title: Ultimate stress and age-dependent deformation characteristics of the iliotibial tract.
abstract: OBJECTIVE
  To understand biomechanics of ligaments and tendons data on their material properties are necessary. The iliotibial tract is a suitable model for virtual pelvic or lower extremity ligaments due to its parallel fibers, which facilitates biomechanical testing. Here, we determined Young's modulus (YM) as secant stiffness between defined limits of the iliotibial tract and correlated the data to ultimate stress (US) of the specimens and to age, gender and body weight of the body donors.
  
  
  METHODS
  Thirty eight specimens from 12 iliotibial tracts of 10 young donors (mean age 31.2±9.1 years) were investigated biomechanically. After preconditioning, YM were determined in the ranges of 0-4 and 4-11 N/mm² of applied stress and from 4N/mm² of applied stress to US.
  
  
  RESULTS
  YM of the specimens were 84.7±30.2 (0-4 N/mm²), 335.4±101.9 (4-11 N/mm²), and 369.1±191.5 (4 N/mm² to US) N/mm², respectively. The mean US was 35.8±16.4 N/mm². YM and US correlated closely in the ranges of 4-11 N/mm² (r=0.95) and 4 N/mm² to US (r=0.91). YM did not correlate to age, body weight or gender within these young donors. Concerning tissue behavior a decrease of YM, i.e. weakening, is more common than an increase of YM, i.e. stiffening, before specimen failure. Overall, YM of specimens from young donors were significantly lower compared to those of old donors.
  
  
  CONCLUSIONS
  This is the first study providing age-dependent nonlinear stiffness properties of the iliotibial tract. YM is significantly lower in young than in old donors and is thus a subject of alteration during life time.
authors.affiliation: Institute of Anatomy, University of Leipzig, Faculty of Medicine, Leipzig, Germany. niels.hammer@medizin.uni-leipzig.de
authors.forename: Niels
authors.initials: N
authors.lastname: Hammer
authors.forename: Uwe
authors.initials: U
authors.lastname: Lingslebe
authors.forename: Gabriela
authors.initials: G
authors.lastname: Aust
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Milani
authors.forename: Carsten
authors.initials: C
authors.lastname: Hädrich
authors.forename: Hanno
authors.initials: H
authors.lastname: Steinke
mesh_terms: D000328:Adult; D000375:Aging; D001696:Biomechanical Phenomena; D003238:Connective Tissue / Q000502:physiology*; D055119:Elastic Modulus / Q000502:physiology; D005206:Fascia Lata / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D013314:Stress, Mechanical; D055815:Young Adult