title: Dependence of trabecular structure on bone quantity: a comparison between osteoarthritic and non-pathological bone.
abstract: BACKGROUND
  The mechanical characterization of trabecular bone is related to its structure. In order to describe the trabecular structure and to study the mechanical behavior of the trabecular tissue, several parameters are presented in the literature. Some studies suggest a possible dependence of the structure on bone volume fraction; this dependence could bias the validity of previous studies. The problem increases its complexity when pathological bone such as osteoarthritic tissue is studied, where the organization of the trabecular structure could be different if compared to the non-pathological tissue. The primary aim of this study was to evaluate the dependence between trabecular structure and bone volume fraction. The secondary aim was to compare osteoarthritic and non-pathological bone considering the correlation between structure and bone volume fraction.
  
  
  METHODS
  Sixty trabecular bone specimens were extracted from femoral heads of two groups of 30 Caucasian donors; an osteoarthritic group and a non-pathological group. Several structural parameters, such as bone volume fraction, direct trabecular thickness, fabric tensor eigenvalues and their normalizations, were calculated from micro-CT analysis. A statistical analysis was carried out to identify the dependences between structural parameters and bone volume fraction. The comparison between osteoarthritic bone and non-pathological bone was also performed.
  
  
  RESULTS
  Only the normalized eigenvalues of the fabric tensor were not correlated to bone volume fraction (R<0.5). The first and second normalized eigenvalues were significantly different between osteoarthritic bone and non-pathological bone (respectively P<0.05 and P<0.001).
  
  
  CONCLUSIONS
  In conclusion, orientation and anisotropy of the trabecular structure do not depend on bone volume fraction. Moreover, differences in the first and second normalized fabric tensor eigenvalues suggest in the osteoarthritic group a structure more oriented along the main trabecular direction.
authors.affiliation: Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, Bologna, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Tassani
authors.forename: Francesca
authors.initials: F
authors.lastname: Particelli
authors.forename: Egon
authors.initials: E
authors.lastname: Perilli
authors.forename: Francesco
authors.initials: F
authors.lastname: Traina
authors.forename: Fabio
authors.initials: F
authors.lastname: Baruffaldi
authors.forename: Marco
authors.initials: M
authors.lastname: Viceconti
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D005270:Femur Head / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000473:pathology* / Q000503:physiopathology; D012044:Regression Analysis; D012189:Retrospective Studies; D055114:X-Ray Microtomography / Q000379:methods