SPONTANEOUS OSTEOARTHRITIS IN HARTLEY,DUNKIN GUINEA-PIGS - HISTOLOGIC, RADIOLOGIC, AND BIOCHEMICAL-CHANGES

Dunkin Hartley guinea pigs develop spontaneous, age-related osteoarthr itis (OA) of the knee and other joints, Histologic changes are observe d beginning at 3 months of age, Disease severity increases with age, a nd at 18 months moderate to severe OA is observed. A study was underta ken to assess the morphologic and biochemical changes of 22-month-old animals, and to compare them with values in a-month-old guinea pigs. B iochemical indices characteristic of OA, from tibial cartilage, indica ted an increase in proteoglycan content from 233 +/- 2 mu g/mg (mean /- SEM) at 2 months of age to 365 +/- 6 mu g/mg at 22 months. Collagen concentration in cartilage decreased from 364 +/- 2 mu g/mg at 2 mont hs to 223 +/- 3 mu g/mg at 22 months. Proteoglycan fragments found in synovial fluid measured 4.6 +/- 1 mu g/ml at 2 months and increased to 37 +/- 2 mu g/ml at 22 months. Radiographic changes observed at 22 mo nths included marginal osteophytes of the tibia and femur, sclerosis o f the subchondral bone of the tibial plateau, femoral condyle cysts, a nd calcification of the collateral ligaments, Histologic evaluation re vealed severe OA, with a Mankin score of 10.7 +/- 0.5 in 22-month-old animals. In contrast, 2-month-old animals had no histologic or radiogr aphically detectable lesions. The results of the study reported here i ndicate that the lesions observed in this model are similar to those o f human OA. Spontaneous development of OA in guinea pigs is amenable t o the study of the pathogenesis of OA and to the evaluation of potenti al disease-modifying agents.