A system for measuring pressures exerted by braces in the treatment of scoliosis

A battery-powered microcomputer system has been developed to continuously monitor pressures exerted by braces used to treat children with spinal deformities. Data are collected using an analog system with 16 transducers to measure either brace pressures or strap forces. Data acquisition is controlled by an MC68HC11 microcontroller. CMOS circuits are used to minimize power consumption, and the microcomputer and analog circuitry are kept in a low-power operating mode, except at the specific times when the measurements are taken. A programmable real-time clock controls the sample time and interval, and provides an interrupt to awaken the microcomputer from its low-power sleep mode. Data can be sampled with intervals ranging from 1 s to 1 day with the duration from 2.5 h to 2 weeks. At the end of each study, the data are transmitted to a host computer for analysis. Optimal use of all the features of the MC68HC11 enabled a system to be made which is small, lightweight, robust, and can be mounted on a brace worn by a child. Initial clinical studies suggest that mean brace pressures vary from 67 to 139 mmHg in the frontal plane and from 17 to 66 mmHg in the sagittal plane, and mean strap forces vary from 45 to 90 N.>