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Using objective measurements from pedobarograph data to assess foot deformities
94
Gait & Posture
USING
OBJECTIVE
1995; 3: No 2
MEASUREMENTS TO ASSESS FOOT
FROM PEDOBAROGRAPH DEFORMITIES
DATA
m
Miller. M.&*. Patrick Castagno, M.S.*. James Richards, Ph.D.‘*. Glenn Lipton, B.S.* *Alfred I. duPont Institute. Wilmington. DE 19899 **University of Delaware, Newark, DE 19716
total pressure. Z-way ANOVA Significant arthrodesis
Peak values from within each area were analyzed with group and region comprising the factors. differences groups in
Introduction Pedobarographs are commonly used to measure the pressure distribution histories under the sole of the foot during gait. However. these pressure measurements are often difficult to analyze in an objective manner, and establishing a link between the pedobarograph data and clinically significant deformities in the foot can be extremely challenging. The goal of this project was to develop an objective methodology to assess the pressure distribution histories under the sole of the foot and relate these to a clinically slgniflcsnt deformity in the feet. Methodology Subjects consisted of 65 Individuals with apparently normal feet and 45 patients who were being evaluated for the outcome of triple arthrodesis. All subjects were between 9 and 26 years of age. ‘Ihe pedobarograph was obtained at a rate of 6Ohz utilizing a 49x49cm floor mat manufactured by Tekscan@. Patients were asked to walk across the mat at a comfortable rate of speed, and standard data files were collected using the manufacturer’s program. Projectspecific software was created to allow the pressure/time histories to be extracted from the area of the mat that contained the full length and width dimensions of the subject’s foot. Pressure/time histories from this area were then partitioned into thirds along the longitudinal axis of the foot. and the front two of these partitions were subsequently divided Into medial and lateral halves. This provided pressure distributions for five segments including a heel segment, a medial forefoot segment. a lateral forefoot segment, a medial midfoot segment. and a lateral midfoot segment. The pressures inside each of these areas were summed, dilated to 50 samples, plotted over time. and expressed as a percentage of the
Measurement Of Dynamic Pressures At The Shoe-Foot Interface During Normal Walking With Various Foot Onhoses Using A New Version Of The FSCAN System Melanie
Brown.
NIAMS,
MD
Bethesda,
Albert
MD Tufts University/New Esquenazi, MD Moss Rehabilitation
MD
Sally Rudicel,
England Hospital.
Medical
Center, Boston, MA
Philadelphia,
PA
INTRODUCTION Foot onhoses
are currently used to redistribute pressures at the shoe-foot interface. Their use is particularly prevalent in the treatment of foot disease associated with diabetes and rheumatoid arthritis’. Although foot onhoses are used routinely in clinical practice, there is very little scientific evidence suppotting the efficacy of their use. In recent years an ultrathin (7/1000 inch thick) in shoe pressure transducer called the FSCAN sensor (I&scan, Boston, MA) has become commercially available. This system was initially evaluated by Rose, Feiwell, and Cracchiolo in 1992’. They concluded that, in spite of significant measurement variability and limited durability, the FSCAN system “could be useful for making comparisons and evaluating changes in a well controlled clinical study.” Since 1992, the Tekscan corporation has tried to address these difficulties with the FSCAN system. The purpose of this study was to use the new version of the FSCAN system to evaluate the efficacy of pressure redistribution for various onhoses as compared to control (no onhosis).
Results were found between the areas of the heel
3. Midfoot
Medial
using
the normal and triple and the medial midfoot. Patients who underwent triple arthrodesis showed significantly lower peak pressures in the heel region and significantly greater peak pressures in tbe midmedial region of the foot. Graphical analysis of the data showed marked differences in the loading The outcome of the individuals with triple arthrodesis correlated well with X-ray measurements of the residual deformity. Mscussion
It is apparent from this analysis that the triple arthrodesis procedure did not completely correct the foot. It was concluded that the analysis of pressure/time histories in the five defined regions of tb’ foot provides a clinically relevant and objective method for distinguishing normal patients from triple arthrodesis patients. It is likely that this method will perform as well for the analysis of additional types of foot abnormalities and for determining the effectiveness of specific surgical procedures. Heel
Betts.
R. et.& Quantitation 1:113-124,
Southwell. Plate
Analysis of the 1980.
References of Pressure and Loads Dynamic Distribution.
Under the Foot. Clin Phys Physiol
R. et.al.. Triple Arthrodesis: A Long-term Analysis, Foot and Ankle. 2: 15-24, 1981.
Tenuta. J. et.al.. with Cerebral
Longterm Follow-up Palsy. J ofPed Orth
of Triple 13:713-716,
Study
Arthrodesis 1993.
Part II: Meas.
with
force
in Patients
RESULTS Sensor to sensor measuremenr variabiliry deviated from 11% above fhe nxiu> 10 18% below the mean, with an average deviation from the mean of 3%. Durability testing revealed no significant dlffeerrnce between the average peak pressure reading measured during the first nine steps rake” and the last nine steps taken. in the scrirs of 300 gait cycles. The average stance time changed by less than 3.8% while wearing an onhosis verws control (no onhosis). Decreases in peak pressure wre found in the forefoot region while wearing the plastic foot onhosis (14%), and in the heel region while wearing the Plastizoate orthosis (10%). Increases in peak pressure were found in the midfoot region while wearing rhe cork and the plastic foot onhoses (22% and 13% respectively). Decreases in the pressure time integral were found in the heel and lateral metatarsal head regions when wearing any one of the four foot orthoses that were evaluated. Increases in the pressure time integral were found in the midfoot and lesser roe regions when wearing any one of the four foot onhoses that were evaluated.
METHODOLOGY Ten normal subjects participated in this study. Sensor to sensor measurement variability was evaluated by recording four walking trials for each of twenty different FSCAN sensors, in a single subject. The durability of a single FSCAN sensor was evaluated by recording the pressures at the shoe-foot interface during 300 gait cycles in a single subject. Each one of the 10 subjects walked without an orthosis (control), with a custom molded Plastizoate orthosis, and with appropriately sized, off the shelf, Spenco, cork, and plastic onhoses. Version 3.622 of the FSCAN system was used to determine the stance time, peak pressure, and the pressure time integral at eight different regions of the foot (great toe, forefoot, midfoot, heel, fist metatarsal head, lateral metatarsal heads, lesser toes, and total foot). The pressure data for each subject was normalized by dividing by the subject’s body weight. Results were compared to control via nonparametric paired t-testing and reported as percent change from control.
a
DISCUSSION The findings suggest that, among the onhoses evaluated, the cork and pIastic foot orthoses redistributed pressure, From the forefoot and heel to the midfoot, more effectively than the Plastlzoate and Spenco foot otthoses. There is also evidence that, in spite of improvements, the FSCAN system continues to be limited by measurement deviations between sensors. ACKNOWLEDGEMENTS This study was performed at the Moss Rehabilitation Hospital Gait Laboratory The authors would like to thank Barbara Hirai and Joe DuPree for theu assistance. REFERENCES 1 Hicks, IE: Archives Of Physical Medicine And Rehabilitation, 2 Rose, NE: Foot And Ankle, 13(5):263-270, 1992.
70(5):S210-217,
1989
Gait & Posture
USING
OBJECTIVE
1995; 3: No 2
MEASUREMENTS TO ASSESS FOOT
FROM PEDOBAROGRAPH DEFORMITIES
DATA
m
Miller. M.&*. Patrick Castagno, M.S.*. James Richards, Ph.D.‘*. Glenn Lipton, B.S.* *Alfred I. duPont Institute. Wilmington. DE 19899 **University of Delaware, Newark, DE 19716
total pressure. Z-way ANOVA Significant arthrodesis
Peak values from within each area were analyzed with group and region comprising the factors. differences groups in
Introduction Pedobarographs are commonly used to measure the pressure distribution histories under the sole of the foot during gait. However. these pressure measurements are often difficult to analyze in an objective manner, and establishing a link between the pedobarograph data and clinically significant deformities in the foot can be extremely challenging. The goal of this project was to develop an objective methodology to assess the pressure distribution histories under the sole of the foot and relate these to a clinically slgniflcsnt deformity in the feet. Methodology Subjects consisted of 65 Individuals with apparently normal feet and 45 patients who were being evaluated for the outcome of triple arthrodesis. All subjects were between 9 and 26 years of age. ‘Ihe pedobarograph was obtained at a rate of 6Ohz utilizing a 49x49cm floor mat manufactured by Tekscan@. Patients were asked to walk across the mat at a comfortable rate of speed, and standard data files were collected using the manufacturer’s program. Projectspecific software was created to allow the pressure/time histories to be extracted from the area of the mat that contained the full length and width dimensions of the subject’s foot. Pressure/time histories from this area were then partitioned into thirds along the longitudinal axis of the foot. and the front two of these partitions were subsequently divided Into medial and lateral halves. This provided pressure distributions for five segments including a heel segment, a medial forefoot segment. a lateral forefoot segment, a medial midfoot segment. and a lateral midfoot segment. The pressures inside each of these areas were summed, dilated to 50 samples, plotted over time. and expressed as a percentage of the
Measurement Of Dynamic Pressures At The Shoe-Foot Interface During Normal Walking With Various Foot Onhoses Using A New Version Of The FSCAN System Melanie
Brown.
NIAMS,
MD
Bethesda,
Albert
MD Tufts University/New Esquenazi, MD Moss Rehabilitation
MD
Sally Rudicel,
England Hospital.
Medical
Center, Boston, MA
Philadelphia,
PA
INTRODUCTION Foot onhoses
are currently used to redistribute pressures at the shoe-foot interface. Their use is particularly prevalent in the treatment of foot disease associated with diabetes and rheumatoid arthritis’. Although foot onhoses are used routinely in clinical practice, there is very little scientific evidence suppotting the efficacy of their use. In recent years an ultrathin (7/1000 inch thick) in shoe pressure transducer called the FSCAN sensor (I&scan, Boston, MA) has become commercially available. This system was initially evaluated by Rose, Feiwell, and Cracchiolo in 1992’. They concluded that, in spite of significant measurement variability and limited durability, the FSCAN system “could be useful for making comparisons and evaluating changes in a well controlled clinical study.” Since 1992, the Tekscan corporation has tried to address these difficulties with the FSCAN system. The purpose of this study was to use the new version of the FSCAN system to evaluate the efficacy of pressure redistribution for various onhoses as compared to control (no onhosis).
Results were found between the areas of the heel
3. Midfoot
Medial
using
the normal and triple and the medial midfoot. Patients who underwent triple arthrodesis showed significantly lower peak pressures in the heel region and significantly greater peak pressures in tbe midmedial region of the foot. Graphical analysis of the data showed marked differences in the loading The outcome of the individuals with triple arthrodesis correlated well with X-ray measurements of the residual deformity. Mscussion
It is apparent from this analysis that the triple arthrodesis procedure did not completely correct the foot. It was concluded that the analysis of pressure/time histories in the five defined regions of tb’ foot provides a clinically relevant and objective method for distinguishing normal patients from triple arthrodesis patients. It is likely that this method will perform as well for the analysis of additional types of foot abnormalities and for determining the effectiveness of specific surgical procedures. Heel
Betts.
R. et.& Quantitation 1:113-124,
Southwell. Plate
Analysis of the 1980.
References of Pressure and Loads Dynamic Distribution.
Under the Foot. Clin Phys Physiol
R. et.al.. Triple Arthrodesis: A Long-term Analysis, Foot and Ankle. 2: 15-24, 1981.
Tenuta. J. et.al.. with Cerebral
Longterm Follow-up Palsy. J ofPed Orth
of Triple 13:713-716,
Study
Arthrodesis 1993.
Part II: Meas.
with
force
in Patients
RESULTS Sensor to sensor measuremenr variabiliry deviated from 11% above fhe nxiu> 10 18% below the mean, with an average deviation from the mean of 3%. Durability testing revealed no significant dlffeerrnce between the average peak pressure reading measured during the first nine steps rake” and the last nine steps taken. in the scrirs of 300 gait cycles. The average stance time changed by less than 3.8% while wearing an onhosis verws control (no onhosis). Decreases in peak pressure wre found in the forefoot region while wearing the plastic foot onhosis (14%), and in the heel region while wearing the Plastizoate orthosis (10%). Increases in peak pressure were found in the midfoot region while wearing rhe cork and the plastic foot onhoses (22% and 13% respectively). Decreases in the pressure time integral were found in the heel and lateral metatarsal head regions when wearing any one of the four foot orthoses that were evaluated. Increases in the pressure time integral were found in the midfoot and lesser roe regions when wearing any one of the four foot onhoses that were evaluated.
METHODOLOGY Ten normal subjects participated in this study. Sensor to sensor measurement variability was evaluated by recording four walking trials for each of twenty different FSCAN sensors, in a single subject. The durability of a single FSCAN sensor was evaluated by recording the pressures at the shoe-foot interface during 300 gait cycles in a single subject. Each one of the 10 subjects walked without an orthosis (control), with a custom molded Plastizoate orthosis, and with appropriately sized, off the shelf, Spenco, cork, and plastic onhoses. Version 3.622 of the FSCAN system was used to determine the stance time, peak pressure, and the pressure time integral at eight different regions of the foot (great toe, forefoot, midfoot, heel, fist metatarsal head, lateral metatarsal heads, lesser toes, and total foot). The pressure data for each subject was normalized by dividing by the subject’s body weight. Results were compared to control via nonparametric paired t-testing and reported as percent change from control.
a
DISCUSSION The findings suggest that, among the onhoses evaluated, the cork and pIastic foot orthoses redistributed pressure, From the forefoot and heel to the midfoot, more effectively than the Plastlzoate and Spenco foot otthoses. There is also evidence that, in spite of improvements, the FSCAN system continues to be limited by measurement deviations between sensors. ACKNOWLEDGEMENTS This study was performed at the Moss Rehabilitation Hospital Gait Laboratory The authors would like to thank Barbara Hirai and Joe DuPree for theu assistance. REFERENCES 1 Hicks, IE: Archives Of Physical Medicine And Rehabilitation, 2 Rose, NE: Foot And Ankle, 13(5):263-270, 1992.
70(5):S210-217,
1989