Adolescent Idiopathic Scoliosis, Skeletal Maturity, Surgery—Study Statistical Analysis

Meeting highlight from the American Association of Orthopaedic Surgeons 2017 Annual Meeting

This continues the article, Surgery for Adolescent Idiopathic Scoliosis Patients After Skeletal Maturity: Now or Later? that was presented by Baron S. Lonner, MD, at the American Association of Orthopaedic Surgeons 2017 Annual Meeting. To view beginning of Dr. Lonner’s talk, click here.

Statistical Analysis

Descriptive statistics were used to summarize the distributions of variables given as means and standard deviations. Two-sided Student’s t-test (for normally distributed data) and Mann-Whitney-Wilcoxon test (for nonparametric data) were used to determine the statistical differences in continuous data.

Data being calculated and entered into a computerOnly available data was analyzed and missing data was ignored. Photo Source: LifetimeStock.Chi-square test was performed for categorical data analyses. Under 5% of values were missing in all radiographic, operative, and quality of life outcome measurements. Missing data was likely due to measurement difficulties and were completely random.

Only available data was analyzed and missing data was ignored. Statistical Package for the Social Sciences (SPSS) version 19.0 (IBM) was used for statistical analysis.


Final gender- and curve-matched cohorts consisted of 28 cases of adult idiopathic scoliosis (average 43.7, range 23-70 years of age). Fifty-six cases of adolescent idiopathic scoliosis (average 15.7, range 11-19 years of age), 93% were female patients. The cohort with adolescent idiopathic scoliosis were lower in body mass index than that with adult idiopathic scoliosis (21.8 vs 26.0; P=.0018).

Two-year postoperative major Cobb (21.8-degrees ± 13.5-degrees vs 19.0-degrees ± 5.9-degrees) and percent correction (61.7 ± 24.1 vs 61.8 ± 11.2) were similar between patients with adult and adolescent idiopathic scoliosis.

Operative time, however (414.3 ± 155.9 vs 281.3 ± 130.4 minutes; P=.0001), estimated blood loss (1403.6 ± 1101.5 vs 722.9 ± 470.1 mL; P = .0027), percent estimated blood loss (35.1 ± 29.2 vs 20.3 ± 13.8; P = .0027), length of stay (6.3 ± 1.9 vs 5.3 ± 1.2 days; P = .0043), and total spine levels fused (12.9 ± 2.9 vs 9.4 ± 2.6 levels; P<.0001) were greater for adult than those for adolescent idiopathic scoliosis.

The adult cohort received more anterior-posterior combined procedures (n=8; 28.6%) than the cohort with adolescent idiopathic scoliosis, all of whom underwent posterior procedure only (P<.0001). Data on osteotomy utilization was not uniformly available.

Differences in percent estimated blood loss, total operative time, and length of stay between the two cohorts were abolished after normalization by the number of levels fused (2.6 ± 1.7 vs 2.1 ± 1.2). Ten (36%) of patients with adult idiopathic scoliosis were fused to the pelvis compared to none in patients with adult idiopathic scoliosis (P<.0001).

In the analysis by Lenke curve type, the following were found: In Lenke 1 and 2; and Lenke 3, 4 and 6 groups, operative time and number of levels fused were significantly greater in the adult idiopathic scoliosis cohort, whereas, estimated and percent of estimated blood loss were also higher in the adult idiopathic scoliosis cohort Lenke 5 group.

Normalized percent estimated blood loss, and total operative time did not show significant differences between the two cohorts in any of the Lenke curve types. Longer normalized length of stay was observed in the adolescent idiopathic scoliosis cohort in the Lenke 5 group only.

The major complication rate was higher for adult than for adolescent idiopathic scoliosis (25% vs 5.4%, respectively; P=.0138). The adult idiopathic scoliosis cohort experienced three complications, which were one cardiopulmonary, one deep infection, and one instrumentation failure, resulting in reoperation (10.7%), whereas two complications (3.6%), one pseudoarthrosis and one instrumentation failure, in the adolescent idiopathic scoliosis cohort required reoperation (difference not significant).

Normalized preoperative and 2-year postoperative SRS-22r scores were worse in all domains in cases of adult than adolescent idiopathic scoliosis. Patients with adult idiopathic scoliosis, however, demonstrated greater improvement in SRS-22r than those with adolescent idiopathic scoliosis at final follow-up in pain, function, and total domains.

The minimal clinically important difference was reached in all but the mental domain, for which the minimal clinically important difference has not yet been determined in both adult and adolescent idiopathic scoliosis populations.

Updated on: 09/25/19
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Adolescent Idiopathic Scoliosis, Skeletal Maturity, Surgery—Discussion, Conclusion

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