Approval of this retrospective study was obtained from the Second Central Hospital of Baoding. The medical records of eligible patients with AIS who underwent Chêneau bracing between January 2018 and August 2019 in our department were reviewed retrospectively. We excluded patients with congenital scoliosis, syndromic scoliosis, structural leg discrepancies, and patients aged 16 or more at the time of bracing.
Inclusion criteria for the indication of brace were: Lenke5 AIS,skeletal immaturity, premenarcheal or postmenarcheal by less than 1 year, a CA between 15° and 45°. receiving Chêneau brace (Figure 1); having ongoing bracing treatment for at least six months prior to study.
Radiographic assessment
Standing whole spine radiographs were ensured that patients were completely erect and their pelvis was not rotated. Radiological parameters were measured from anteroposterior and lateral standing radiographs of whole spinal, which were obtained pro-bracingly and in-bracingly. All of the measurements were performed by Surgimap Spine Software(New York, USA). Measurements were all conducted by two investigators independently and blinded to the clinical information to avoid bias. The list of patients for measurement were randomly allocated and provided by another investigator. An average score was used for any measurement with < 5 degrees of difference. Any difference beyond 5 degrees was discussed between the investigators with a final consensus on the measurement used for analysis. The cutoff of 5 degrees was used based on documented radiographic measurement errors in a scoliotic curve.
The spinopelvic parameters of pro-bracing and in-bracing radiographs were used to assess:
CA defined as the angle between the perpendicular lines from the upper endplate of the most tilted superior vertebra and lower endplate of the most tilted inferior vertebra.
PCOA defined as the angle between a line connecting the top of both iliac crests and the horizontal line was measured on standing AP radiographs.
TLK defined as the angle between the upper endplate of the T10 vertebra and lower endplate of the L2 vertebra
LL: The angle between the superior end plate of L1 and the superior end plate of S1.
PI: The angle between the line perpendicular to the sacral plate at its midpoint and the line connecting this point to the axis of the femoral heads.
PT: The angle between the line connecting the midpoint of the sacral plate to the femoral head axis and the vertical axis.
SS: The angle between the superior plate of S1 and a horizontal line. The lower arc of LL is geometrically equal to the sacral slope (SS).
SVA: The sagittal angle between the line from the center of the C7 vertebral body to the center of the upper sacral endplate and vertical line.
CVA: The coronal angle between the line from the center of the C7 vertebral body to the center of the upper sacral endplate and vertical line.
The pro-bracing and in-bracing radiographs of the patients were used to assess these parameters.
Statistical Analysis
The data was analyzed using SPSS Statistics 25 (IBM Corp, Armonk, NewYork, USA) Shapiro-Wilk test found that the data was normally distributed. Paired t-test was used to compare pro-bracing and in-bracing spinopelvic parameters. The Pearson correlation analysis was used to identify the relationships between the variations in the spinopelvic parameters. P < 0.05 was considered statistically significant.