The canine ‘groove’ model of osteoarthritis is more than simply the expression of surgically applied damage

SummaryObjectiveRecently 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.MethodsIn 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 4h/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.ResultsTen 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