Paper# III-1

SAGITTAL PELVIC MORPHOLOGY IN NORMAL ADOLESCENTS AND PATIENTS WITH ADOLESCENT IDIOPATHIC SCOLIOSIS

Jean-Marc Mac-Thiong, MD

Montreal, QC

Co-Authors

J.A. de Guise

H. Labelle

Recent studies (Cheung et al., 2003; Ylikoski et al., 2003) have shown that adolescent idiopathic scoliosis (AIS) was associated with abnormal peripubertal growth. Nicolopoulos et al. (1985) suggest that there may be abnormal pelvic geometry in AIS. This study compares the sagittal pelvic morphology between normal adolescents and patients with AIS.

The sacral slope, pelvic tilt and pelvic incidence were assessed on the lateral standing radiograph of 145 normal subjects and 160 patients with AIS (mean coronal Cobb angle: 43 ± 15°).

The mean sacral slope, pelvic tilt and pelvic incidence were respectively 41.4 ± 7.5°, 7.9 ± 7.7° and 49.3 ± 11.2° in the normal group. Corresponding values for AIS patients were 47.8 ± 9.3°, 9.5 ± 8.7° and 57.3 ± 13.8°, respectively. There was a significant difference in sacral slope and in pelvic incidence between the two groups (p < 10^-7).

The sacral slope and the pelvic incidence were significantly higher in patients with AIS. Since the pelvic incidence tends to increase during growth, it is possible that the difference in pelvic morphology is associated with the abnormal peripubertal growth seen in AIS.