Reliability and validity study of measurements on digital photography to evaluate shoulder balance in idiopathic scoliosis

OBJECTIVE: To determine the validity of digital photography as an evaluation method for shoulder balance (ShB) in patients with idiopathic scoliosis. MATERIAL AND METHODS: A total of 80 patients were included (mean age 20.3 years; 85% women). We obtained a full x-ray of the vertebral column and front and back clinical photography for all patients. For antero-posterior x-rays we measured the proximal thoracic curve angles (CPT). To evaluate radiological shoulder balance we calculated the clavicle-rib intersection angle (CRIA) and T1-tilt. For clinical photography we measured shoulder height angle (SHA), axilla height angle (AHA) and the left right trapezium angle (LRTA). We analyzed the reliability of the different photographic measurements and the correlation between these and the radiological parameters. RESULTS: The mean magnitude of PTC, CRIA and T1-tilt were 19°, −0.6° and 1.4° respectively. Mean SHA from the front was −1.7°. All photographic measurements revealed an excellent-near perfect intra and inter-observer reliability in both photographic projections. No correlation was found between the ShB and the magnitude of the PTC. A statistically significant correlation was found between clinical balance of the shoulders and radiological balance (r between 0.37 and 0.51). CONCLUSIONS: Digital clinical photography appears to be a reliable method for objective clinical measurement of ShB. The correlation between clinical and radiological balance is statistically significant although moderate/weak. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13013-014-0023-6) contains supplementary material, which is available to authorized users.