Oxford Cobbometer Versus Computer Assisted-Software for Measurement of Cobb Angle in Adolescent Idiopathic Scoliosis

Objective: The objective was to compare Cobb angle measurements performed using an Oxford Cobbmeter and digital computer software (Surgimap) in a series of 83 AIS patients. Methods: Two independent observers measured the Cobb angles for 123 curves on 83 consecutive long radiographs of patients with AIS using both Oxford Cobbmeter and digital computer software (Surgimap). The measurements were repeated a week. Curves were classified according to the severity into mild, moderate, and severe. The results were statistically analyzed for intraobserver and interobserver reliability. Results: The mean Cobb angle was 48.12 degrees +/- 19.75 degrees (10.54 degrees - 110.76 degrees ). Globally the results of curve measurements were comparable between and within both observers using both methods, with small mean differences. According to ICC, there was high inter and intra-observer high agreement for both methods. All readings were > 0.9. There was a good inter-observer (kappa = 0.745, 0.693) and a very good inter-observer agreement (kappa = 0.810, 0.804) for both methods for curve classification. However, poor agreement was observed as regards to the measurement time, being less with Oxford Cobbometer. Conclusion: The results of this study indicate that the Surgimap digital computer software measurement is an equivalent measuring tool to the Oxford Cobbmeter in Cobb angle measurement. Both have high intra and inter-observer agreement for measurement and for curve classification, with small measurement differences. Oxford Cobbmeter is advantageous in being quicker, and therefore it is the method of choice for manual measurement, where PACS or digital system is not available.