OSTEOARTHROSIS IN GUINEA-PIGS - HISTOPATHOLOGIC AND SCANNING ELECTRON-MICROSCOPIC FEATURES

  • 1 March 1989
    • journal article
    • research article
    • Vol. 39  (2) , 115-121
Abstract
Spontaneous cartilage degeneration of the femorotibial joint of male Hartley guinea pigs, 61 to 365 days old, was studied by light microscopy (LM) and scanning electron microscopy (SEM) to determine the incidence, age at onset, and to characterize the early changes. Knee joints of 61 day old animals were histologically and ultrastructurally normal. Focal minimal degeneration characterized by cell and proteoglycan loss with surface fibrillation was first observed by LM on the medial tibial plateau (MTP) in two of five 89 day old animals. Mild lesions characterized by focal surface disruption, primarily in the area of media tibial plateau not covered by the meniscus, were observed in three of five 89 day old animals by SEM. Light microscopic alterations in knee joints of 4, 5 and 6 month old animals consisted of varying degrees of focal chondrocyte death, decreased toluidine blue matrix staining, and surface fibrillation. SMall chondrocytic clones were first observed in medial tibial cartilage of 6 month old animals with moderate focal degeneration. Ultrastructurally, 4, 5, and 6 month old animals generally had moderate to severe fibrillation involving primarily the area of the medial tibial plateau not covered by the meniscus. Tibial osteophyte formation, mild synovial hyperplasia, medial femoral and meniscal cartilage degeneration, were first seen by LM in 9 month old animals. Lesions in 1 year old animals were similar, but more severe and included subchondral sclerosis of medial tibial and femoral bone. Bilateral fibrillation of greater than 50% of the medial tibial articular surface was observed in all 1 year old animals by SEM. Minimal cartilage degeneration was evident in the shoulder and elbow joints of a few 1 year old guinea pigs. Degeneration of the femorotibial joint is a common lesion in relatively young guinea pigs. The early lesions of focal chondrocyte death and matrix degeneration become progressively more severe with age, and lesions in some 9 and 12 months old animals resemble those present in humans with osteoarthritis. The guinea pig may, therefore, be a useful animal model in which to study the early biochemical and cellular changes associated with spontaneous cartilage degeneration.