Digital stereophotogrammetry as a new technique to quantify truncal deformity: a pilot study in persons with osteogenesis imperfecta.

The objective of this pilot study was to determine the usability of stereophotogrammetry (SP) as a noninvasive technique for obtaining linear measures and anatomical data of the torso in people with osteogenesis imperfecta in comparison with clinical observations. Ten participants were recruited from subjects enrolled in ongoing institutional review board-approved osteogenesis imperfecta protocols at the National Institute of Child Health and Human Development. Using a Gulick tape measure, anthropometer, and the SP system proprietary software, linear measurements of the torso were taken. In addition, the presence or absence of specific torso deformities was documented from both clinical observation and evaluation of SP images. Measurements of torso diameter and circumference by SP demonstrated strong agreement with the manual measurements (intraclass correlation coefficient = 0.995 and 0.964, respectively). Substantial and statistically significant agreement was present between SP image evaluation and clinical observation for pectus carinatum (κ = 0.52 ± 0.23) and thoracic scoliosis (κ = 0.72 ± 0.12). The kappa values between clinical observation and SP evaluations of other torso deformities were not significant. The strong correlations and P values determined by this study demonstrate the potential value of SP in studying persons with truncal deformities. However, the weak agreement between SP and some clinical observations suggests that further development of SP image analysis tools is required before SP can be used as a standard method of diagnosis or assessment of treatment success.

Reliability, validity, and precision of an active stereophotogrammetry system for three-dimensional evaluation of the human torso.

To determine the reliability, stability, validity and precision of a stereophotogrammetry (SP) system for use in quantifying the complex three-dimensional structure of the human torso, we performed assessments of the system using images of geometric solids and a human-form mannequin. Analysis of geometric solids revealed excellent intra- and interrater reliability of the system for linear, surface area and volume measurements (r>0.99, P<0.001). Overall, no significant difference was found between SP and manual measurements (F=4.23, P>0.06). The system exhibited excellent stability in images of the mannequin over time (r>0.99). The limit of precision (error>5%) of the system to detect objects on the surface of the mannequin was estimated at an object size of 23.5cm(2) for surface area and 32mL for volume. These results demonstrate the capability of SP of the torso to be used as a reliable, stable and valid measure of torso morphology to be applied as a clinical outcome tool in studies of bony and soft tissue pathologies such as scoliosis, rib deformities, obesity or edema.