title: Head and trunk moments of inertia of able-bodied and unbraced scoliotic girls.
abstract: OBJECTIVE
  The purposes of this study were to estimate head and trunk's (HT) radii of gyration (K) and moments of inertia (I) in able-bodied and unbraced scoliotic girls using an angular momentum method, to test if the use of mean ratios calculated in this study and given by de Leva present similar values compared to the experimental data, and to determine how these methods behave in estimation of scoliotic HT's K and I with variable Cobb angles.
  
  
  BACKGROUND
  Scoliotic HT's I estimated from anthropometric tables can lead to error in joint muscle moment calculations.
  
  
  METHODS
  Twenty-one unbraced scoliotic and 20 able-bodied girls participated. HT's I values were calculated using an angular momentum method.
  
  
  RESULTS
  Angular momentum method provided greater HT's I for the scoliotic group compared with the able-bodied girls. HT's I obtained by the mean ratios calculated from this study were close to the measured values. Compared with the experimental I, de Leva method provided significantly lower I in the scoliotic group. Scoliotic HT's K and I obtained from angular momentum method showed greater correlations with the Cobb angles.
  
  
  CONCLUSIONS
  The use of mean ratios obtained in this study to estimate HT's K values in unbraced scoliotic girls could overcome the drawbacks of current anthropometric methods.
  
  
  CONCLUSIONS
  These results can be used to calculate more precise moments of force during daily activities in scoliotic girls with mild scoliosis and to improve the design of corrective flexible body braces prescribed in cases of rapid interventions in young patients of moderate spinal deformities.
authors.affiliation: Hakim Sabzevari University, Sabzevar, Iran mohsen.damavandi1@gmail.com mohsen.damavandi@hotmail.com.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Damavandi
authors.affiliation: University of Montreal, Montreal, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Allard
authors.affiliation: University of Montreal, Montreal, Canada.
authors.forename: Charles-Hilaire
authors.initials: CH
authors.lastname: Rivard
mesh_terms: D000293:Adolescent; D001696:Biomechanical Phenomena / Q000502:physiology*; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006257:Head / Q000502:physiology*; D006801:Humans; D009068:Movement / Q000502:physiology*; D016059:Range of Motion, Articular; D012600:Scoliosis / Q000503:physiopathology*; D060726:Torso / Q000502:physiology*
keywords: adolescent idiopathic scoliosis; biomechanics; head and trunk; moment of inertia; radius of gyration