Validity and reliability of an iPad with a three-dimensional camera for posture imaging

Abstract

Background: It is important to quantify a static posture to evaluate the need for and effectiveness of interventions such as physical management, physiotherapy, spinal orthosis or surgical treatment on the alignment of body segments. Motion analysis systems can be used for this purpose, but they are expensive, require a high degree of technical experience and are not easily accessible. A simpler method is needed to quantify static posture. Research objective: Assess validity and inter and intra rater reliability using an iPad with a 3-D camera to evaluate posture and postural deformity. Method: A 3-D model of a lying posture, created using an iPad with a 3-D camera, was compared to a Qualisys motion analysis system of the same lying posture, the latter used as the gold standard. Markers on the trunk and the leg were captured by both systems, and results from distance and angle measurements were compared. Results: All intra-class correlation coefficient values were above 0.98, the highest systematic error was 4.3 mm for length measurements and 0.2° for angle measurements. Significance: A 3-D model of a person, with markers on anatomical landmarks, created with an iPad with a 3-D camera, is a valid and reliable method of quantifying static posture. Conclusion: An iPad with a 3-D camera is a relatively inexpensive, valid and reliable method to quantify static posture in a clinical environment.