title: Experimental articular cartilage repair in the Göttingen minipig: the influence of multiple defects per knee.
abstract: BACKGROUND
  A gold standard treatment for articular cartilage injuries is yet to be found, and a cost-effective and predictable large animal model is needed to bridge the gap between in vitro studies and clinical studies. Ideally, the animal model should allow for testing of clinically relevant treatments and the biological response should be reproducible and comparable to humans. This allows for a reliable translation of results to clinical studies.This study aimed at verifying the Göttingen minipig as a pre-clinical model for articular cartilage repair by testing existing clinical cartilage repair techniques and evaluating the use of two defects per knee.
  
  
  METHODS
  Sixteen fully mature Göttingen minipigs were used. The minipigs received bilateral trochlear osteochondral drill-hole defects or chondral defects (Ø 6 mm), either one defect per knee or two defects per knee. The defects were treated with one of the following: Matrix-induced autologous chondrocyte implantation (MACI), microfracture (MFx), autologous-dual-tissue transplantation (ADTT), autologous bone graft, autologous cartilage chips. Empty chondral and osteochondral defects were used as controls. MRI and CT were performed 3 and 6 month, histology was performed 6 month postoperative.
  
  
  RESULTS
  The repair tissue varied in morphology from non-cartilaginous fibrous tissue to fibrocartilaginous tissue as seen on MRI, CT and histology at 6 month. The worst results were seen in the empty controls, while the best results were achieved with the MACI and ADTT treatment. The use of two defects per knee did not have any significant effect on the repair response.
  
  
  CONCLUSIONS
  The outcomes of the applied treatments were consistent with the outcomes in clinical studies and it was possible to apply two defects per knee. The Göttingen minipig model was easy to handle, cost-effective and provided predictable outcome. Based on this study the use of two defects per knee, one in the medial and one in the lateral trochlear facet, in male Göttingen minipigs is recommended.
authors.affiliation: Orthopedic Research Laboratory, Aarhus University Hospital, Nørrebrogade 44, building 1A, 1. Floor, Aarhus, Denmark. bjornbc@gmail.com.
authors.forename: Bjørn Borsøe
authors.initials: BB
authors.lastname: Christensen
authors.affiliation: Orthopedic Research Laboratory, Aarhus University Hospital, Nørrebrogade 44, building 1A, 1. Floor, Aarhus, Denmark. foldager@clin.au.dk.
authors.forename: Casper Bindzus
authors.initials: CB
authors.lastname: Foldager
authors.affiliation: Orthopedic Research Laboratory, Aarhus University Hospital, Nørrebrogade 44, building 1A, 1. Floor, Aarhus, Denmark. mlol@clin.au.dk.
authors.forename: Morten Lykke
authors.initials: ML
authors.lastname: Olesen
authors.affiliation: Orthopedic Research Laboratory, Aarhus University Hospital, Nørrebrogade 44, building 1A, 1. Floor, Aarhus, Denmark. louise_vingtoft@hotmail.com.
authors.forename: Louise
authors.initials: L
authors.lastname: Vingtoft
authors.affiliation: Orthopedic Research Laboratory, Aarhus University Hospital, Nørrebrogade 44, building 1A, 1. Floor, Aarhus, Denmark. jan.roelfing@clin.au.dk.
authors.forename: Jan Hendrik Duedal
authors.initials: JH
authors.lastname: Rölfing
authors.affiliation: MR Research Center, Aarhus University Hospital, Skejby, Denmark. steffen@clin.au.dk.
authors.forename: Steffen
authors.initials: S
authors.lastname: Ringgaard
authors.affiliation: Department of Sports Traumatology, Department of orthopedic surgery, Aarhus University Hospital, Aarhus, Denmark. martilin@rm.dk.
authors.forename: Martin
authors.initials: M
authors.lastname: Lind
keywords: Animal model; Articular cartilage; Bone graft; Cartilage chips; Göttingen minipig