title: The canine 'groove' model of osteoarthritis is more than simply the expression of surgically applied damage.
abstract: OBJECTIVE
  Recently a new canine model of osteoarthritis (OA; the 'groove' model) has been described. This model is based on surgically applied mechanical damage of the articular cartilage followed by transient forced loading of the affected joint. Ten weeks after surgery this model shows characteristics of OA, mimicking human OA. To establish whether the observed characteristics of degeneration in this model represent the surgically applied damage, or are the results of progressive features of OA, we evaluated this 'groove' model shortly after surgery.
  
  
  METHODS
  In 20 female Beagle dogs, articular cartilage of the weight-bearing areas of the femoral condyles in the right knee was damaged without affecting the underlying bone. After surgery dogs were let out on a patio 5 days/week for 4 h/day. The dogs were forced to load the experimental joint by fixing the contralateral control limb to the trunk 3 days/week. The severity of OA was evaluated at 3 (n = 10) or 10 weeks (n = 10) after surgery. Synovial inflammation, cartilage damage and cartilage matrix turnover were determined.
  
  
  RESULTS
  Ten weeks after surgery osteoarthritic features were found, as described previously. Proteoglycan (PG) synthesis, percentage release of newly formed PG, and that of total amount of PG were enhanced, whereas PG content was significantly diminished (all P < 0.05). Importantly, 3 weeks after surgery these characteristics of OA were not yet evident.
  
  
  CONCLUSIONS
  The present results clearly show that the characteristics observed 10 weeks after induction of joint degeneration in the groove model are not just the expression of the surgically applied damage but are the result of progressive features of (experimental) OA.
authors.affiliation: Rheumatology & Clinical Immunology, University Medical Center Utrecht, The Netherlands. s.mastbergen@azu.nl
authors.forename: Simon C
authors.initials: SC
authors.lastname: Mastbergen
authors.forename: Anne C
authors.initials: AC
authors.lastname: Marijnissen
authors.forename: Marieke E
authors.initials: ME
authors.lastname: Vianen
authors.forename: Peter M
authors.initials: PM
authors.lastname: van Roermund
authors.forename: Johannes W
authors.initials: JW
authors.lastname: Bijlsma
authors.forename: Floris P
authors.initials: FP
authors.lastname: Lafeber
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D005269:Femur; D006614:Hindlimb; D010003:Osteoarthritis / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D011509:Proteoglycans / Q000378:metabolism; D013583:Synovial Membrane / Q000473:pathology; D013977:Tibia
chemical_list: D011509:Proteoglycans