A Holter type system for recording plantar pressures: Development and clinical applications

Current foot pressure monitoring systems have short data capture intervals and permit recording of only a few consecutive steps with monitoring equipment frequently tethered to the subject by cable. These contemporary systems are unable to monitor in-shoe plantar pressures for more than a few minutes. Inherent gait variability requires that large numbers of steps be examined for reliable analysis and characterization. In order to fulfill demand criteria not available in current commercial systems, a Holter type, microprocessor based, portable, in-shoe, plantar pressure data acquisition system has been developed. The system is capable of recording continuous pressure data between the sole of the foot and the shoe for up to 16 hours during normal daily activities. The extended recording and processing capacity of the system allows quantitative analysis of cumulative plantar pressure and temporal gait data necessary for characterization of event-related alterations in plantar pressures. The system is fully portable, subjects carry it in a belt pack and ambulate freely without any disruption to their normal gait pattern. The system was applied clinically to collect pressure distribution data from several patient populations in order to quantitatively characterize the effects of treatment which have not been reported in the literature. Two studies of pedorthic use in adults were performed. The use of metatarsal and scaphoid pads were examined to determine and characterize the resulting plantar pressure redistribution. With metatarsal pad use, pressure redistribution was characterized with increased peak loads delivered to the normally unloaded metatarsal shaft region, and decreased peak loads delivered to the more peripheral areas. This redistribution is supportive of the postulate that decreasing the metatarsal prominence loads (peripheral pad areas) is effective in reducing pain associated with metatarsalgia and Morton\u27s neuroma. Scaphoid pad use resulted in peak load increases at the lateral foot and peak load decreases at the medial and calcaneal regions of the foot. The system was also implemented clinically in the evaluation of the planovalgus feet in children with cerebral palsy. A group of children with planovalgus foot deformity secondary to spastic cerebral palsy was evaluated preoperatively and following subtalar fusion for correction of the foot deformity. Comparing pre- and postoperative results, the Holter type data acquisition system has been successful in showing quantifiable differences in loading of the foot after surgery. These differences were consistent with the changes noted on the single step analyses; that is, at the midfoot the peak pressures, sensor contact durations, and pressure-time integrals were diminished medially and increased laterally. The same three metrics were also diminished at the first metatarsal head with increases at the more lateral heads