Abstract:
The invention relates to a prosthesis assembly, comprising an outer stem ( 10 ) provided with a proximal opening ( 11 ), and at the distal end ( 12 ) thereof is provided with a connecting means ( 13 ) for fastening an additional component, and which is formed of a material that is rigid in the longitudinal extension thereof, in which at least one slit ( 14 ) extending at least partially in a longitudinal direction is inserted in order to allow deformation in a radial direction. The prosthesis assembly further comprises an inner stem ( 20 ) made of a flexible material and provided with a proximal opening ( 21 ), at least one tensioning device ( 30 ) that is affixed to the outer stem ( 10 ) and can be accessed by way of a diameter change of the outer stem ( 10 ). At least one electrode ( 40 ) is displaceably fastened to a side of the outer stem ( 10 ) that is facing the inner stem ( 20 ).

Description:
TECHNICAL FIELD 
     The invention relates to a prosthetic appliance comprising an outer socket, which has a proximal opening and, at the distal end thereof, connection means for fastening an additional component, and is formed from a material rigid in the direction of longitudinal extent, wherein at least one slit extending at least partially in the direction of longitudinal extent is introduced into said outer socket in order to enable a deformation in the radial direction, an inner socket, which is formed from a flexible material and has a proximal opening, and at least one tensioning appliance, which is fixed on the outer socket and by means of which a change in diameter of the outer socket is achievable. Such a prosthetic appliance is advantageous, in particular for so-called test prostheses or interim prostheses, which are not individually adapted by molding the amputation stump. 
     BACKGROUND 
     Prostheses have been known for a long time and serve to replace non-existent, e.g. lost limbs. Functional elements, e.g. prosthetic hands or prosthetic feet, are in this case fastened to a dimensionally stable outer socket, which surrounds the amputation stump on all sides and generally has a funnel-shaped embodiment. The outer socket serves to transmit the force from the amputation stump to the functional element. Outer sockets are produced from fiber reinforced plastics, wood or metal and are regularly adapted as precisely as possible to the amputation stump in order, in addition to a high comfort of wear with an ideal support effect, to be able to produce, inter alia, a negative pressure so as to be able to keep the prosthetic socket on the amputation stump. 
     The problem lies in the fact that the volume of an amputation stump varies over time; for example, an amputation stump initially swells up after the amputation or after surgery and then the swelling reduces again. However, a goal of prosthesis care lies in accustoming the patients as quickly as possible to the prosthetic provision. In order to enable, within predetermined boundaries, an adaptation to amputation stumps with changing diameters and lengths, EP 1 411 872 B1 describes a prosthesis which describes a silicone liner with a coupling pin, a prosthetic socket, which has been provided with longitudinal slits and the diameter of which can be changed by means of tensioning elements, and a holder for connecting an artificial limb to the prosthetic socket, in which the longitudinal slits are bypassed. The prosthetic socket has a concentric collar, in which a cylindrical adapter is fastened in a height-adjustable manner. 
     SUMMARY 
     It is an object of the present invention to provide a prosthetic appliance, by means of which it is possible to carry out first care for different patients in a quick and simple manner, even with driven components or functional elements, which are fastened to the outer socket and controlled by myoelectric signals. 
     According to the invention, this object is achieved by a prosthetic appliance with the features of the main claim; advantageous embodiments and developments of the invention are disclosed in the dependent claims, the description and the figures. 
     The prosthetic appliance according to the invention, comprising an outer socket, which has a proximal opening and, at the distal end thereof, connection means for fastening an additional component, and is formed from a material rigid in the direction of longitudinal extent, wherein at least one slit extending at least partially in the direction of longitudinal extent is introduced into said outer socket in order to enable a deformation in the radial direction, an inner socket, which is formed from a flexible, optionally elastic and stretchable material and has a proximal opening, and at least one tensioning appliance, which is fixed on the outer socket and by means of which a change in diameter of the outer socket is achievable, provides for at least one electrode to be displaceably fastened on a side of the outer socket facing the inner socket. 
     Displaceably fastening an electrode to the inner side of the outer socket renders it possible to perform a quick and simple option for testing myoelectric care on a patient, without needing to take a print of the amputation stump in a complicated manner and without an electrode having to be installed in the outer socket with much effort. This renders it possible, even without the provision of an individual prosthetic appliance, to perform test care, and so, for example, suitable prosthetic components such as driven prosthetic hands or prosthetic knee joints can be examined in respect of suitability in principle prior to the final adaptation of the outer socket. This renders it possible to avoid high costs in patient care, since it is already possible to check in advance whether and which driven prosthetic component, which can be fastened to the outer socket, is suitable, how the electrodes are to be arranged and where there can be an advantageous arrangement of the electrodes for controlling the components. 
     A development of the invention provides for at least one area with conductive elements to be provided on the inner socket, which conductive elements conduct myoelectric signals from the inner side of the inner socket to the outer side of the inner socket. By providing at least one area with conductive elements or made of a conductive material, which conducts myoelectric signals from the skin surface of the amputation stump to the outer side of the inner socket, it is possible to cover a relatively large skin surface area suitable for deriving myoelectric signals. It is no longer necessary to position and to affix surface electrodes on the skin surface with much difficulty and then to forward the signals by means of cables to a control appliance; rather, approximate positioning of the area with conductive elements renders it possible to cover a large area of possible myoelectric signal sources without much effort, with said area then being assigned to the electrode arranged on the outer socket. The assignment between the electrode and the area with conductive elements or made of conductive material is then brought about in accordance with the stipulation of the type of signal and the quality of the signal, i.e. to what muscle the signal can be assigned or what signal strength is present. 
     The conductive elements can be embedded in the inner socket or the area of regions can be embodied from a conductive plastic. In principle, it is also possible to form the whole inner socket from a conductive material, in which regions are electrically separated from one another by insulation sections such that myoelectric signals can be recorded along a very large surface. As a result, it is possible to undertake a fast and simple adaptation of myoelectric electrodes since the electrode or electrodes arranged on the outer socket can be positioned in an easily changeable manner. The positioning can be changed even when the prosthetic appliance is still applied, for example if the tensioning appliance is loosened such that the outer socket can be bent open radially to the outside. 
     The inner socket can be affixed to the outer socket; advantageously, the inner socket is affixed permanently to the outer socket such that the prosthetic appliance can be handled as a system of inner socket, outer socket and tensioning appliance together with the optionally likewise permanent but displaceable electrode arranged on the outer socket. The inner socket is advantageously arranged on the outer socket in such a way that, in the case of a restricted area with conductive elements or made of a conductive material, said area is arranged in such a way that it is possible to derive myoelectric signals and that there is a spatial assignment between the electrode and the area. 
     The inner socket advantageously has a closed cross section such that it can easily be placed onto the amputation stump due to the stretchable and elastic material. Therefore, the inner socket is embodied as a variable, adaptable but nevertheless secure inner socket, which forms the interface to the amputation stump. The maximum stretchability of the inner socket is advantageously adapted to the radial flexibility of the outer socket, and so, optionally, provision can be made for pre-manufactured sizes with different diameter gradings. Thus, prosthetic appliances with different sizes can be prepared for different patient types, which sizes cover the whole or almost the whole size range of the patients to be cared for. 
     The inner socket can have an open distal end such that, as a result of the opening, firstly, no pressure is exerted on the distal stump end and, secondly, it is also possible to adapt the length in the proximal direction by displacing the inner socket on the amputation stump. 
     The inner socket is advantageously formed from silicone and can, in regions, consist of a conductive silicone or a mixture of a silicone and a different plastic or conductive material. The outer socket advantageously consists completely of a fiber reinforced plastic. 
     The electrode between the inner socket and the outer socket can be displaceably and/or rotatably mounted in at least one guide which is arranged or formed on the outer socket. It is likewise possible for the electrode to be fastened to the inner side of the outer socket by a special surface embodiment by means of an interlocking element, e.g. a hook-and-loop lock. 
     The electrode is advantageously displaceably mounted in the direction of longitudinal extent and in the circumferential direction of the outer socket, and so the electrode or the electrodes can be positioned relatively freely on the outer socket. 
     Locking appliances can be embodied as tape or belt and set the maximum change in diameter of the outer socket. To this end, the tape or the belt has a closed embodiment or is fastened to the outer socket in such a way that removal or separation of the tape or of the belt is not possible, and so the outer socket and hence also the inner socket cannot be bent open beyond a provided limit. The tensioning appliance also sets the maximum change in diameter during a compression. The tensioning appliance can have a ratchet lock, a lever lock, a rotary clamping lock and/or a hook-and-loop lock; for example, the ratchet lock can be embodied as a rotatable lock which causes a tensioning effect by rotation in one direction and enables loosening by a different actuation. 
     The material of the inner socket can be embodied to be elastic and stretchable or, as an alternative thereto, the inner socket can have a slit in the direction of longitudinal extent. A lateral opening in the inner socket can enable a circumferential adaptation. Overlapping sections, which possibly have a reduced material strength in the region of overlap such that a substantially unchanging material strength can be maintained, likewise meet the requirements placed on a circumferential adaptability. To this end, it is also possible for elastic and stretchable inserts to be introduced into the inner socket. 
     The slit in the outer socket can be partly or completely filled by an elastic material, e.g. an elastomer, in order, for example, to avoid clamping of the inner socket therein without impairing the ability of the outer socket to be opened up. The elastomer can likewise influence the deformation resistance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following text, an exemplary embodiment of the invention will be explained in more detail on the basis of the attached figures. In detail: 
         FIG. 1  shows a rear view of a prosthetic appliance; 
         FIG. 2  shows a front view of a prosthetic appliance; 
         FIG. 3  shows a side view of a prosthetic appliance; 
         FIG. 4  shows a side view of an inner socket; 
         FIG. 5  shows a front view of an inner socket; 
         FIG. 6  shows views of an electrode; 
         FIG. 7  shows a side view of a variant of the inner socket; and 
         FIG. 8  shows a front view of the variant as per  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts a rear view of a prosthetic appliance  1  in the form of a forearm prosthesis. The prosthetic appliance  1  has an outer socket  10  and, arranged therein and fastened thereto, an inner socket  20 . In the depicted exemplary embodiment, the prosthetic appliance  1  is worn on a forearm stump; the forearm stump is not depicted here. Alternatively, applying the prosthetic appliance  1 , the forearm stump is introduced into the inner socket  20  through a proximal opening  21  and the inner socket  20  with the forearm stump is subsequently introduced into a proximal opening  11  of the outer socket  10  and affixed thereto. 
     The outer socket  10  consists of a material that keeps its form, preferably a fiber-reinforced plastic, in which fiber mats, e.g. glass-fiber mats or carbon fiber mats, have been embedded in a plastic matrix. This composite material renders it possible to achieve high strength with low wall thicknesses, while at the same time having a low weight. In the direction of longitudinal extent of the outer socket  10 , very rigid properties are realized by means of this material; compressing or elongating or stretching of the outer socket  10  is not possible along the direction of longitudinal extent, or only to an extremely small extent. The outer socket  10  has a substantially cylindrical set up and, in terms of its contour, substantially corresponds to the contour of a forearm. Connection means  13  for further components, for example a prosthetic hand or the like, are provided at the distal end  12  of the outer shaft  10 . There can be secure coupling between the additional components and the prosthetic appliance  1  by means of the connection means  13 . The connection means  13  enable reversible fastening of the additional component so as to allow an adaptation to the respective usage purpose. 
     Slits  14  have been worked into the outer frame  10 , which slits are substantially arranged in the direction of longitudinal extent of the prosthetic appliance  1 . The slits  14  extend with substantial folding symmetry with respect to a folding axis (not depicted here), which extends along the direction of longitudinal extent of the outer socket  10 ; deviating profiles are possible and envisaged. The slits  14  end before the distal end  12  of the outer socket  10 , and so there is a substantially closed cross section of the outer socket  10  in a tubular form at the distal end  12 . The slits  14  enable mobility of the outer socket  10  in the radial direction. The segments of the outer socket  10  formed by the slits  14 , which segments are interconnected at the distal end  12 , can therefore be displaced inwardly and outwardly in the radial direction, with the outer socket  10  preferably having an elastic embodiment in the radial direction such that, when proceeding from an initial position, a resistive force has to be overcome when bending open or pressing together the segments. 
     Furthermore, guides  15  in the form of slits are provided on the outer socket  10 ; these guides are likewise arranged with an orientation substantially along the direction of longitudinal extent of the outer socket  10  in the depicted exemplary embodiment. The guides  15  can also be embodied as open slits, i.e. not be completely surrounded by the material of the outer socket  10 ; it is likewise possible for the orientation of the guides  15  to extend in the circumferential direction or to describe a curve. 
     The inner socket  20  with the proximal opening  21  can be securely fastened to the outer socket  10 , for example by means of rivets, screws, interlocking elements or the like; as an alternative thereto, a shaping of the outer socket  10  can bring about interlocking latching of the inner socket  20  to the outer socket  10 . The inner socket  20  is preferably formed from silicone; alternative materials can be envisaged. The length of the inner socket  20  depends on the length of the outer socket  10  and on the length of the stump to be cared for. The inner socket  20  usually ends before the distal end  12  of the outer socket  10 . The inner socket  20  advantageously has a closed cross section, but it can also have an open distal end such that length variations of the stump to be cared for can be compensated for and that moreover no pressure is exerted on the possibly still sensitive distal end of the stump. The material of the inner socket  20  is advantageously embodied to be elastic and stretchable; it is likewise possible for there to be a slit in the direction of longitudinal extent of the inner socket  20  such that the inner socket  20 , at least in sections, consists of two plies overlapping one another. Compared to the remaining material of the inner socket  20 , these plies can have a thinner form so that there is no material thickening in the region of the coverage. 
       FIG. 2  depicts the prosthetic appliance  1  in a front view. It is possible to identify both the inner socket  20  with the proximal opening  21  and the outer socket  10  with the slits  14  extending in the direction of longitudinal extent and the guides  15 , which are arranged medially and laterally. Complementing  FIG. 1 ,  FIG. 2  depicts a tensioning appliance  30  in the form of a rotary clamping lock, by means of which it is possible to change the diameter of the outer socket. By rotation in one direction or the other, it is possible to close or open the tensioning appliance  30  by lengthening or shortening the tapes or cables associated with the tensioning appliance  30 . Due to the slits  14  extending in the direction of longitudinal extent of the outer socket  10 , four separate segments result in the proximal region of the outer socket  10 , which segments are oriented in the medial, lateral, dorsal and ventral directions. It is possible to identify in  FIG. 2  that the rotary clamping lock  30  is arranged on the side of the outer socket  10  arranged ventrally, i.e. on the segment facing the bend of the elbow. 
     The inner socket  20  can consist of a plastic or silicone which, in different regions, has different Shore-hardness values such that the stump to be held therein is embedded ideally. 
     By means of the rotary clamping lock  30  it is possible to bring about a change in the circumference of the tensioning means such that a force acting in the radial direction is applied to the outer socket  10 , the inner socket  20  and, thereby, onto the stump. This renders it possible to set the prosthetic appliance  1  individually to the stump of the user of the prosthetic appliance  1  by means of the tensioning appliance  30  and thus adapt it to said user. This appliance renders it possible to store a pre-manufactured outer socket  10  or a plurality of outer sockets in standard sizes and then adapt this individually to the patient, and so the expensive and complicated individual adaptation by taking a plaster cast and manufacturing a prosthetic socket with fiber-reinforced composite materials is not necessary. Such a prosthetic appliance can preferably be used as a so-called test prosthesis such that the suitability in principle of such a prosthetic appliance for a patient can be examined without great financial outlay. Such a test prosthetic appliance is particularly advantageous for patients who, for the first time, are equipped with a driven prosthetic appliance controlled by myoelectric signals. 
       FIG. 3  depicts a side view of the prosthetic appliance  1  having the outer socket  10 , the inner socket  20  and the tensioning appliance  30 .  FIG. 3  shows that an electrode  40  is guided in a displaceable manner in the guides  15  of the segments oriented medially and laterally. A bolt or pin is fastened to the electrode  40  and protrudes through the guide  15  embodied as a slit to the outer side of the outer socket  10  such that the electrode  40  is arranged between the inner side of the outer socket  10  and the outer side of the inner socket  20 . The electrode  40  can be moved along the guide  15 , presently substantially along the direction of longitudinal extent of the outer socket  10 . The electrode  40  can be rotatably mounted within the guide  15  such that the electrode  40  can be arranged ideally on the patient. By fastening appliances, e.g. threaded screws, wedges, clips or the like, it is possible to affix the electrode  40  on the outer socket  10  in the position considered to be expedient. 
     It is furthermore possible to identify in  FIG. 3  that the tensioning means  30  is substantially guided circumferentially around the outer socket  40 . Thus, two belts of the rotary clamping lock  30  can be guided around the outer socket in the circumferential direction and fastened to the opposite segment, in this case the dorsal end segment. By rotation in the clockwise direction, the tension on the tensioning means is increased, and so there can be a change in diameter of the outer socket  10  by displacing the segments separated by the slits  14 . If the rotary clamping lock  30  is actuated in the counterclockwise direction, the outer socket  10  is sprung back into the initial position. Locking appliances can be provided to avoid excessive widening of the outer socket  10  and of the inner socket  20 . To this end, the tensioning appliance  30  can be equipped with an end stop such that when a maximum widening is reached, a locking effect occurs; alternatively, a separate locking appliance is possible. 
       FIG. 4  shows the inner socket  20  in a side view. The inner socket  20  has an area  22  on the medial side of the inner socket  20 , in which a multiplicity of 15 conductive elements  23  are arranged. In the depicted exemplary embodiment, the conductive elements  23  are embodied as parallel, substantially rectangular elements  23 , by means of which myoelectric signals from the skin surface can be conducted from an inner side of  20  the inner socket  20  to an outer side  25  of the inner socket  20 . Provision is likewise made for fastening elements  27  on the inner socket, by means of which fastening elements the inner socket  20  can be fastened to the outer socket  10 . 
       FIG. 5  shows a front view of the inner socket  20  with the proximal opening  21  and the distal opening  26 . It can be gathered from  FIG. 5  that the conductive elements  23  also protrude through the surface of an inner side  24  of the inner socket  20  such that myoelectric signals from the stump (not depicted here) can be conducted from the inner side  24  of the inner socket  20  to the outer side  25  of the inner socket  20  through the conductive elements  23 . It can likewise be gathered from  FIG. 5  that two areas  22  with conductive elements  23  are provided on the inner socket  20 , namely arranged medially and laterally. In principle, it is also possible for more than two areas  22  with conductive elements  23  to be arranged on the inner socket  20 . 
       FIG. 6  depicts two views of an electrode  40 . The upper illustration shows the outer side of the electrode  40 ; the lower illustration shows the inner side of the electrode  40 . In the installed state, as shown in  FIG. 3 , the inner side of the electrode  40  is assigned to the area  22  with the conductive elements  23 . It is possible to identify sensors or pick-ups on the inner side of the electrode  40 ; these are embodied in a manner corresponding to the conductive elements  23 . By displacing the assembled electrode  40  on the outer socket  10  within the guide  15 , it is possible to set a preliminary ideal position of the electrode  40  for obtaining one or more myoelectric signals. To this end, it is not necessary to set surface electrodes on the skin of the patient and already establish an assignment between the position of the electrode and a region on the skin surface. Rather, it is possible to cover a large region of possible derivation points for myoelectric signals by the multiplicity of conductive elements  23 , which region is set by the position of the electrode  40  on the outer side  25  of the inner socket  20  in the area  22  of the conductive elements  23 , wherein the position of the electrode  40  within the area  22  can be freely selected within the region permitted by the guide  15 . 
       FIGS. 7 and 8  depict a variant of the invention, in which round conductive elements  23  are arranged in the areas  22  on the inner socket  20  instead of the polygonal conductive elements. The electric conductive elements  23  can be inserted retrospectively into the inner socket  20 ; it is likewise possible for the inner socket  20  to consist of a conductive material which is electrically separated by insulation material. It is likewise possible for conductive silicone or conductive plastic to be arranged in electrically decoupled or insulated regions as conductive elements  23  in the areas  22  so as to form the conductive elements  23  at different positions in the area  22 .