prosthetist regarding the socket's alignment. In one embodiment, the prosthesis may inform the prosthetist about the magnitude of loading applied to the posterior/anterior or medial/lateral sides of the socket (both during standing, gait or other activities). If that loading exceeds a predetermined threshold, is within a certain range or exhibits certain spatial or temporal pattern, this can trigger an indication to the prosthetists. This can be in form of sound (beeps) or visual (with LEDs of the prosthesis, display on the prosthesis or on a PC/mobile/smart watch app). Alternatively, the signals may also be used as an input to the automated/motorised pyramid alignment interface, which will perform appropriate adjustments to the alignment in automated manner.
For instance, when during standing the socket sensors suggest one or more of the following:
the alignment of the prosthesis can be altered (either by the prosthetist or by automated/motorised pyramid alignment interface) to provide adduction of the socket and/or medial translation of the socket.
When during standing the socket sensors suggest one or more of the following:
the alignment of the prosthesis can be altered (either by the prosthetist or by automated/motorised pyramid alignment interface) to provide abduction of the socket and/or lateral translation of the socket.
When during standing the socket sensors suggest the following:
the alignment of the prosthesis can be altered (either by the prosthetist or by automated/motorised pyramid alignment interface) to provide flexion of the socket and/or posterior translation of the socket.
When during standing the socket sensors suggest the following:
the alignment of the prosthesis can be altered (either by the prosthetist or by automated/motorised pyramid alignment interface) to provide extension of the socket and/or anterior translation of the socket.
When during standing the socket sensors suggest the following:
the alignment of the prosthesis can be altered (either by the prosthetist or by automated/motorised pyramid alignment interface) to provide posterior translation of the socket.
When during standing the socket sensors suggest the following:
the alignment of the prosthesis should be altered (either by the prosthetist or by automated/motorised pyramid alignment interface) to provide anterior translation of the socket.
Further to the display of the loading using the app on the mobile device, in another embodiment, the sensor signals can be visualised using augmented reality technology. In such embodiment, the prosthesis user or a prosthetist films the prosthesis using a camera in a mobile device. The device displays in real-time the filmed image but additionally superimposes signal from the sensors (for example, loading information may be displayed in form of vectors, pressure distribution can be displayed as colour maps overlaid over the socket, traffic light indication of high/medium/low level of loading, using red/amber/green colour scheme etc.).
In order to overlay the vectors/maps/other displays over a filmed image of the prosthesis, the mobile device needs to be able to ‘recognise’ the prosthesis (work out where the prosthesis is). This can be achieved with image processing algorithms allowing for pattern recognition, or using sources of light, such as LEDs (either visible or non-visible spectrum, e.g. infrared) placed on the socket/other prosthetic components. Identification of these LEDs will permit identification of key landmarks on the prosthesis and hence ‘recognition’ of the prosthesis. The LEDs can either produce continuous beam of light or can flash, each with a specific code, which permits identification of the specific landmarks
Similarly, the augmented reality can be displayed using special goggles (e.g. Google Glass®, or similar). Alternatively, 3D holographic projection technology may be employed to produce similar effect, i.e., overlay of certain variables (vectors, pressure maps, traffic light etc.) over the prosthesis. It is envisaged that this will remove the need for laser/optical methods for postural alignment.
Data may be collected by means of one or more of:
The collected data may include one or more of:
The data can be used to monitor the performance of the prosthetic outcome, it may be used to determine amputee activity level, as well as evaluate prosthetic components.
In order to power the sensors 1A, actuators 17P, 17D, control unit 23 and other electrical components in the socket 1A the socket 1A further includes an electrical power storage device, such as a battery, and means for charging the storage device, as described above.
The primary functions of the energy receiver are to receive power from the associated external energy transmitter and to manage the received power (either powering its components only when RF energy available, or charging a battery and feeding components from the battery when RF power is unavailable). Additionally, the energy receiver may incorporate the communications module described above, so that it can communicate with the external energy transceiver.
The energy transceiver is placed inside or outside the socket and its primary functions is to send power to the energy receiver. If the energy receiver also sends data to the energy transceiver then the energy transceiver additionally receives data from the energy receiver and may transmit data/commands to energy receiver.
Data from the sensors 21 in the liner/pad/mat and sent to energy transmitter have to be either:
The socket 1C of
The socket 1C further includes means for cooling/heating the residuum 20 in the form of a thermoelectric element 63 using the Peltier effect. In addition a fan 65 can be incorporated into the socket 1C in communication with channels within the socket 1C and an extraction port 67 through which moisture and sweat can be withdrawn from the socket 1C. In addition, the thermoelectric element 63 can be used to harvest energy from the socket, to charge a battery, which is used as a source of power for the electronic system. Other than the thermoelectric element, the energy can be harvested for example using Stirling engines. Furthermore, energy harvesting may also be achieved with piezoelectric, materials (harvesting of strain, vibration), electromagnetic and electrostatic inertial generators, etc.
Various modifications will be apparent to those in the art and it is desired to include all such modifications as fall within the scope of the accompanying claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1714498.1 | Sep 2017 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2018/052550 | 9/7/2018 | WO | 00 |
