title: Spinal coronal profiles and proximal femur bone mineral density in adolescent idiopathic scoliosis.
abstract: OBJECTIVE
  Although the occurrence and progression of AIS has been linked to low bone mineral density (BMD), the relationships between spinal curvature and bilateral differences in proximal femur BMD are controversial. Few correlation studies have stratified patients by curve type. The purpose of this study was to evaluate the relationships between spinal coronal profile and bilateral differences in proximal femur BMD in patients with adolescent idiopathic scoliosis (AIS).
  
  
  METHODS
  This study included 67 patients with AIS who underwent posterior correction and fusion surgery between January 2009 and October 2011. The mean age at the time of surgery was 17.4 ± 4.1 years. Bilateral proximal femur BMD was measured before surgery by dual-energy X-ray absorptiometry. We compared the proximal femur BMDs by determining the bilateral BMD ratio (left proximal femur BMD divided by that of the right). We evaluated correlations between coronal parameters, obtained from preoperative radiographs, and the BMD ratio using Pearson's correlation analysis.
  
  
  RESULTS
  Patients with Lenke type 1 curve (48; all with a right convex curve) had a mean bilateral proximal femur BMD ratio of 1.00 ± 0.04. Patients with Lenke type 5 curve (19; all with a left convex curve) had a mean bilateral proximal femur BMD ratio of 0.94 ± 0.04, indicating that the BMD in the proximal femur on the right side (concave) was greater than that in the left (convex). Coronal balance was significantly correlated with the BMD ratio in both the Lenke type 1 and type 5 groups, with a correlation coefficient of 0.46 and 0.50, respectively.
  
  
  CONCLUSIONS
  The bilateral proximal femur BMD ratio was significantly correlated with the coronal balance in AIS patients. When the C7 plumb line was shifted toward one side, the BMD was greater in the contralateral proximal femur.
authors.affiliation: Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan.
authors.forename: Rui-Qiang
authors.initials: RQ
authors.lastname: Chen
authors.forename: Kota
authors.initials: K
authors.lastname: Watanabe
authors.forename: Naobumi
authors.initials: N
authors.lastname: Hosogane
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Hikata
authors.forename: Akio
authors.initials: A
authors.lastname: Iwanami
authors.forename: Ken
authors.initials: K
authors.lastname: Ishii
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D015519:Bone Density; D002648:Child; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000601:surgery; D055815:Young Adult