Axis-line-distance technique: a new method in scoliosis measurement

Objective: To investigate the clinical significance of a new method, axis-line-distance technique (ALDT), in scoliosis measurement. Methods: Thirty cases with idiopathic scoliosis were measured on two separate occasions by six observers with the Cobb technique and the ALDT on PACS workstation. The interval time between two measurement occasions were three weeks. The data were analyzed statistically with the paired-sample t-test. Results: (1) Concerning intraobserver variance in two measurement occasions, the minimum variance, the maximum variance and the average variance were 0, 24.00 degree, 5.71 degree ± 1.54 degree for Cobb technique and 0, 12.00 mm, (1.95±0.58 )mm for ALDT. There were significant measurement differences for four observers with Cobb method 39.00 degree ± 10.69 degree versus 36.50 degree ± 10.63 degree, 31.73 degree ± 10.96 degree versus 37.30 degree ± 9.65 degree, 32.03 degree ± 7.49 degree versus 27.86 degree ± 9.00 degree, 29.77 degree ± 8.87 degre versus 34.20 degree ± 7.26 degree, all P<0.05, except two attending physicians 36.63 degree ± 10.3 degree versus 37.13 degree ± 10.22 degree, 33.27 degree ± 10.09 degree versus 35.27 degree ± 9.71 degree. But there were no significant measurement differences for every observer with ALDT[(51.03±15.85) mm versus (50.73±15.50) mm, (52.40±14.88) mm versus (52.70±14.74) mm, (53.77±16.14) mm versus (53.60±15.33) mm, (54.07±15.36) mm versus (54.40±15.07) mm, (51.87±14.67) mm versus (51.77±14.46) mm, (52.93±13.88) mm versus (53.27±15.00) mm, all P>0.05]. (2) Concerning interobserver variances in six observers, the average measurement variance was 5.07 degree ± 0.35 degree for Cobb method, and (2.32±0.26) mm for ALDT. There were significant measurement differences for every observer using with Cobb method (36.63 degree±10.30 degree versus 33.27 degree ± 10.10 degre, 39.00 degree ± 10.69 degree versus 31.73 degree ± 10.96 degree, 32.03 degree ± 7.49 degree versus 29.78 degree ± 8.87 degree, 36.63 degree ± 10.30 degree versus 39.00 degree ± 10.69 degree versus 32.03 degree ± 7.48 degree, 39.00 degree ± 10.69 degree versus 32.03 degree ± 7.49 degree, all P<0.05). The measurement difference k om interobserver using with ALDT was significant (the first versus second or third observer, the third versus fifth observer), or no (the fifth versus first or sixth observer, the third versus fourth observer), which is not a direct relationship between the experience of the observer. Conclusion: The ALDT is worth applying and spreading, because it is more simple, more reliable and less error than the Cobb technique, as well as showing better intraobserver or interobserver reproducibility. (authors)