title: The influence of locally applied platelet-derived growth factor-BB on free tendon graft remodeling after anterior cruciate ligament reconstruction.
abstract: BACKGROUND
  Ligaments and tendons do not gain mechanical properties of the native tissue after injury or grafting.
  
  
  OBJECTIVE
  To determine the influence of platelet-derived growth factor on tendon graft remodeling.
  
  
  METHODS
  Laboratory animal study.
  
  
  METHODS
  Forty-eight sheep underwent anterior cruciate ligament reconstruction and were sacrificed after 3, 6, 12, and 24 weeks. In 6 animals at each time point, platelet-derived growth factor was locally delivered via coated sutures. After mechanical testing, tissue samples were taken for histologic, immunohistochemical, and electron microscopy evaluations.
  
  
  RESULTS
  With platelet-derived growth factor treatment, cross-sectional area was significantly lower at 3 and 12 weeks. Load to failure was significantly higher at 6 weeks. Tensile stress was significantly higher at 3 and 12 weeks. Crimp length was significantly higher at 3 and 6 weeks. Vascular density was significantly higher at 6 weeks. Electron microscopy showed a significantly higher collagen fibril amount at 12 weeks. Differences in these parameters at other time points were not significant.
  
  
  CONCLUSIONS
  There were alterations in several but not all time points. The local application of platelet-derived growth factor alters the tissue's mechanical properties during free tendon graft remodeling after anterior cruciate ligament reconstruction. Growth factors present a promising tool toward the complete mechanical restitution of a healing ligament substitute.
authors.affiliation: Sports Traumatology & Arthroscopy Service, Trauma & Reconstructive Surgery, Charité, Humboldt-University of Berlin, Augustenburger Platz 1, 13353 Berlin, Germany. andreas.weiler@charite.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Weiler
authors.forename: Cornelius
authors.initials: C
authors.lastname: Förster
authors.forename: Patrick
authors.initials: P
authors.lastname: Hunt
authors.forename: Roman
authors.initials: R
authors.lastname: Falk
authors.forename: Tobias
authors.initials: T
authors.lastname: Jung
authors.forename: Frank N
authors.initials: FN
authors.lastname: Unterhauser
authors.forename: Volker
authors.initials: V
authors.lastname: Bergmann
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schmidmaier
authors.forename: Norbert P
authors.initials: NP
authors.lastname: Haas
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D016503:Drug Delivery Systems; D005260:Female; D010982:Platelet-Derived Growth Factor / Q000008:administration & dosage*; D020033:Protein Isoforms; D012756:Sheep; D013314:Stress, Mechanical; D013537:Sutures; D013710:Tendons / Q000098:blood supply / Q000637:transplantation* / Q000648:ultrastructure; D013718:Tensile Strength
chemical_list: D010982:Platelet-Derived Growth Factor; D020033:Protein Isoforms