The reliability and reproducibility of sagittal spinal curvature measurement using the Microsoft Kinect V2

Abstract

BACKGROUND:

Abnormal sagittal spinal curvature is associated with pain, decreased mobility, respiratory problems and increased mortality. Time-of-flight technology of the Microsoft Kinect sensor can reconstruct a three-dimensional image of the back quickly and inexpensively.

OBJECTIVE:

To estimate the extent of the reproducibility of sagittal spine curvature measurement using the Microsoft Kinect sensor.

METHODS:

Simultaneous measurement of thoracic and lumbar spine using the Microsoft Kinect sensor in 37 participants. Two investigators gave standardised instructions and each captured 3 images. Thoracic kyphosis and lumbar lordosis angle indexes were calculated using maximum height divided by the length.

RESULTS:

Adult participants (mean age in years (SD) $=$ 51.7 (20.6); 57% female; BMI in kg/m ${}^2$ (SD) $=$ 24.9 (3.3)) kyphosis and lordosis indexes showed high intra-rater and inter-rater ICC values (0.960–0.973). The means of the first images from both raters had significantly larger kyphosis indexes compared to the second and third images, yet no difference between means in lordosis data.

CONCLUSIONS:

The results indicate that the Microsoft Kinect sensor has a reproducible method with high intra-rater and inter-rater reliability. The difference between the means over repeated measures suggest the second image capture is more consistent. It is a reproducible and quick method in clinical and research settings.