Foot pressure distribution: methodology and clinical application for children with ankle rheumatoid arthritis

INTRODUCTION:: Foot pressure measurements furnish information about distribution of pressures, forces, time and contact areas under the foot during standing and walking. Foot pressure measurement has been used in a number of rehabilitation and athletic applications in adults, however, little has been published regarding the clinical usefulness of this technology for children with disabilities. Children with juvenile rheumatoid arthritis (JRA) are reported to have various foot deformities and gait deviations and clinicians report that the children may have foot pain such as metatarsalgia. These may be treated with specially fitted shoes, shoe modifications or ankle foot orthoses. The purpose of this preliminary study was to describe the methodology used to quantify foot pressure distribution patterns and, further, to describe the patterns seen in individual children with JRA compared to aged matched typical children without JRA. METHODS:: Pressure, area and force were measured using the EMED-F system including a platform with 2048 capacitive pressure sensors and a computerized data collection and analysis system. Children were asked to walk comfortably and normally across the platform while time, pressure and area measurements were automatically taken. Other data collected were height and weight, observational gait analysis and lower extremity range of motion measurements. Data are reported for the entire foot, as well as particular areas of the foot that are of interest. For this study, eight discrete areas or masks were identified (medial and lateral heel, medial and lateral midfoot, first metatarsal, lateral four metatarsals, great toes and four lateral toes) for description. Information reported for each area and the total foot included force, peak pressure, total area, pressure time integral and force time integral. Data from three pairs of children were analysed and differences were described. RESULTS:: Several differences in the descriptive data were noted and will be highlighted. Children with JRA had striking asymmetries in several variables, higher peak pressures and in increased total foot pressure time integrals and force time integrals. This information is presented to improve our understanding of the patterns under the foot so that (1) appropriate treatment strategies for foot impairments may be better prescribed for children with JRA and (2) to assist in planning for treatment of gait abnormalities. This preliminary work will also form the basis for determining the clinically meaningful variables to consider in a larger study and statistical analysis.