title: Mechanical properties of intrasynovial and extrasynovial tendon fascicles.
abstract: BACKGROUND
  Tendon grafting in tendon reconstruction often involves the interchange of intrasynovial and extrasynovial tendons. Although many studies have examined the cellular and biological differences between tendons of various sources, few have studied the mechanical properties of these two different types of tendons. The purpose of this study was to investigate the mechanical properties of intrasynovial and extrasynovial tendons.
  
  
  METHODS
  Canine peroneus longus (extrasynovial) and flexor digitorum profundus (intrasynovial) tendons, further subdivided into intrasynovial tendinous and intrasynovial fibrocartilaginous segments, were used in the study. An indentation test was used to measure the compressive modulus. Tensile testing was performed on 400mum longitudinal sections.
  
  
  RESULTS
  The compressive modulus of the intrasynovial fibrocartilaginous segment was significantly higher than that of the intrasynovial tendinous segment, which was in turn significantly higher than that of the extrasynovial tendon (P<0.0001). The tensile modulus of extrasynovial tendon was significantly higher than that of intrasynovial fibrocartilaginous and intrasynovial tendinous segments (P<0.005). The tensile modulus of the intrasynovial fibrocartilaginous and tendinous segments was not significantly different (P=0.14).
  
  
  CONCLUSIONS
  The results suggest that extrasynovial tendons exhibit superior tensile properties but inferior compressive properties when compared to intrasynovial tendons, which is consistent with their biological role in situ, but which could lead to complications when these tendons are repositioned during tendon graft surgery.
authors.affiliation: Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Shin
authors.forename: Chunfeng
authors.initials: C
authors.lastname: Zhao
authors.forename: Mark E
authors.initials: ME
authors.lastname: Zobitz
authors.forename: Peter C
authors.initials: PC
authors.lastname: Amadio
authors.forename: Kai-Nan
authors.initials: KN
authors.lastname: An
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D019245:Compressive Strength; D004285:Dogs; D006614:Hindlimb; D016059:Range of Motion, Articular / Q000502:physiology; D013583:Synovial Membrane / Q000502:physiology*; D013710:Tendons / Q000502:physiology* / Q000637:transplantation*; D013718:Tensile Strength