Digital Stereophotogrammetry as a New Technique to Quantify Truncal Deformity: A Pilot Study in Persons with Osteogenesis Imperfecta Lisa R Gabor, Andrew P Chamberlin, Ellen Levy, Monique Perry, Holly Cintas, and Scott M Paul
Article: Digital Stereophotogrammetry as a New Technique to Quantify Truncal Deformity: A Pilot Study in Persons with Osteogenesis Imperfecta
Authors: Lisa R Gabor, Andrew P Chamberlin, Ellen Levy, Monique Perry, Holly Cintas, and Scott M Paul
Source: American Journal of Physical Medicine & Rehabilitation
Date: October 2011
Abstract: The objective of this pilot study was to determine the usability of stereophotogrammetry (SP) as a non-invasive technique for obtaining linear measures and anatomical data of the torso in people with osteogenesis imperfecta (OI) in comparison to clinical observations. Ten participants were recruited from subjects enrolled in ongoing IRB-approved OI protocols at the National Institute of Child Health and Human Development (NICHD). 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 (ICC=0.995, 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) as well as thoracic scoliosis (κ = 0.72±0.12). The κ 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.
Methods: Participants received physical examinations as part of the regular protocol-specific data collection by two of the authors (S.P. and H.C.) who are associate investigators in the NICHD OI protocols. Authors S.P., H.C., E.L., and M.P. are all clinicians. S.P. and H.C. made the clinical observations and E.L. and M. P. evaluated the stereophotogrammetry images for this pilot study. Measurements of chest diameter (with the anthropometer) and circumference (with the Gulick anthropometric tape) of the subject’s torso were taken in a sitting position at the level of the xiphoid process. The xiphoid process was also marked with a surgical marking pen by author S.P. before the manual measurements were taken. Two authors (S.P. and H.C.) identified and agreed upon the presence or absence of pelvic asymmetry, pectus carinatum and excavatum, infraxiphoid and supraxiphoid depression, abdominal and thoracic protrusion, and scoliosis (thoracic, lumbar, and/or thoracolumbar) based on accepted clinical practices. Palpation was allowed as part of the clinical observations and scoliosis was determined from palpation and observation. Only asymmetries in the frontal plane were documented.
On the same day (subsequent to the above examination), four images were taken of the subject’s torso by SP cameras set in 360 degree mode (Figure 1). The subjects wore shorts and were seated with arms elevated to 90 degrees. Using the xiphoid landmark placed at the time of the clinical examination, author A.C. used the SP system software to take linear measurements of the anterior/posterior (AP) diameter and circumference of the subjects’ torso SP images. In addition, different evaluators (authors M.P and E.L), blinded to the clinical observations of S.P. and H.C. and to each other, made individual observations directly from the 3D image. Each identified the presence or absence of pelvic symmetry, pectus carinatum and excavatum, infraxiphoid and supraxiphoid depression, abdominal and thoracic protrusion, and scoliosis (thoracic, thoracolumbar, and/or lumbar) in the frontal plane (when applicable). Clinical observers and SP image evaluators were blinded to radiographs when diagnosing scoliosis. All evaluators are experienced clinicians with greater than ten years of experience in their field.