112. Utilizing a Flexible Pressure Grid to Quantify, Map, and Track Hand Grip Strength

PURPOSE: Although medical devices are available to measure hand forces during maximum voluntary contraction (MVC), motor deficits due to peripheral nerve injury can produce complex partial deficits of hand grip strength. To address this biotechnology gap, we have adapted a commercially flexible pressure grid to measure hand strength and developed metrics to assess both MVC and finger pinch grips. The purpose of this study was to assess the repeatability of a commercially available flexible pressure grid for MVC and develop quantitative metrics for finger pinch grips. METHODS: Twenty healthy adult participants performed trials of MVC by gripping the Tekscan flexible pressure grid with their entire hand as well as trials of kinetic individuation by gripping the Tekscan with the indicated finger and thumb without engaging other fingers at two visits separated by several weeks. Trials of MVC were also performed using the clinically used JAMAR digital dynamometer. Repeatability was assessed using intra-class correlation coefficients (ICC’s) and minimal detectable changes (MDC’s), and the Tekscan was compared to the JAMAR. An equation was developed to objectively assess pinch grip performance and produce force individuation scores on a scale of 0 (poor) to 1 (ideal), whereby participants achieved a higher score by performing the task without engaging the non-indicated fingers. RESULTS: Force data were utilized to develop heatmaps for both trials of MVC and pinch grips, highlighting natural variability in hand strength in the study population. The left (ICC 0.86; p<0.0001) and right (ICC 0.88, p<0.0001) hand MVC trials demonstrated good repeatability. The Tekscan’s sensitivity to small changes in forces inform the minimal clinically important difference for using this device to assess hand grip strength in the clinical setting (left MDC 65.1N; right MDC 63.9N). Trials of MVC with the Tekscan positively correlated with those of the JAMAR (R=0.68, p<0.0001). Force individuation scores followed a non-normal distribution between 0 and 1. CONCLUSION: Here we demonstrate the repeatability of the Tekscan to assess MVC and establish it performs similarly to the clinically used JAMAR dynamometer. An advantage of the Tekscan is its ability to localize force deficits to certain digits, and these data can be used to calculate force individuation scores providing an objective assessment of a participant’s ability to exert force with a targeted area of their hand. Force individuation scores and MVC data can be used in the future to track pre-, intra-, and post-operative motor performance in patients with peripheral nerve injury or other injury to the hand.