The influence of posterior corrective surgery on surgical spinal height in adolescent idiopathic scoliosis

English Keywords:Adolescent idiopathic scoliosis  Surgical height gain  Correction surgery

English Abstract:

  【Abstract】 Objectives: To evaluate the spinal height recovery introduced by surgery in adolescent idiopathic scoliosis(AIS) patients, and to identify the predictive factors responsible for it. Methods: This study included 277 AIS patients undergoing correction surgery from January 2010 to June 2011. There were 173 single-curve(SC) and 104 double-curve(DC) idiopathic scoliosis cases. The mean magnitude of the major curves was 53.63°±15.38° in standing position(range 40°-140°) and 43.87°±15.01° in supine position(range 20°-124°). For each patient, the height(SH) of the spinal column was measured as the vertical distance from the upper endplate of T1 to the upper endplate of S1 in an full-length antero-posterior radiograph taken from a supine.postion before and after surgery, ΔSH was defined as the change in SH. Association between pre-op Cobb angle, corrected magnitude of Cobb angle, correction rate, pre-op SH, post-op SH and ΔSH were assessed partial correlation analysis. Results: The supine major Cobb angle was corrected to 15.69°±9.21°(range 4°-79°) postoperatively in single curve(SC) group, and 19.50°±13.07°(range 3°-95°) in DC group, with the correction rate of 69.7% and 65.5% respectively. In SC group, the average SH was improved from 41.29±2.96cm to 43.77±2.71cm after surgery, while the corresponding figures for DC group were from 39.97±3.26cm to 42.86±3.04cm. The height recovery averaged 1.97±0.79cm, 2.14±0.63cm, 2.52±0.65cm, 2.77±0.51cm, 3.92±0.61cm, 4.33±0.22cm, 4.85±0.22cm for Cobb angle within ≤30°, 31°-40°, 41°-50°, 51°-60°, 61°-70°, 71°-80°, >80° in SC group, respectively. Accordingly the figures of DC group were 2.37±0.60cm, 2.35±0.69cm, 2.56±0.53cm, 3.27±0.40cm, 3.79±0.94cm, 3.89±1.11cm, 5.46±0.91cm, respectively. There was a significant correlation between Height recovery and pre-op Cobb angle[SC group: r=0.702, P<0.001; DC group(major+minor): r=0.718, P<0.001], corrected magnitude of Cobb angle[SC group: r=0.659, P<0.001; DC group(major+minor): r=0.698, P<0.001] and post-op SH[SC group: r=0.182, P=0.017; DC group(major+minor): r=0.213, P=0.033]. However. It was not significantly related to the correction rate[SC group: r=0.083, P>0.05; DC group(major+minor): r=0.039, P>0.05] and pre-op SH[SC group: r=-0.082, P>0.05; DC group(major+minor): r=-0.047, P>0.05]. Conclusions: Posterior corrective surgery can significantly improve the spinal height in AIS patients. The major influential factors for ΔSH include pre-op Cobb angle and corrected magnitude of Cobb angle, while the post-op SH is no more than a secondary factor, nor was the correction rate of Cobb angle.