Abstract:
A device for the determination of parameters, particularly for therapeutic compression measures on limbs ( 10 ), comprises an anatomically-modelled limb ( 10 ), to which the compression measures may be applied, with sensors ( 42 ), provided on the limb ( 10 ), for recording said parameter. The surface ( 44 ) of the limb ( 10 ) is at least partially elastically-deformable in at least one direction and at least one simulation device for a muscle ( 22, 24 ) is provided in the limb ( 10 ), which may be controlled to give a merely partial deformation of the surface ( 44 ) of the limb ( 10 ).

Description:
This application is the national stage of PCT/EP2005/007695 filed on Jul. 15, 2005 and also claims Paris Convention priority of DE 10 2004 038 421.5 filed on Jul. 30, 2004. 
     BACKGROUND OF THE INVENTION 
     The invention concerns a device for determining parameters of, in particular, therapeutical compression means on limbs, comprising an anatomically modelled limb to which the compression means can be mounted, wherein the limb has sensors for receiving the parameters to be determined. 
     Compression means of this type may e.g. be so-called “compression socks” or “compression tights”, in general socks or tights having a certain supporting effect, but also corresponding, mostly tubular structures for the arm region, where such measures are used e.g. after breast operations in order to prevent or treat accumulation of liquid in the arms. Such compression means may also be obtained using flat materials, such as e.g. bandages or dressing material, which are applied to the desired limb for compression. These products are mainly knitted fabrics, wherein it is decisive for the success of the therapy, that the pressure on the body surface is sufficient but not too high. The level of compression pressure depends, in particular, on the properties of the material, the processing or production technology and the technique of application. The measurement of parameters, in particular, the applied compression or pressure is advantageous for the production or development of such compression means, but may also be used e.g. to train patients wearing such compression means, or to train the medical and therapeutical staff. The point pressures that result in dependence on the radius of the underlying structure can be theoretically calculated through tensile force relationships of a specific compression material and application of the Laplace formula. This applies to cylindrical and rigid bodies. 
     A plurality of rigid systems of this type have been described in prior art. U.S. Pat. No. 6,334,363 B1 describes e.g. a device for measuring pressure points through therapeutical compression means, wherein a plurality of sensors are provided which are disposed on the surface of the rigid mold that corresponds to a leg. A pressure profile of the compression means can be generated through simultaneous measurement of the pressures at all measuring points and the plurality of measuring points. 
     U.S. Pat. No. 4,137,763 moreover discloses a rigid system which also detects pressure values at a plurality of measuring points. 
     The lower leg or arm of a person, which are the main fields of application of the compression means, are neither cylindrical nor rigid. Depending on the characteristics of the muscles and the mobility of the upper ankle joint or knee, the muscle bellies are shifted during muscle contraction, e.g. during running/walking. This leads to a dynamic system, wherein the perimeters on the lower leg change approximately cyclically with each step. 
     This influences the resulting pressures under a compression means which change in accordance with the step cycle. When the muscle is relaxed, this is called a resting pressure and when it is contracted, a working pressure. The ratio between resting and working pressures of a compression means is the value which is decisive and characteristic for the clinical efficiency of the therapy. 
     EP 1 118 851 A1 discloses e.g. a first approach for improving such devices, which discloses a device for measuring the compression through hosiery, wherein a lower rump is provided from individual tubular elements which are partially formed from shells, wherein the shells can be spread apart in order to model legs having a varying thickness in their longitudinal direction. In this fashion, initial elastic properties of hosiery can be measured. However, the model of anatomical movement is disadvantageously oversimplified due to the individual tubular elements, and simulation of a motion sequence by mechanically opening the tubular segments is also inadequate. 
     GB 2,168,156 A1 also discloses spreading apart, however, for adjusting the measuring body to hosiery to be measured. 
     In another conventional fashion, measurements concerning the dynamic pressure behavior are performed on human beings by disposing pressure sensors onto the skin. The patients were provided with a corresponding compression were instructed to run on a running belt while the pressures were continuously measured. Such measurements are indeed close to practice but can normally only be reproduced or transferred with great difficulty. 
     Due to the fact that there is great variance between the two legs of a single person, from day to day, or even throughout the day, even repeated measurements can approach the precise desired value in vivo to only a limited degree. 
     It is therefore the object of the invention to provide a device of the above-described type which permits reproducible, quasi-continuous measurement of pressures of compression means both in a static and also dynamic fashion. 
     SUMMARY OF THE INVENTION 
     The invention thereby solves the object with a device of the above-described type, wherein the surface of the limb can at least be partially elastically deformed in at least one direction and at least one muscle simulation means is provided in the limb, which can be driven such that the surface of the limb is only partially deformed. 
     In this fashion, the human limb can be realistically modelled with maximum precision. When the limb is a leg, the outer shape of the limb may be modelled like a standard leg (standard sizes of manufacturers of hosiery and also other conventional sizes for producing a leg that maximally resembles a human leg). A model may have, in particular, one or two muscle simulation means, in particular, in the area of the peroneal muscles (musculus triceps surae, musculus gastrocnemius and/or musculus soleus). When an arm is to be modelled, e.g. biceps and triceps may be modelled. The limb may thereby not be completely modelled but e.g. only part of the limb, such as the lower arm or the lower leg. Complete limbs may also be alternatively produced. 
     In order to obtain a particularly good model of a limb, at least two muscle simulation means may be provided, each causing only partial deformation of the limb surface. It may thereby be interesting that the at least two muscles can be driven not simultaneously but at least partially independently and, in particular, in an alternating fashion, such that they imitate muscle contraction or relaxation or simulate motions, such as running/walking. This imitation of muscle relaxation or contraction causes partial deformation of the surface of the limb. 
     At least part of the simulation means may thereby be driven independently and, in particular, alternatingly, and not all muscle simulation means at the same time, wherein driving thereof produces partial deformation of the surface of the limb. 
     The muscle simulation means may thereby comprise a hollow body whose volume and/or shape can be changed, wherein the volume and/or shape change is effected through emptying or filling the hollow body, and partial deformation of the surface of the limb is caused by the different fill levels. The muscle simulation means may thereby, in particular, be filled with air or liquid via hoses. The elasticity of the surface materials thereby permits extension of the thickness of the limbs in the area above the simulated muscles. All relaxation or contraction states of the imitated muscle can be simulated in this fashion. The cover of the hollow body may thereby also be elastic. When further materials are provided between the modelled muscle and the surface of the limb, these may also be elastic. 
     The overall volume and volume flow of the air or liquid may also be adjusted. In this fashion, the speed and the degree of volume displacement during muscle contraction can be adjusted. 
     A system of this type has the following further advantages in addition to the above-mentioned advantages. In addition to quality control in the production of corresponding compression means, a system of this type may also be used for quality control after extensive strain or for aged or otherwise modified materials. Moreover, a corresponding system may be used for developing new compression materials or combinations and for direct comparison of products. Further possible applications are the physiological characterization of compression materials and also quality control in attendance and application, since e.g. nurses and also patients can directly control the success of the application technique. In this fashion, the efficiency of the therapeutical measure can be improved. The surface of the limb may thereby be covered with a synthetic skin. Such synthetic skins are usually used as surfaces for prosthetics. Simulation means for bones and/or soft tissue and/or joints may also be provided. The heel may e.g. be modelled in the foot area using wood and metal elements. A simulation means for the shinbone may also be provided. 
     The simulation means for the soft tissue may be silicone elements, wherein silicones with different elasticity coefficients are used. The overall shape, except for technically required components such as feed lines, bones and muscle elements, may be completely produced from silicone or mixtures or different silicones. It may e.g. be produced by initially using sectional drawings e.g. of a standard leg (standard dimensions from hosiery producers) and converting these sectional drawings to the “50th percentile individual”. The individual sectional drawings are then glued onto rigid foam discs in order to produce a model, are cut out, the disks are fixed on top of each other, and the transitions are smoothed. A negative shape of gypsum is then produced from the rigid foam model and silicone is cast into the negative mold, leaving recesses for the components. The components, such as e.g. hollow bodies for the muscles, rods and further simulation means for bones etc. are then installed. The outer structure, i.e. the synthetic skin is subsequently disposed. The silicone may be silicone of the trademark Elastosil of the company Wacker-Chemie GmbH, which, in its hardened state, may be selected due to its processing properties, viscosity and material properties. It may also be designed in a layered structure from different centrically structured silicone layers. 
     In a preferred example of the invention, the layered structure is formed from silicones of different hardnesses. A silicone of a hardness Shore A of more than 15 (DIN 53505) may e.g. be used inside the device, whereas the layer disposed on the inner layer comprises a silicone of a hardness Shore A of less than 15 (DIN 53505). The simulation means for the muscle(s) is thereby, in particular, surrounded by a silicone of a higher elasticity and mechanical solidity. 
     The sensors may be embedded under the synthetic skin or in skin substitute material. At the respective locations, the skin substitute material may e.g. be punched out to accommodate the sensors, in particular, Piezo pressure sensors. The cables and feed lines or branching off for data transport may be disposed below the artificial skin and be connected to an evaluation unit in such a fashion that the detected data can be used for further processing and/or visualization and/or storage. A suitable number and amount of sensors are thereby mounted to the limb. 
     The limb may moreover comprise one or more regions, in particular, joint regions which are used to simulate movable joints. This is particularly advantageous for hosiery which must be designed, in particular, for the compression properties in the transition area between leg and foot, or between lower leg and upper leg or in the hip area or brachial joints. 
     Finally, means may also be provided in the limb which enlarge the overall circumference of the limb such that the limb can be adjusted to fluctuations of the human structure that occur e.g. during the day, from day to day or between the different seasons and temperatures. 
     Further advantages and features of the invention can be extracted from the accompanying disclosure. The invention is explained in more detail below with reference to a drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  shows a schematic sectional view of a limb of the inventive device in the form of a lower leg; 
         FIG. 2  shows a section through  FIG. 1  along line II-II; 
         FIG. 3  shows a section through  FIG. 1  along line III-III; 
         FIG. 4  shows a section through  FIG. 1  along line IV-IV; 
         FIG. 5  shows an enlarged schematic view of the surface of a limb; and 
         FIG. 6  shows a device in accordance with  FIG. 1  with the associated control and evaluation unit. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows a limb, i.e. a lower leg, having an anatomically modelled shape, wherein the existing data is determined, standardized and then transferred to the present model in order to simulate the limb of the leg of a person. The limb  10  thereby comprises a calf area  12  and a foot area  14 . The connection between the calf area  12  and the foot area  14  of the present model is inflexible, i.e. there are no simulation means for a joint. A supply tube  16  extends through the overall limb  10 , which enters into the limb  10  at the upper edge  18  of the limb  10  and extends to the foot area  14 . The supply tube  16  is used for supply (explained below) of the simulation means for the muscles  22 ,  24  and of the sensors and also to stabilize the limb  10 . The supply tube  16  thereby tapers in the area of the foot  14  where it fulfils merely a holding function in the present limb design, since the present design does not include detection of compression means with respect to working pressure in the area of the foot  14 . The supply tube  16  has a rectangular cross-section in the area of the foot  14 , and a round cross-section in the area of the lower leg  12 . 
     The supply tube  16  is disposed in the area of the front side of the calf area, i.e. close to the shin of a person. 
     The supply tube  16  also serves to hold further components of the device. A wooden element is e.g. mounted in a heel area, as a simulated heel bone  20 , in order to stabilize the foot shape of the device. 
     The limb also has two hollow spaces  22  and  24  whose walls are formed from an air-impermeable elastic material. The hollow spaces are defined by two compressed air cushions of the company Pronal-Leers (FR). The hollow spaces  22  and  24  serve as simulation means for muscles, in the present case, the two main calf muscles. The hollow bodies  22  and  24  may thereby have different volumes. 
     The two muscles  22  and  24  that are simulated by the models are those muscles which are responsible for deformation of the calf area  12  (musculus gastrocnemius and musculus soleus) of a lower leg when a person is walking. The hollow bodies  22  and  24  are connected via holding plates  26  and supply tubes  28  to the supply tube  16 . Air supply and discharge lines are guided in the supply tube  16  and in the supply tubes  28 , which permit filling and emptying of the hollow spaces  22  and  24 . Filling is thereby performed mostly alternatingly between the two hollow spaces to optimally simulate a walking sequence. The feed and discharge lines for air filling may thereby be connected to an external compressor  50  ( FIG. 6 ). A simulation means for a shin  30  is moreover connected to the supply tube  16 , which extends in correspondence with a human shin in the front edge area across the length of the extremity. Holding means  32  are provided for holding the shin model  30 , each connecting the shin model  30  to the supply tube  16 . 
       FIGS. 2 through 5  illustrate the construction of the limb in more detail.  FIG. 2  shows a section along line II-II, wherein the supply tube  16  is disposed eccentrically in the front area of the limb. At a certain separation from the supply tube  16 , the shin imitation  30  is disposed towards the front edge, i.e. the shinbone of the artificial limb  10 . However, the supply tube  28  extends from the supply tube  16  towards the calf, and on to the hollow space  22  that is fixed to the holding plate  26  and coupled there to the supply tube  28 . The holding plate  26  may thereby be coated with a foam material. The supply tube  16  and the supply tube  28 , including a first soft tissue simulation means  34  which is formed from a first silicone (Elastosil M 3500 company Wacker Chemie GmbH (DE)) and extends, at least in the calf area  12 , over the length of the limb  10 , are thereby located between the shin model  30  and the holding plate  26 . The first soft tissue simulation means  34  may thereby be produced from a first silicone material having a first elasticity coefficient. This first silicone material moreover protects and stabilizes the supply tube  16  and the supply tube  28 . The first silicone arrangement  34  moreover supports the simulated shin  30 . 
     The remaining volume of the device is then filled with a further silicone material  36  (Elastosil M 4511 company Wacker Chemie GmbH (DE)) which also serves as simulation means for soft tissue. The second silicone material  36  may thereby be less stable but more elastic and deformable than the first silicone material  34 . The outer surface of the device is then formed by a synthetic skin  38  (Softtouch—covering sock, Otto Bock—Duderstade (DE)) which completely surrounds the device.  FIG. 3  is thereby correspondingly structured. 
     Only a holding plate  40  for the foot is provided in the area of the foot  14 , wherein this is a model for a left foot which can be seen from the different instep heights on the supply tube  16  which consists substantially of a solid material in this case. A silicone material  37  (Elastosil M 4511 company Wacker Chemie GmbH (DE)) is provided in the foot area, which has an even greater stability than the first silicone material  34 . 
       FIG. 5  shows a design of the skin  38 , which is an artificial skin that is usually used for the artificial limb. A piece of the artificial skin  38  is thereby punched out for inserting sensors  42  (pressure sensors company Gisma GmbH-Buggingen (DE)) in the present case a sensor, in particular, a Piezo pressure sensor, such that the surface of the sensor  42  is flush with the surface  44  of the artificial skin  38 . The electric supply and the data lines are guided below the artificial skin  38 , in particular, between the artificial skin  38  and the silicone  36 , and introduced into the supply tube  16  at a suitable location. 
       FIG. 6  shows the complete device arrangement for measuring the compression e.g. of a compression sock that extends to the knee. The compression sock (not shown) is thereby pulled over the limb  10 , like a person wearing this compression sock would put it on. The above-described sensors  42  are thereby distributed over the artificial skin, at least in the overall calf area  12  of the limb  10 . The electric supply and also the line for the data to be recorded thereby extends initially to an A/D converter  60 , and from there, further to a computer-supported evaluation unit  70 . 
     As described above, a compressor  50  is also provided which is connected to the muscle models  22  and  24  via lines  52 . The muscle models  22  and  24  are driven via a compressor control  54  which is responsible for alternatingly filling and emptying the modelled muscles  22  and  24 . The walking sequence is simulated by the amount and the time sequence of filling and emptying. In addition to detecting the static pressure in the resting state of the leg, the dynamic pressure distribution of the therapeutical compression means can also be measured, in the present case the compression sock. It is measured through the values determined by the sensors  42 , which they pass on to the evaluation unit  70  via data lines  62  and the A/D converter. The compressor control  54  is also connected to the evaluation unit  70 . 
     The limb  10  may be suspended on a frame  80  via its supply tube  16 , in order to eliminate any influence on the motion of the calf area  12  due to influences of a support. 
     The determined values for the compression means may then be illustrated, stored and further processed in the evaluation unit  70 .