Reliability and validity of the Infoot 3D foot digitizer for normal healthy adults

Introduction: Abnormal foot posture and foot deformities have been identified as important factors in several foot and lower limb dysfunctions and pathologies. There is still no consensus over the optimum technique( s) to quantify these; hence a foot digitizer might be used as an objective measurement tool. The objective of this study is to check for the validity and the reliability of the Infoot digitizer. Methods: To investigate the validity of the Infoot digitizer in comparison with weight bearing X-rays and clinical measurements, both used in daily clinical practice, Pearson correlation coefficients were calculated and Bland-Altman plots were analysed. To investigate the reliability of the Infoot digitizer ICC, SEM, SDD and SDD% were calculated. Results and conclusions: Within this healthy population good validity could be demonstrated comparing the linear measurements from the Infoot 3D foot digitizer with the data from X-rays and clinical measurements. The majority of the obtained parameters proved to be very reliable.