Accuracy and reliability of a computer-aided measurement method of spinal length in adolescent idiopathic scoliosis

English Keywords:Scoliosis  Adolescent  Spinal length  Measurement method  Computer-aided

English Abstract:

  【Abstract】 Objectives: To evaluate the accuracy and reliability of a new computer-aided measurement method of spinal length in adolescent idiopathic scoliosis(AIS). Methods: Firstly, the method used to measure the spinal length was developed by Matlab 6.5, based on the digital photo of standing A-P radiographs of spine under the same condition. Using the program, four vertex points were selected from a vertebra, then a series of points were obtained on the center line. Based on these points, a spline interpolation algorithm was used to obtain smooth center line. Then, the spinal length could be calculated from these interpolated points. In order to assess the accuracy and reliability of the method, results of the means and standard deviations which measured five times repeatedly by one orthopedic surgeon using this method compared to results by two orthopedic surgeons using manual measurement method on five random digital photos. Forty-five patients(aged from ten to sixteen years old; 7 males, 38 females) with adolescent idiopathic scoliosis were selected, Cobb′s angle ranged from 10° to 45°, averaging at 32.5°. The spinal length of patients could be calculated by using this method. Three orthopedic surgeons performed the measurements independently and blindly in order to compare inter-observer reliability. And to compare intra-observer reliability, measurements were carried out two times on two different occasions by the same orthopedic surgeon. The interval between measurements was four weeks. Results: The measured results of five patients using computer-aided measurement method of spinal length were 325.8±0.46mm, 391.3±0.43mm, 476.7±0.04mm, 441.3±0.79mm, 432.8±0.50mm. And the measured results of the same five patients using manual measurement method by two different surgeons were 325.7±8.3mm, 390.9±7.6mm, 476.7±6.0mm, 441.5±8.2mm, 433.1±6.0mm and 326.2±5.9mm, 391.4±7.5mm, 476.1±5.8mm, 441.6±8.2mm, 432.9±5.8mm, respectively. Compared with the manual measurement results, the computer-aided measurement method of spinal length in adolescent idiopathic scoliosis was accurate, and the standard deviation of repeating measurement was lower. The spinal length of forty-five patients measured using computer-aided measurement method and mannual method was 404.7±43.2mm and 405.1±45.5mm respectively. There was no significant difference between the two methods through variance analysis or independent samples t test(P>0.05). Intraclass correlations for intraobserver at four weeks interval and interobserver agreements between three orthopedic surgeons in this measurement method of spinal length were 0.995 and 0.942 respectively(P<0.05). Conclusions: Compared to mannual method, the computer-aided measurement method of the spinal length in adolescent idiopathic scoliosis is accurate and reliable.