Evaluation of Three-Dimensional Correction of Idiopathic Scoliosis by Zielke Instrumentation Surface Measurement Using Videorasterstereography

So far only radiometric methods have been available for the evaluation of operating results with respect to the obtained correction. Rasterstereography has been proved to be a reliable method for three-dimensional surface measurement of brace-treated patients with ideopathic scoliosis. Therefore, patients treated operatively by Zielke instrumentation (VDS) were examined using rasterstereography regarding the three-dimensional correction of spinal deformity. The aim was to measure back shape deformity before and after VDS with a view to correction of abnormal vertebral rotation and reduction of thoracic and lumbar prominence. 24 patients with idiopathic thoracic and thoraco-lumbar scoliosis, who underwent VDS instrumentation at an average age of 16..9 years, were pre- and postoperatively measured by rasterstereography in a standardized standing posture. The patients were followed up for an average time of 19.6 months. Radiographs of the whole spine in standing posture and in two levels were made for comparision purposes. The following surface deformity parameters could be reduced: maximal lateral deviation of the spinal midline from 37.3mm to 20.4mm, maximum surface rotation from 16.1° to 10.3°. Measured radiometrically the mean Cobb angle of the primary curve could be reduced from 62.1° to 17.7° and the mean vertebral rotation ascertained according to Pedriolle from 28.6° to 17.4°. During follow-up the Cobb angle increased to 22.2°, the maximum surface rotation to 11.7° and the maximum lateral deviation to 22.8 mm. Vertebral rotation remained constant. Kyphosis and lordosis angles remained postoperatively essentially constant. By means of rasterstereography it is possible to document the three-dimensional correction of idiopathic scoliosis after VDS instrumentation in an objective manner. In particular, the cosmetic improvement as evident from the transverse profiles is clearly demonstrated. In addition reduction of surface rotation on the symmetry line allows an objective quantification of the obtained derotation. We consider the method a suitable tool- for back shape measurement of patients operatively treated by VDS.