title: Biomechanical and immunohistochemical analysis of high hydrostatic pressure-treated Achilles tendons.
abstract: BACKGROUND
  Reconstruction of bone defects caused by malignant tumors is carried out in different ways. At present, tumor-bearing bone segments are devitalized mainly by extracorporeal irradiation or autoclaving, but both methods have substantial disadvantages. In this regard, high hydrostatic pressure (HHP) treatment of the bone is a new, advancing technology that has been used in preclinical testing to inactivate normal cells and tumor cells without altering the biomechanical properties of the bone. The aim of this study was to examine the biomechanical and immunohistochemical properties of tendons after exposure to HHP and to evaluate whether preservation of the bony attachment of tendons and ligaments is possible.
  
  
  METHODS
  For this, 19 paired Achilles tendons were harvested from both hindlimbs of 4-month-old pigs. After preparation, the cross-sectional area of each tendon was determined by magnetic resonance imaging (MRI). For each animal, one of the two tendons was taken at random and exposed to a pressure of 300 MPa (n = 9) or 600 MPa (n = 10).
  
  
  RESULTS
  The contralateral tendon served as an untreated control. The biomechanical properties of the tendons remained unchanged with respect to the tested parameters: Young's modulus (MPa) and tensile strength (MPa). This finding is in line with immunohistochemical labeling results, as no difference in the labeling pattern of collagen I and versican was observed when comparing the HHP group (at 600 MPa) to the untreated control group.
  
  
  CONCLUSIONS
  We anticipate that during orthopedic surgery HHP can serve as a novel, promising methodical approach to inactivate Achilles tendon and bone cells without altering the biomechanical properties of the tendons. This should allow one to preserve the attachment of tendon and ligaments to the devitalized bone and to facilitate functional reconstruction.
authors.affiliation: Department of Orthopedic Surgery, Technical University of Munich, Ismaninger Str. 22, D-81675 Munich, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Diehl
authors.forename: Erwin
authors.initials: E
authors.lastname: Steinhauser
authors.forename: Hans
authors.initials: H
authors.lastname: Gollwitzer
authors.forename: Cornelia
authors.initials: C
authors.lastname: Heister
authors.forename: Johannes
authors.initials: J
authors.lastname: Schauwecker
authors.forename: Stefan
authors.initials: S
authors.lastname: Milz
authors.forename: Wolfram
authors.initials: W
authors.lastname: Mittelmeier
authors.forename: Manfred
authors.initials: M
authors.lastname: Schmitt
mesh_terms: D000125:Achilles Tendon / Q000378:metabolism / Q000502:physiology; D000818:Animals; D001696:Biomechanical Phenomena; D024042:Collagen Type I / Q000378:metabolism; D006614:Hindlimb; D006874:Hydrostatic Pressure; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D019651:Plastic Surgery Procedures; D013552:Swine; D013718:Tensile Strength; D053675:Versicans / Q000378:metabolism
chemical_list: D024042:Collagen Type I; D053675:Versicans