title: Adolescents with idiopathic scoliosis are not osteoporotic.
abstract: METHODS
  Case controlled study.
  
  
  OBJECTIVE
  To explore the relative effects of body mass index (BMI) and the presence or absence of adolescent idiopathic scoliosis (AIS) on bone mineral density (BMD) as evidenced by Z-scores in adolescents.
  
  
  BACKGROUND
  Prior studies have identified adolescents with idiopathic scoliosis as having "osteoporosis" or "osteopenia," when only a small percentage of subjects in these studies actually had bone density that was clinically abnormal. The terms osteoporosis and osteopenia as used in adults cannot be applied to adolescents and children, as fracture risk has not been well correlated to Z-scores. As we had noted that our scoliosis patients of normal and heavy weight had normal Z-scores, this study was undertaken to explore the relationship of bone mineral density to body mass index in adolescents with and without scoliosis.
  
  
  METHODS
  Dual energy x-ray absorptiometry (DXA) scans of 49 adolescents with adolescent idiopathic scoliosis were compared to 40 normal control adolescents. Z-scores were compared to reduce variability when comparing subjects of varying age and genders. Student t test or simple linear regression was used to explore relationships between Z-scores and clinical and demographic variables.
  
  
  RESULTS
  In both groups of subjects, Z-score was most strongly correlated with BMI (P < 0.001). The presence of scoliosis had the effect of lowering the Z-score as if the individual had "lost" 3.4 BMI units.
  
  
  CONCLUSIONS
  Z-scores in subjects with and without scoliosis were most strongly correlated to BMI: thin patients had lower bone density, heavy patients had higher. The presence of scoliosis had an effect similar to subtracting 3.4 "BMI units," lowering the Z-score from what might otherwise be predicted. The "scoliosis effect" may be noticeable in thin individuals, pushing them to the "low for age" level, whereas in heavier individuals, the effect is negligible. No subjects in either group met the ISCD definition for osteoporosis.
authors: Department of Orthopaedics and Rehabilitation, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA. ESzalay@salud.unm.edu
authors: Elizabeth A
authors: EA
authors: Szalay
authors: Patrick
authors: P
authors: Bosch
authors: Richard M
authors: RM
authors: Schwend
authors: Brian
authors: B
authors: Buggie
authors: Dan
authors: D
authors: Tandberg
authors: Frederick
authors: F
authors: Sherman
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D015992:Body Mass Index; D015519:Bone Density; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D010024:Osteoporosis / Q000150:complications / Q000503:physiopathology; D012307:Risk Factors; D012600:Scoliosis / Q000209:etiology* / Q000503:physiopathology