The Validity and Reliability of a low-cost handheld 3D Scanner for Use in Orthotics and Prosthetics

Background: 3D scanners are used to obtain three-dimensional (3D) shapes of body parts, offering an alternative to conventional techniques such as casting and a variety of potential advantages. However, 3D scanners are usually very expensive and not affordable and accessible for most orthotists and prosthetists, especially in developing countries. Therefore, this study aimed to evaluate the validity and reliability of a low-cost handheld and affordable 3D scanner (3Dsystems, ‘sense’) for use in orthotics and prosthetics. Methods: The validity and reliability of the 3D Sense scanner were assessed through repeated scanning and measurement of the predefined circumferences of the stumps of four transtibial amputees and 8 body cast models. Two assessors performed digital scanning and tape measurement on two different days, each consisting of three trials per condition/day. The reliability of the 3D sense scanner was assessed by investigating between trials, the assessors, and day reliability using Intraclass Correlation Coefficients. The standard error of measurement (SEM) was also calculated to assess measurement error. The validity of the 3D sense scanner was assessed using correlation analysis, mean percentage error (the mean differences between scanner and tape measure), and Bland-Altman statistics. Results: The 3D Sense scanner provides stumps and body cast model measurements with similar reliability to the tape measure. Reliability coefficients for the 3D scanner are relatively high (ICC). The ICCs all are near 1.0 and SEMs all range from 0.06 to 0.10. The 3D Sense scanner demonstrated excellent validity. There was a significant positive correlation between the 3D scanner and tape measure for both stumps and body cast models measurements (r>0.850; P<0.0001). The measurement error between the 3D scanner and tape measure is very low as indicated by mean differences close to zero. Conclusions: This study introduces a low-cost handheld and affordable 3D scanner, which has proven to be a valid and reliable clinical tool in orthotics and prosthetics. This 3D scanner would have extensive and powerful clinical applicability resulting in valid and reliable digital information of body segments for computer-aided design (CAD) of orthotics and prosthetics.