5.1 Multi-axis force measuring platforms are used to measure the ground reaction forces produced at the interface between a subject's foot or shoe and the supporting ground surface. These platforms are used in various settings ranging from research laboratories to healthcare facilities. The use of force platforms has become particularly important in gait analysis where clinical evaluations have become a billable clinical service.
5.2 Of particular importance is the application of force platforms in the treatment of cerebral palsy (CP) (1, 2).3 An estimated 8,000 to 10,000 infants born each year will develop CP (3) while today’s affected population is over 764,000 patients (4). Quantitative gait analysis, using force platforms and motion capture systems, provide a valuable tool in evaluating the pathomechanics of children with CP. This type of mechanical evaluation provides a quantitative basis for treating neuromuscular conditions. In other words, surgical decisions are in part guided by information gained from the use of force platform measurements (5, 6).
5.3 Another application is treatment of spina bifida. According to the Gait and Clinical Movement Analysis Society (GCMAS) (7), an instrumented gait analysis is the Standard of Expert Care for children with gait abnormalities secondary to spina bifida. The main objective of diagnostic gait analysis is to define the pathological consequences of neural tube defects as they relate to gait. The use of instrumented gait analysis allows physicians to determine which surgical or non-surgical interventions would provide the best outcome.
5.4 More recently force platforms have been used for pre- and post-surgical evaluation of TKA (total knee arthroplasty) and THA (total hip arthroplasty) patients. Such data provides an objective measure of the mechanical outcome of the surgical procedure.
5.5 In addition to the clinical applications there are numerous medical and human performance research activities which rely on accurate measurement of ground reaction forces using multi-axis force platform measurement instruments.
5.6 As a standards organization ASTM has historically provided excellent standards for the calibration of force transducers and force-measuring instrumentation. Force platforms, however, are different from force transducers. Force platforms typically provide a large active working surface unlike force transducers which provide more or less point of interaction with the load-applying environment. Moreover, force platforms typically provide six-axis measurements and are expected to be used in environments causing multi-axial loading.