Proprioceptive ability - the sense of where body parts are located in space - is one of many factors thought to affect falls risk among the elderly. Active movement extent discrimination is an approach to measuring proprioception that is administered in an ecologically valid testing environment to better reflect the exercise of proprioceptive skills in daily life. The Active Movement Extent Discrimination Apparatus (AMEDA) was developed to objectively measure this proprioceptive discrimination. However, the current absolute identification testing protocol is cognitively demanding, and it yields results that are insufficiently reliable to assess performance at the individual level. The objectives of this pilot study were to test the reliability and feasibility of a proposed new AMEDA testing protocol and to explore how performance related to cognitive ability and any perceived dysfunction in the foot or ankle. We tested 42 participants (aged 19 - 94 years) three times on the ankle AMEDA using a newly developed protocol that asked participants to report whether a given angle of ankle inversion was shallower or deeper than the immediately preceding inversion. Participants also completed the Stroop test, as a measure of cognitive ability, and two validated questionnaires for identifying foot or ankle dysfunction (the Cumberland Ankle Instability Tool and the Foot and Ankle Ability Measure). The proportion of correct responses for the AMEDA test showed the expected sigmoid shape of the psychometric function as signal strength increased. The intraclass correlation coefficient measured over the three tests was 0.65 (95% confidence interval: 0.49 - 0.78), suggesting moderate reliability. We found a positive and statistically significant correlation between AMEDA performance and Stroop results but no relationship between the AMEDA score and questionnaire-measured foot or ankle dysfunction. This study confirmed that the alternative testing protocol was simple to administer and easily understood by participants.
Keywords: active movement extent discrimination; ankle function; falls in the elderly; proprioception; psychometric function.