Plantar Pressure Difference: Decision Criteria of Motor Relearning Feedback Insole for Hemiplegic Patients

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1 22 4th Iteratioal Coferece o Bioiformatics ad Biomedical Techology IPCBEE vol.29 (22) (22) IACSIT Press, Sigapore Platar Pressure Differece: Decisio Criteria of Motor Relearig Feedback Isole for Hemiplegic Patiets Suwapor Sagha +, Surapog Chatpu, Wipawa Leelasamra 2 Istitute of Biomedical Egieerig 2 Departmet of Orthopaedic Surgery ad Physical Medicie, Faculty of Medicie, Price of Sogkla Uiversity, Sogkhla 9 Abstract. The feedback i the motor relearig approach is importat ad useful for hemiplegic patiet traiig. Platar pressure is cliically relevat to assess the foot fuctio. This study proposed the decisio criteria of isole feedback desiged for the motor relearig approach usig platar pressure. The operatig cocept of the isole feedback was also preseted. The Pedar-X system was used to measure the platar pressure i ormal people ad hemiplegic patiets. We calculated the platar pressure differece (PPD) from the maximum pressure picture (MPP) ad the mea value pressure (MVP). The values of PPD calculated from MPP were 4.9±.86% ad 29.8±.79% whereas the PPD calculated from MVP were 4.28±3.87% ad 2.6±9.47% i ormal perso ad patiet groups, respectively. We suggest usig the PPD calculated from MPP as the decisio criteria for the isole feedback because this value was clearly distiguished betwee groups, less variatio ad easy to obtai. However, the motor relearig program usig this isole feedback should be idividually desiged for patiet such as the set poit of PPD for the decisio criteria ad time of traiig. Moreover, it is ecessary to evaluate the patiet satisfactio after usig the feedback isole to improve the prototype of the shoes. Keywords: platar pressure, isole, feedback, motor relearig, hemiplegic. Itroductio A commo problem of hemiplegic patiets is the balace disorder which depeds o the area of damaged brai. Walkig patters i hemiplegic patiets are differet compared with ormal people []. The goal of walkig traiig i hemiplegic patiets is to make the platar pressure o a hemiplegic side to be similar to a ormal side. Motor relearig program techique focuses o the feedback to let the patiets kow the developmet of their traiig[2]. The platar pressure measuremet is cliically relevat to assess the foot ad akle biomechaical fuctio. Several studies reported that the Pedar-X system, a i-shoe dyamic pressure measurig system, has good repeatability ad accuracy i platar pressure measuremet i may coditios [3, 4]. Sesorembedded shoes with fuzzy logic algorithm developed by Kog ad Tomizuka was proposed to assess the abormalities i a huma gait []. Usig platar pressure measuremet, we coceptually developed the motor relearig isole feedback for hemiplegic patiets durig walkig traiig. Our study measured the platar pressure usig Pedar-X i ormal people ad hemiplegic patiets to idetify the decisio criteria of isole feedback. 2. Materials ad Methods 2.. Sesig material + Correspodig author. Tel.: + (66)744743; fax: + (66) address: dougtax_x@hotmail.com 29

2 The force sesitive resistor (FSR) is the pressure sesor used to measure the dyamic force. There is a type of resistor that the resistace chages whe the force or pressure is applied therefore its resistace depeds o force or pressure applied o the sesig area. Furthermore, FSR is very simple to use ad iexpesive compared to other types of sesors. The FRS characteristics are preseted i Table. Table : Force sesitive resistor (FSR) characteristics Overall legth Overall width Active area Force sesitive rage Force repeatability (Sigle part) Hysteresis diameter g to kg ± 2% + % 2.2. Isole structure Five FSRs are located uder the isole based o aatomical iformatio. The sesors are embedded i three areas; heel, metatarsal ad hallux. There are two sesors at the positio of heel, oe at the first metatarsal, oe at the fourth metatarsal ad oe at the area of hallux as show i Fig.. It has bee demostrated that higher pressure is foud i these three areas durig ormal activities [-8]. The isoles were attached to wearable measuremet system that measures the groud reactio force while walkig. The cotroller box cotaied a aalog to digital coverter is put udereath the isole ad coects to the sesors as preseted i Fig. 2. Fig. : Positios of FSR uder the isole. Alarm uit Fig. 2: Layout of the prototype for isole-feedback shoes Platar pressure measuremet We measured platar pressure usig the Pedar-X system i two experimetal groups; ormal perso ad hemiplegic patiet groups. A ormal perso group icluded males ad 9 females whereas a hemiplegic patiet group, attedig the service for physical therapy uit at Sogklaagarid hospital, had males ad 3 females. The iclusio criteria of ormal persos for this study were: age raged from 4 to 6 years, o previous surgery, o history of trauma ad o limb discrepacy. The lower limb discrepacy was defied by the equal legth of aterior superior iliac spie to medial malleolus while stadig betwee left ad right sides. The iclusio criteria for patiets ivolved i our study icluded a history of cerebrovascular 3

3 disease, age more tha 4 years ad a presece of balace disability. Subject was asked to wear sport shoes ad walk alog a distace about meters for 3 rouds. The experimet was repeated 3 times i each subject. At the ed of each time, subject took a rest for 3 miutes before startig the test agai. Platar pressures acquired from the Pedar-X system were i terms of the maximum pressure picture (MPP) ad mea value pressure (MVP). MPP is the maximum force values i each sesor divided by the umber of loaded sesor while MVP is the average of mea value i all frames of gait. We calculated the differece of platar pressure i term of MPP ad MVP either ormal or hemiplegic patiet groups Data processig cocept The operatig cocept of the isole feedback after data acquisitio is show i the flowchart of Fig. 3. I brief, the average pressure of each side will be calculated if all sesors have value. The percetage of the platar pressure differece (PPD) was the calculated as expressed i (). The decisio criteria of the isole feedback for the motor relearig were based o the PPD. Therefore, we used PPD i a ormal group as a target of the motor relearig program. If the PPD obtaied from the sesors is greater tha the target PPD, the alarm uit will ackowledge the patiets that their platar pressure o both sides is differet ad eeds to be adjusted. 2( P P ) Left Right PPD () P + P Left Right Start Receive values from sesors P L,i, P R,j ; I,j: No Yes Calculate average platar pressure P Left PL, i ; ad P Right P R, j ; j i Yes PPD < PPD Target No Alarm O LED o or Beep soud Fig. 3: Flow chart of data processig for isole feedback. 3. Results 3.. Percetage of platar pressure differece PPD durig walkig calculated from MPP ad MVP betwee left ad right sides is preseted i Fig.4. There were statistically sigificat differeces i both MPP ad MVP betwee the ormal perso group ad the hemiplegic patiet group. The values of PPD calculated from MPP were 4.9±.86% ad 29.8±.79% i ormal perso ad patiet groups. I additio, the values of PPD calculated from MVP were 4.28±3.87% ad 2.6±9.47% i ormal perso ad hemiplegic patiet groups. It clearly idicates that the PPD was higher i the hemiplegic patiets ad sigificatly differet compared to ormal people (p<.). Therefore, we ca use PPD to idetify hemiplegic patiets ad be the decisio criteria for the motor relearig program. Whe we focused PPD i the ormal perso group, we foud that PPD calculated from MPP was ot varied due to the age, ulike PPD calculated from MVP as demostrated i Fig.. The mea value of PPD calculated from MPP was ~% i all three rages of age. I cotrast, it seems that the mea value of PPD 3

4 calculated from MVP icreased whe the age icreased. However, this result might be related to less loaded areas for platar pressure whe people get older. 4 p<. Normal (24) Patiet (8) p<. PPD(%) 3 2 MPP MVP Fig. 4: The percetage of platar pressure differece (PPD) while walkig calculated from MPP ad MVP i ormal persos ad hemiplegic patiets. PPD(%) years old (9) 46- years old (2) - years old (3) MPP MVP Fig. : The percetage of platar pressure differece (PPD) while walkig calculated from MPP ad MVP i ormal persos classified by age Weight testig of isole feedback Usig a castig foot combied with fitess drum bells as the testig weights, it was foud that the output voltage from the cotroller box liearly icreased with the testig weight as show i Fig.6. However, there was residue output voltage eve though there was o weight o the sesors. 2 V out (V) 7 V out 8.42W+69.9 r Fig. 6: The relatioship betwee testig weights ad output voltages of the cotroller box 4. Discussio ad Coclusios Weight (kg) I this paper, we measured platar pressures ad foud that there was a vast differece i the groud reactio force betwee hemiplegic side ad ormal side durig walkig i stroke patiets compared to that i 32

5 ormal persos[9]. We therefore proposed the value of PPD to be used as decisio criteria of isole feedback i motor relearig of hemiplegic patiets. The value of PPD calculated from MVP was lower tha that calculatio from MPP due to the calculatio method of mea ad peak values. The variatio of PPD i patiet group was greater compared to the ormal group. This variatio was the result of severity ad traiig period of patiets[]. Our results sigificatly showed that hemiplegics patiets had PPD calculated from either MPP or MVP about 2% to 2% higher tha ormal persos. We suggest usig the PPD calculated from MPP as the decisio criteria for the isole feedback because this value had more differet betwee groups ad ot complicate to obtai. Therefore, i order to perform a motor relearig program for the hemiplegic patiet, it is ecessary to gradually lower, stepwise-like patter, the platar pressure differece betwee a hemiplegic side ad a ormal side toward the target value of ormal perso (PPD%) [2]. However, the motor relearig program usig this isole feedback should be idividually desiged for patiet such as the set poit of PPD for the decisio criteria ad time of traiig. Therefore, it is importat to kow about the age, symptom, severity ad therapeutic program of patiet. I future work, we would like to validate our isole feedback with the decisio criteria of PPD durig walkig of ormal people ad patiets. We would also like to icrease the umber of subjects, both ormal people ad hemiplegic patiets, to fialize the target PPD. Moreover, it is ecessary to evaluate the patiet satisfactio after usig the feedback isole to improve the prototype of the shoes.. Ackowledgemets The authors would like to thak the voluteers ad patiets i their cotributio for the platar pressure measuremet. 6. Refereces [] G. Gille, Stroke rehabilitatio : a fuctio-based approach. Elsevier. 2 [2] D.Y. Cha, C.C. Cha, ad D.K. Au. Motor relearig programme for stroke patiets: a radomized cotrolled trial. Cliical Rehabilitatio. 26, 2: 9-2. [3] Z. Pataky, D. De Leo Rodriguez, L. Allet, A. Golay, M. Assal, J.P. Assal, ad C.A. Hauert. Biofeedback for foot offloadig i diabetic patiets with peripheral europathy. Diabetic Medicie. 2, 27(): [4] A.K. Ramaatha, P. Kira, G.P. Arold, W. Wag, ad R.J. Abboud. Repeatability of the Pedar-X i-shoe pressure measurig system. Foot ad Akle Surgery. 2, 6(2): [] K. Kyougchul, ad M. Tomizuka. Estimatio of abormalities i a huma gait usig sesor-embedded shoes. IEEE/ASME Iteratioal Coferece o Advaced Itelliget Mechatroics. 28, pp [6] L. Shu, T. Hua, Y. Wag, Q. Li, D.D. Feg, ad X. Tao. I-shoe platar pressure measuremet ad aalysis system based o fabric pressure sesig array. IEEE Trasactios o Iformatio Techology i Biomedicie. 2, 4(3): [7] M.J. Hessert, M. Vyas, J. Leach, K. Hu, L.A. Lipsitz, ad V. Novak. Foot pressure distributio durig walkig i youg ad old adults. BMC Geriatr. 2, : 8. [8] E. Kellis. Platar pressure distributio durig barefoot stadig, walkig ad ladig i preschool boys. Gait Posture. 2, 4(2): [9] C.L. Che, K.T. Yeug, C.H. Wag, H.T. Chu, ad C.Y. Yeh. Aterior akle-foot orthosis effects o postural stability i hemiplegic patiets. Archives of Physical Medicie ad Rehabilitatio. 999, 8(2): [] K.N.K. Fog, C.C.H. Cha, ad D.K.S. Au. Relatioship of motor ad cogitive abilities to fuctioal performace i stroke rehabilitatio. Brai Ijury. 2, ():