Validation of the Matscan® Pressure Mat for Sway Analysis

PURPOSE: Sway analysis is a well accepted clinical evaluation. It is widely used as a clinical tool to evaluate equilibrium during static stance. Typically, sway analysis parameters are derived from the positions of the center of force (COF) using costly force plates that require special training to operate and are not easily moved. The Matscan®, a pressure mat developed by Tekscan, is a relatively inexpensive and portable device that allows precise measurement of vertical ground reaction forces and position of the COF. The purpose of this project was to validate the Matscan® for its application in sway analysis. METHODS: A total of 26 college age young adults participated in this study. All subjects had to stand statically under 3 conditions: 2-legged stance eyes open (YO) and eyes closed (YC) for 2 trials of 60 s, and 1-legged stance (dominant leg) eyes open (UP) for 2 trials of 30 s. For validation purposes, the Matscan® technology was evaluated (1) by testing the sheet sensor only on an AMTI strength gauge force plate, and (2) by using the Matscan® on the AMTI force plate. Validity analysis, using Pearson correlations and Bland and Altman analysis, was performed on the following sway parameters: area (area of the ellipse containing all of the COF positions acquired at 50 Hz), maximum AP and ML excursion (COF maximum excursion in the antero-posterior (AP) and medio-lateral (ML) directions). RESULTS: Correlations for the Area parameter between the sheet sensor and the AMTI measurements ranged from 0.89 for the YO condition to 0.94 for UP. For the AP and ML excursions, the correlations ranged from 0.85 (AP in UP condition) to 0.99 (ML in YC condition). Comparing the Matscan® to the AMTI measurements, the correlations ranged from 0.80 (AP in UP condition) to 0.98 (AP in YC condition). The Bland and Altman procedure also showed that, relatively to the AMTI measurements, the sheet sensor underestimated the area, AP and ML excursions by an average of 22%, 13% and 3% respectively. In contrast to the sheet sensor, the Matscan© compared to the AMTI produced a slight over-estimation of the measurements: area by 13% and AP and ML excursions by 2% and 4%. CONCLUSIONS: Our results show that the Matscan® can be used to produce valid measurements of sway parameters during a typical clinical balance evaluation.