WO2005044105A1

WO2005044105A1 - Portable pedopowergraph

Info

Publication number: WO2005044105A1
Application number: PCT/IN2004/000339
Authority: WO
Inventors: Vengesana Balakrishnaraja Narayana Murthy; Rajavelu Parivalavan; Keelanje Mothiram Patil
Original assignee: Sundaram Medical Foundation; Indian Institute Of Technology
Priority date: 2003-11-06
Filing date: 2004-11-02
Publication date: 2005-05-19

Abstract

It consists of a glass plate (1) mounted on wooden box and surrounded on longitudinal sides by light fixtures (3) that illuminate it from its longitudinal thickness. Thin sheet (2) covers the glass plate. When a person stand on the thin sheet (2), foot pressure images are formed at the contact surface of thin sheet and the glass plate by the scattering of light. Foot images have distribution of light intensities along the length and breadth of both feet. Distribution depend on foot sole hardness and pressure exerted by feet. Images are reflected through the mirror (4) kept at an appropriate angle to the glass plate (1) and captured by still digital camera (5). Images recorded as BMP files are analysed to obtain the high frequency power and the total power. Power ratio (PR) a new parameter is used in this device for screening of diabetic feet at risk.

Description

PORTABLE PEDOPOWERGRAPH

Field of Invention This invention relates to device which detect diabetic foot at risk. More particularly this invention relates to an unique device namely Portable Pedopowergraph, intended to detect diabetic foot at risk, forewarn that the foot will ulcerate if appropriate remedies are not taken. Hence the invention as its salient feature focus on diagnosis in forewarning the person to take adequate measure to prevent occurrence of foot sole ulcers.

Prior Art

Diabetes mellitus is increasing globally. Foot ulceration is a common sequel to diabetes mellitus. Foot ulceration in the diabetic patient is the most common single precursor to amputation having been identified in 85 % of lower extremity amputations. Foot ulcers occur in feet that are either insensate or ischemic or both and subjected to high foot pressures. Early detection of loss of sensation is an important part of managing "the foot at risk of plantar ulceration". Therefore it becomes important to measure the foot pressure and relate it to the level of foot sole sensory loss to detect early the foot at risk of plantar ulceration.

Many investigators Chodera et al (1957,Fu-Czechoslovakian Academy of Sciences,Prague,Vol.1-3,p.427), Betts et al 980, Med.Biol. Engg. Comput, Vol.18,674-684), Franks et al (1983.Med.Biol.Engg. Comput., Vol.21, 566-572), Boulton et al (1983, Diabetic Care, Vol. 6,26-33), Veves et al (1989, Diabetic Care, Vol.12,653-655), Veves et al.,(1992,Diabetic Care, Vol.15,905-907) have used the optical pedo barograph to measure foot pressures. These workers studied just 1 foot because the pedobarograph used could accommodate only 1 foot at a time. In patients with neuropathy (as in diabetes), both feet can and are often affected, it is therefore necessary to study both feet simultaneously

Optical pedobarograph uses the property of scattering of light at the interface of plastic and glass interface for foot image formation. The foot image is captured by a video camera. The pedobarograph had load cells at the bottom of the pedobarographic box. The load values from these are also recorded simultaneously along with light intensities in the foot image. The foot image data is calibrated using load data and compared to give discrete foot pressure (or peak pressure values) in N/cm2 at only one point of each of the 10 foot sole areas (Fig.1).

There are other commercially available systems like EMED, FSCAN and MUSGRAVE foot print systems. The most common variables of interest measurable currently include peak and average pressure, force, and area. Peak pressure plots represent the highest pressure value recorded by each sensor over the entire stance phase. The software provides values for pressure and a user-specified color scheme to graphically display the pressures acting on the plantar surface of the foot. EMED foot print system measures foot pressures using matrix of capacitive transducers embedded in metal platform. A capacitance transducer consists of 2 plates made of a conducting material separated by a non-conducting or insulating layer termed a "dielectric." The transducer stores an electrical charge, and the 2 plates are compressed when force is applied, causing the distance between the plates to decrease. As the distance between the plates decreases, the capacitance increases, and the resulting change in voltage is measured . Both the FSCAN and MUSGRAVE foot print systems use a matrix of force sensing resistors embedded in metal platform for measuring foot pressures. Force-sensing resistors (FSR) are very thin layered device with metal patterns printed on 2 Mylar sheets with a conductive polymer layer embedded between the 2 sheets. The conductive layer reduces resistance to the flow of electrons as the pressure between the Mylar layers increases. This pressure between the Mylar layers causes the resistance to decrease. The output of devices using this type of sensor technology can be either force or pressure. The force measured, however, is vertical force.

A video pedobarograph system (US 5722287) provides real time display of qualitative relative pressure measurements. This system consists of force sensor matrix structure fixed securely on the planar surface of the rigid'support platform and video pedobarographic electronics. The force sensors generate dynamic relative pressure signals and are positioned within a force sensor matrix structure. The video pedobarograph electronics includes a video sync stripper and control logic. The video stripper strips a video sync signal from a composite video signal received by the video pedobarograph electronics. The control logic maps the dynamic relative pressure signals to the composite video in response to the video sync signal to generate a mapped composite video signal providing a qualitative display of the dynamic relative pressure signals within a predetermined portion of an overall video image generated from the mapped composite video signal.

Since video pedobarograph system is based on discrete force transducer matrix, it suffers from inaccuracies of the order of 33 % in measuring the relative pressures (as per the analysis of Lord, M., 1997, Med.Eng.Phys. vol.19, 140- 144).

All these conventional systems (Fig. 2) have matrix of sensors embedded in metal platform (part No.1), a computer for data acquisition storage and retrieval for analysis of foot pressure (part No. 2) and a monitor ( Part 3) for display of data on foot pressure. The person stands on the platform (part No. 1). This platform can accommodate only one foot at a time. The clinical application is based only on peak foot pressure in each of the ten areas indicated in Figure 1.

The limitation of the Prior Art devices and the need for a new device are summarised as follows

Studies by Boulton et al (1983, Diabetic Care, Vol.6,26-33), Veves et al (1989, Diabetic Care, Vol.12, 653-655), Veves et al, (1992, Diabetic Care, Vol.15, 905-907), Patil et al(1990,Med. Biol. Engg. Comput, Vol.28,416-422, Patil et al, (1996, Innov. Tech. Biol. Med, Vol.17, 401-408) and Prabhu et al (2001, Math. Model. Sci. Comput, Vol.13,79-89) as well other studies based on commercially available platforms have defined peak foot pressures and loss of protective sensation as the cause of foot sole ulcers in diabetic neuropathy.

1. These devices did not define the ulcer risk threshold completely; indeed, diabetic patients may develop ulcers at pressures that are "normal".

2. The loss of protective sensation of foot sole soft tissue was not defined in the former studies (Patil et al 1999, Front.Med.Biol.Engg.Vol.9,49-62) .

3. The mean peak foot pressures in some of the healthy participants (36%) were also abnormally high (Veves et al 1992, Diabetic Care.Vol.15,905-907).

4. Mean peak foot pressure was unable to discriminate between "normals" and diabetics with or without neuropathy.

5. Similarly, the mean peak foot pressure parameters, normalized peak pressure (NPP) and pressure contact ratios (PCR), normalized with respect to weight and walking velocity of the test participant, were not able to discriminate between non-ulcerated and ulcerated feet in neuropathy (Patil et al 1997, Proc.19^,π. Int. Conf. IEEE/EMBS,Chicago,USA,1826-1828, Patil et al,1999,Front.Med.Biol.Engg.Vol.9,49-62).

6. The commercially available devices like EMED and FSCAN, and the recent apparatus, Video pedobarograph (US 5722287) etc. use only peak foot pressure for relating and detecting foot at risk in diabetes. Hence these also fail to detect foot at risk in all cases of diabetic subjects (as described in the earlier section). The video pedobarograph does not provide information about the absolute and quantitative value of pressures. Since this provides only qualitative and relative value of pressures, its use is limited, and it cannot be used in measuring accurate and absolute values of foot pressures to detect foot at risk of foot sole ulcers in diabetes.

7. These methods used only discrete number of transducers on the foot platform. Therefore these systems have an error of 33% in their measurements

(as per the work of Lord, M., 1997, Med. Eng. Phys. Vol.19, 140-144).

8. These devices are very costly (about 10 times costlier than the present invention).

The new invention "Portable Pedopowergraph" has many improvements as compared to earlier used devices. 1. the new device is small and portable, 2. It uses superior lighting system in the light source for superior, sharper quality foot images. 3. It uses digital camera (state of art of present technology and much cheaper than video camera and digitizer) for recording (capturing) foot images. 4. Digital camera^" gives very good quality BMP foot images for image processing and in the calculation of the foot power parameter PR. 5. The new device uses PR (the power ratio calculated based on actual foot pressure distribution on the foot sole) and thus overcomes the limitations of the earlier devices which used only peak foot pressure parameter.

5 The limitations of using only peak foot pressures had made us invent the new parameter Power Ratio (PR) which is based on the actual foot pressure distribution as seen from distributions of foot image on the foot sole during walking or standing.

^ Q Saiient features of the Power Ratio arid its uniqueness in the context of the present invention is as follows

The new parameter - power ratio, PR is the ratio of high frequency power to total power in the foot image. The parameter peak foot pressure used

15 by other investigators depends upon only one peak value of pressure in each part of foot sole. This peak pressure parameter used by other investigators does not take into account the sudden changes in the foot pressure taking place on the sole of the foot and possibly responsible for plantar ulcers. Whereas the new parameter - Power Ratio, PR depends upon the actual foot pressure 0 (image intensity variations) distributions and therefore considers the peak pressure as well as its sudden changes. Therefore PR is more realistic and unique and helps in early detection of foot at risk of plantar ulcers by discriminating the different levels(Viz. 4.5 gm diminished light touch, 7gm diminished protective sensation and 10gm which is the loss of protective 5 sensation) of foot sole sensory loss in the diabetic foot.

Since new parameter PR, is superior to discriminate between normal and diabetic feet in all 3 levels of sensation loss and also is able to detect diabetic feet at risk of plantar ulcers, it is preferred. 0 It is also observed by our experiments that analysis of standing foot pressure images for PR alone is sufficient as compared to dynamic foot pressure measurements. The instrument available in the art are large to capture the walking foot pressures, whereas the present invention can be portable and small because there is no need to capture walking foot pressures. Therefore, portable pedopowergragh can be used for foot image formation.

In the new portable system invented, the CFL lamp is used in the light source and it gives a better and sharper image than used in our previous studies. Again the video digitizer used in the previous studies is dispensed with, since digital camera directly gives better BMP images needed for PR calculation. Therefore, the new system becomes much cheaper than the previously used systems and also becomes portable since it |s sufficient to use only standing foot images.

It is to be noted that the prior art description gives in detail information of the technology, method, process and system known in the art. It explains the deficiency in the related art and the object of the invention being to overcome or surmount the problem associated with the prior art This forms the essential feature and the object of the invention. .

SUMMARY OF INVENTION

The inventors have made great effort to provide a device which meet the requirement of the industry and to overcome the problem associated in the prior art.

To achieve the above object according to first aspect and feature of the present invention there is provided a device to improve, efficiency. According to second aspect and feature of the invention in addition to the first feature the invention comprises a device, which is unique, rugged, efficient, and economical. At the outset of the description which follows, it is to be understood that ensuing description only illustrate a particular form of this invention. However, such particular form is only an exemplary embodiment without intending to imply any limitation on the scope of this invention. Accordingly, the description is to be understood as an exemplary embodiment and reading of the invention is not intended to be taken restrictively.

The above and other objects features and disadvantages will be clear from the following description of preferred embodiment taken in conjunction with accompanying drawings.

The .foregoing description is outlined rather broadly preferred and alternative feature of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for manufacturing by way of and modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should realize such equivalent conception do not depart from the spirit and scope of the invention in its broadest form.

Statement of invention:

The present invention pertains to Portable Pedopowergraph, comprising a glass plate mounted on a box and surrounded on the longitudinal sides by light sources, the light sources illuminating the glass plate from its longitudinal thickness, the glass plate being covered by a thin white plastic sheet, when a person stands on the plastic sheet, foot pressure images of both feet being formed simultaneously at the contact surface of plastic sheet and the glass plate by the phenomenon of light scattering, foot images having distribution of light intensities along the length and breadth of both the feet, the distribution depending upon the foot sole hardness and pressure exerted by the diabetic or any subject, foot images being reflected through the mirror kept at an appropriate angle to the glass plate and captured by a still digital camera recording the image and in the form of BMP files and analyzing by a computer to obtain the high frequency power and the total power in the actual foot image distributions to obtain PR as defined using an image signal processing software

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are intended to provide further understanding of invention and is incorporated in and constitute a part of the invention. The drawings illustrate an embodiment of invention and together with the description illustrate principle of invention.

The drawings should not be taken as implying any necessary limitation on the essential scope of invention.

The drawings are given by way of non-limitative example to explain the nature of the invention.

For a more complete understanding of the instant invention reference is now made to the following description taken in conjunction with accompanying drawings. The various features of novelty which characterise the invention are pointed out^' specifically in the claims which forms part of the description. For a better understanding of the invention, its operating advantage, specific objects obtained by its use, reference should be made to the drawings and descriptive matter in which these are illustrated and described as preferred embodiments of invention.

Referring now to drawings, where like numerals designate identical or corresponding parts throughout the referred views.

Figure 1 of the drawings shows in elevation foot sole areas divided into 10 parts according to accepted convention,

Figure 2 of the drawings shows the block diagram of discrete Sensor Based Foot Pressure Measuring System according to existing measurement techniques,

Figure 3 of the drawings shows in elevation, the Portable Pedopowergraph according to the present invention.

Figure 4 of the drawings shows foot sole areas divided into 17 parts for image processing and to find PR for each area according to the present invention. Figure 5 of the drawings shows foot sole areas divided into 17 parts for image processing software, according to the present invention.

Figure 6 of the drawings shows the flow chart for analysis of foot pressμre images for calculation of Power Ratio, according to the present invention. Figure 7 of the drawings shows the PR display of Pedopowergraph, according to the present invention.^' The portable pedopowergraph consists of a glass plate mounted on a box and surrounded on the longitudinal sides by light sources. The light sources illuminate the glass plate from its longitudinal thickness. The glass plate is covered by a thin white plastic sheet. When a person stands on the plastic sheet, foot pressure images are formed at the contact surface of plastic sheet and the glass plate by the phenomenon of light scattering. This foot images have distribution of light intensities along the length and breadth of both the feet, the distribution depends upon the foot sole hardness and pressure exerted by the diabetic subject. The foot images are reflected through the mirror kept at an appropriate angle to the glass plate and captured by a still digital camera. The foot images recorded in the form of BMP files are analysed to obtain the high frequency power and the total power in the foot image distributions using image signal processing.

The ratio of high frequency power to the total power known as power ratio (PR) is calculated for each area of foot sole to relate them to the foot sole sensory loss and thereby used to help to detect foot sole at risk of ulcers. The PR values on the foot sole are also displayed in pseudo colour form so as to help the doctor to detect quickly the foot at risk of ulcers. Thus the new portable indigenous device, which uses unique foot power parameter and with no maintenance cost, can be used for mass screening of diabetic subjects.

Figure 3 shows the portable Pedopowergraph according to the present invention which is the measuring device for calculation of power ratio, a new parameter of standing foot pressure, obtained by analysis of foot images formed on the device. The device has the following features.

1. a glass plate of appropriate size,

2. a thin white plastic sheet

3. a pair of light fixtures on the entire length of the glass plate containing CFL lamp of adequate watts on each side,

4. a mirror kept below the glass plate at appropriate angle to the horizontal to reflect the foot image formed on the glass plate,

5. a digital (still) camera to capture the standing foot image reflected 6. from the mirror and an appropriate computer system to process the image,

7. a wooden box which supports glass plate, light fixtures and the mirror.

It is a salient feature of the invention that it uses glass plate over which a thin plastic sheet is covered and the foot pressure image is formed by scattering of light at the interface of glass plate and plastic sheet and the foot pressure is measured by the variation of foot image intensities. Foot pressure displayed is continuous and not discrete. Resolution of foot pressure is much better. Minimum area for pressure measurement depends on the pixel area and is 0.035 square centimeters.

The parameter, used to assess diabetic or any other foot problem is the new superior parameter PR, the Power Ratio which is calculated based on analysis of actual foot pressure distribution on the foot sole and this is able to discriminate between different levels of foot sole neuropathy and helps in the early detection of foot at risk of foot sole ulcers. The device measures the new parameter PR related to the foot pressure on both the foot simultaneously and helps in right diagnosis. Another salient feature of the invention is that it has no moving parts and eliminates the need for finite sensing elements such as capacitive sensors or force sensing resistors.

The manner in which the invention is performed is described in the following description. The glass plate is illuminated from sides by CFL lamps such that the light passes through the thickness of the glass plate. When a person or diabetic subject stands over the thin white plastic sheet (kept over the glass plate) there is scattering of light at the contact points (at the micro level) between the plastic sheet and glass plate. The foot image is formed by well known principle in physics, namely, the scattering of light at the glass-plastic interface. Higher the pressure exerted by the foot, more number of points (at the micro level) from under the plastic sheet come in contact with glass plate, and the intensity of light in the foot image increases.

The foot images of both the feet are captured by using the still digital camera. The digital camera directly gives the foot images in the form of BMP (bit map) images.

The BMP images are analysed using software as explained below

The BMP images of the foot have varying intensities of light distributions over the length and breadth of the foot image. These images are divided into 17 divisions (for each foot sole) as shown in Fig.4. Each of these irnage distributions in the 17 foot sole areas contains high and^' low frequency variations of light intensities. These distribution of image are analysed using Fast Fourier Transforms and the power spectrum in these images are obtained by squaring the Fourier spectrum (Gonzalez et al 1987, Digital Image Processing, Second Ed.,Addison-Wesley,USA) in the respective foot sole areas. M-1 N-1 Total Power, TP = Σ Σ [ F(u,v)]² (volt ²) u=0 v=0 The high frequency power (HFP) in the power spectrum is calculated and this is divided by the total power in the image to get the Power Ratio.

Power Ratio, PR = (HFP/TP) This process is repeated in each of the 17 areas of each foot.

The calculated Power Ratios (PR) over both the foot in 17 areas (for each foot) are displayed in the form of colour display (Fig 7). The different colour codes of display of PR vary from blue, green, yellow, orange and red in the increasing order of its value, the lowest one, blue in colour indicating normal, green indicating very early

stage of diabetic neuropathy, yellow indicating early stage of diabetic neuropathy, orange and red indicating the intermediate and advanced level of diabetic neuropathy. Thus, the colours give the doctor, quickly the state of the foot sole, in diabetic neuropathy for early preventive action. Flow Chart or Algorithm of the Process

The details of the flow chart or algorithm of the software are given in the enclosure ( Fig 6).

The Salient features of the software are as follows 1. Software uses the filtered greyscale BMP foot image. 2. It reads left foot bmp or right foot bmp from the folder into the control point selection tool for aligning the image in the required orientation. 3. It aligns the read image of the foot in the desired orientation. 4. Crops the image of each foot into 17 anatomical regions and saves 17 images. 5. It takes each of the 17 regions and finds the Fourier spectrum of the spatial variation of intensity distribution in the required foot area. 6. The Power spectrum for the same foot area is calculated from Fourier spectrum to calculate high frequency (HFP) power and total power (TP) 7. The power ratio PR is calculated as the ratio of HFP to the total power TP. It is multiplied by 100 to convert the fraction into a whole number. 8. It assigns colour code to the foot images depending on the PR value of the foot region. 9. Saves the colour images, colour code varies from shades of blue (PR<20), green (PR 20-30), yellow (PR 30-40), orange (PR 40-50) and red (PR>50). 10. Displays the coloured foot images of left and right feet together. 11. Displays the PR value of each region. 12. Displays the colour code bar for reference. Further details regarding various Salient features of the software intended to be used along with the device is as follows

1. Software is developed using Matlab which is a high performance language for technical computing. It also has a number of tool boxes which are a comprehensive collection of Matlab functions that extend the Matlab environment to solve particular problems. The various Matlab functions and image processing tool box has been used in making this software. 2. First the control point selection window is opened in Matlab which displays the foot image required to be processed or unaligned image and a reference image. The reference image is in the desired orientation required. 3. Two pairs of control points each are selected on the unaligned image and the corresponding points selected on the reference image [ points being are on the area 9 (second toe) and other the tip of heel ]. 4. The unaligned image is then transformed and aligned in the direction of reference image and this image is saved. 5. The transformed foot image is then converted into binary format for further cropping into 17 anatomical regions of the foot sole using properties of binary image such as bounding box, label number, area of region enclosed etc. 6. While cropping the binary image the corresponding regions or areas of the transformed grayscale image is also cropped and saved. 7. The images (17 anatomical regions of the foot sole ) saved above are then used for calculation of Power Ratio (PR) of the foot sole region. The high frequency and low frequency power of the image are calculated by using Fourier transforms and associated functions in Matlab to calculate PR . 8. Based on the PR value of the region the binary image of the corresponding region is assigned a particular colour code and the coloured image is also saved. 9. After PR of all 17 regions is found and colour image saved, the different colour images (which are basically matrices) are then joined together to form the original foot image in the coloured format. 10. The patient data, date and. PR values in figures are also displayed by means of graphic user interfacing.

Block Diagram Indicating Position of Software in Relation to the Portable Pedopowergraph

The details of the block diagram indicating the position of the software in relation to the Portable Pedopowergraph is shown in Fig. 5.

Calculation of the parameter PR

First the BMP file of the foot image is converted to grey scale and an appropriate filter is used to remove the background noises etc. The filtered image of the foot is then divided into 17 parts (Fig.4). The distribution of image intensity variations in each part of the foot sole are subjected to Fast Fourier Transform (FFT) to obtain the spatial frequency variations (Fourier spectrum) of the image intensities. The power spectrum in the spatial frequency variations is obtained by squaring the Fourier spectrum (Gonzalez et al 1987). Next, the high frequency power (HFP) and the total power (TP) in the power spectrum are calculated. The ratio of high frequency power to the total power gives the parameter PR. Similary PR are calculated for all the 17 parts of each foot.

Then the values of PR on all parts of both the feet are printed and displayed in the form of colour display. Range of PR The PR varies from 5 to 60 for standing foot. The range of PR for normal is from 10 to 20. In the very early stage of diabetic neuropathy PR varies between 20 and 30. In the early stage of diabetic neuropathy PR varies between 30 and 40. In the intermediate stage of diabetic neuropathy PR varies from 40 to 50. In the advanced stage of diabetic neuropathy PR is > 50.

4. Comparison of existing devices and present Invention

The invention has been explained in relation to specific embodiment. It is inferred that the foregoing description is only illustrative of the present invention and it is not intended that the invention be limited or restrictive thereto. Many other specific embodiments of the present invention will be apparent to one skilled in the art from the foregoing disclosure. All substitution, alterations and modification of the present invention which come within the scope of the following claims are to which the present invention is readily susceptible without departing from the spirit of the invention. The scope of the invention should therefore be determined not with reference to the above description but should be determined with reference to appended claims along with full scope of equivalents to which such claims are entitled.

Claims

1 Portable Pedopowergraph comprising a glass plate mounted on a box and surrounded on the longitudinal sides by light sources, the light sources illuminating the glass plate from its longitudinal thickness, the glass plate being covered by a thin white plastic sheet, when a person stands on the plastic sheet, foot pressure images of both feet being formed simultaneously at the contact surface of plastic sheet and the glass plate by the phenomenon of light scattering, foot images having distribution of light intensities along the length and breadth of both the feet, the distribution depending upon the foot sole hardness and pressure exerted by the diabetic or any subject, foot images being reflected through the mirror kept at an appropriate angle to the glass plate and captured by a still digital camera recording the image and in the form of BMP files and analyzing by a computer to obtain the high frequency power and the total power in the actual foot image distributions to obtain PR using an image signal! processing software

2. Portable Pedopowergraph as claimed in claim 1 wherein the device has a glass plate of appropriate size, a thin white plastic sheet, a pair of light fixtures on the entire length of the glass plate containing CFL lamp of adequate watts on each side, a mirror kept below the glass plate at appropriate angle to the horizontal to reflect the foot image formed on the glass plate, a digital (still) camera to capture the standing foot image reflected from the mirror and an appropriate computer system to process the image and a box which supports glass plate, light fixtures and the mirror.

3. Portable Pedopowergraph as claimed in claim 1 wherein the device uses PR (the power ratio calculated based on actual foot pressure distribution on the foot sole), a parameter being intended to calculate comprehensive foot pressure which relates it to loss of foot sole sensation so as to detect foot at risk of ulcers.

4. Portable Pedopowergraph as claimed in claim 1 wherein the said device is linked via any computer and using a dedicated software to calculate the required parameters.

5. Portable Pedopowergraph as claimed in claim 1 wherein the output display (either in the monitor or printout) is colour coded so as to enable the doctor to easily identify the foot areas at risk.

6. Portable Pedopowergraph as described in the description and as illustrated by way of figures 3 to 7 of drawings accompanying the complete specification.