Cobb angle measurements on digital radiographs using Bunnell scoliometer: Validation of the method.

Background: Electronic rulers on computer screen are used to measure the Cobb angle (CA) instead of traditional methods with rulers, protractors and pens. The variety of software used to assess radiographs might make the CA measurements cumbersome in everyday clinical practice.

Objective: The aim of the study was to verify the method of CA measurements on digital radiographs using Bunnell scoliometer (BS).

Methods: Eighty patients with idiopathic scoliosis were enrolled into the study. CA of each curve was measured by use of Centricity software and BS. CA on 30 randomly chosen patients were measured 3 times by one researcher using only scoliometer. Three researchers measured CA on the same 30 radiographs using BS.

Results: The mean CA of 224 curves measured by Centricity and BS were 29° ± 12.2° and 28° ± 11.7°, respectively. The ICC for agreement for 2 methods was 0.96 with SEM of 1.7°. Excellent intra- and interobserver reliability of CA measurements with scoliometer was noted: ICC of 0.96 with SEM of 1.4° and ICC of 0.93 with SEM of 1.9°, respectively.

Conclusions: The study revealed excellent reliability of CA measurements on digital radiographs using the BS. The proposed method of using the Bunnell scoliometer for CA measurements may be clinically useful.