Surface measurement of idiopathic scoliosis after VDS with rasterstereography.

Introduction: So far only radiometric and clinical methods have been availa ble for the evaluation of results after anterior scoliosis surgery. Rasters tereography has proved to be a reliable method for three-dimensional surfac e measurement of conservatively treated idiopathic scoliosis patients. Ther efore, patients treated operatively with anterior instrumentation were exam ined using rasterstereography to determine the three-dimensional correction of the spinal deformity. The aim was to measure back shape deformity, in p articular derotation, and thus cosmetic improvements. Methods: 31 patients with idiopathic thoracic, thoracolumbar and lumbar scoliosis (Cobb angle 57 .2 degrees) were examined with raster stereography preoperatively, postoper atively and after follow-up (25.2 months) in a standardized standing postur e. Standing radiographs were compared with raster stereography. Results: Th e mean Cobb angle was reduced from 57.2 degrees to 17.2 degrees, the raster stereographic maximal surface rotation from 16.5 degrees to 10.8 degrees, a nd the vertebral rotation according to Perdriolle from 29.2 degrees to 16.7 degrees. During followup the Cobb angle increased to 20.8 degrees, and sur face rotation to 11.3 degrees. Vertebral rotation remained constant. Lordos is and kyphosis angles changed only slightly. Conclusion: Rasterstereograph y is a suitable tool for analyzing the three-dimensional correction of spin al deformities after anterior scoliosis surgery. In particular, the cosmeti c improvement is clearly demonstrated. The measurement of surface rotation allows objective quantification of the obtained derotation.