A comparative study of axis-line-distance technique and Cobb method on assessing the curative effect on scoliosis.

PURPOSE

To compare the axis-line-distance technique (ALDT) and Cobb method for therapeutic evaluation of scoliosis.

METHODS

Fifty-seven patients with scoliosis were treated in our hospital, 47 underwent conservative bracing therapy and 10 underwent surgery. Based on 171 full-spine X-ray images obtained from these 57 cases before treatment, during conservative treatment or surgery, and at final follow-up after removing the brace or after surgery, two radiologists independently measured and calculated the correction rate during treatment and at final follow-up and the rate of correction loss after treatment with the ALDT and Cobb methods. Paired t-test and correlation analysis were performed.

RESULTS

Based on the ALDT, the lateral deviations of the apical vertebrae before treatment, during treatment, and at final follow-up were 31 ± 14 mm, 16 ± 8 mm, and 20 ± 8 mm, respectively; the correction rates during treatment and at final follow-up were 48.7 ± 21.2% and 37.6 ± 14.2%, respectively, and the rate of correction loss after treatment was 11.3 ± 6.5%. The Cobb angles of scoliosis before treatment, during treatment, and at final follow-up were 34 ± 14°, 19 ± 7°, and 22 ± 6°, respectively; the correction rates during treatment and at final follow-up were 44.4 ± 17.3% and 33.9 ± 14.4%, respectively, and the rate of correction loss after treatment was 11.4 ± 4.3%. Calculation of the correction rate during treatment differed significantly between the two radiologists when using the Cobb method (P < 0.05); their calculations of the correction rate and rate of correction loss were not different (P > 0.05). The measurement data of the two radiologists using the Cobb method showed a weak to moderate correlation (r = 0.49, 0.57, and 0.51, respectively). When using the ALDT, there were no significant differences between the radiologists in their measurements of the correction rate during and after treatment (P > 0.05) or in the rate of correction loss. The measurement data of the two radiologists using the ALDT showed a good to excellent correlation (r = 0.92, 0.93, and 0.90, respectively).

CONCLUSION

The ALDT is better than the Cobb method for therapeutic evaluation of scoliosis during treatment and at follow-up visits.