Evolutional patterns of articular cartilage following growth plate injury in rats

Background. No study to date has analyzed the damage of the articular cartilage and its relation to growth plate injury. The purpose of this study was to test whether primary injury to the growth plate contributes to secondary damage to the articular cartilage in rats. Methods. A total of 109 two-week-old male Wistar rats were allocated to four lesional groups. In group I (controls) no surgery took place. In the remaining animals, an injury was caused in the proximal physis of the left tibia: group II, perichondrial ring injury; group III, direct injury to the growth plate; group IV, traumatic separation of the epiphysis where a Salter-Harris II-type injury was created. The results were assessed at 1 week, 6 weeks, and 6 months. A growth plate score was used. The stereological and histological changes in the articular cartilage were analyzed, and the results were subjected to statistical analysis. Results. Histological studies showed discrete degenerative changes in the articular cartilage in the injured growth plate. Changes in the cell density, mean cell volume, and articular cartilage occurred in the injured growth plate. The changes appeared to be transient in groups II and III. Conclusions. Primary injury to the growth plate contributes to secondary damage to the articular cartilage in young rats. Our data - extrapolated to the clinical view - suggests that a Salter-Harris type II injury does not seem to have impunity to subsequent joint degeneration.