Just enough measurement: a proposed paradigm for designing medical instrumentation

Kinetic Gait Analysis Using a Low-Cost Insole

Abnormal gait caused by stroke or other pathological reasons can greatly impact the life of an individual. Being able to measure and analyze that gait is often critical for rehabilitation. Motion analysis labs and many current methods of gait analysis are expensive and inaccessible to most individuals. The low-cost, wearable, and wireless insole-based gait analysis system in this study provides kinetic measurements of gait by using low-cost force sensitive resistors. This paper describes the design and fabrication of the insole and its evaluation in six control subjects and four hemiplegic stroke subjects. Subject-specific linear regression models were used to determine ground reaction force plus moments corresponding to ankle dorsiflexion/plantarflexion, knee flexion/extension, and knee abduction/adduction. Comparison with data simultaneously collected from a clinical motion analysis laboratory demonstrated that the insole results for ground reaction force and ankle moment were highly correlated (all >0.95) for all subjects, while the two knee moments were less strongly correlated (generally >0.80). This provides a means of cost-effective and efficient healthcare delivery of mobile gait analysis that can be used anywhere from large clinics to an individual's home.

Instrumented insole vs. force plate: a comparison of center of plantar pressure

Instrumented insoles allow analysis of gait outside of the confines of a motion analysis lab and capture motion data on every step. This study assesses the concurrent validity of center of plantar pressure (COPP) measurements during walking, and shows that our custom instrumented insoles compare favorably to an Advanced Mechanical Technology Inc. (AMTI) force plate in a clinical motion laboratory, particularly when the large difference in price is considered (an insole is nearly two orders of magnitude less expensive than a force plate). Deploying inexpensive insoles such as ours for ubiquitous health monitoring allows measurement of gait in more typical environments. This affords the opportunity to evaluate the gait of older adults in the home environment, and a future opportunity of providing real-time feedback corresponding to changes in gait.