ULTRASTRUCTURAL-CHANGES IN ARTICULAR-CARTILAGE AFTER EXPERIMENTAL SECTION OF THE ANTERIOR CRUCIATE LIGAMENT OF THE DOG KNEE

  • 1 January 1983
    • journal article
    • research article
    • Vol. 136  (MAR) , 425-439
Abstract
The anterior cruciate ligament was sectioned by stab incision of the right knee (stifle) in 16 mature female beagle dogs. The ultrastructure of the area of articular cartilage not covered by the meniscus on the medial tibial condyle was studied at 26 days to 18 mo. after operation. Operated joints were compared with the left control knee and with 6 joints subjected to sham operation, stab incision without ligament section. In the superficial zone of the cartilgae of operated, though not of sham joints, collagen fibrils became abnormally widely spaced from 4 days and a population of narrower fibrils appeared from 7 days, after operation. The matrix beneath the articular surface became infiltrated with unsually large amounts of electron dense amorphous material. Chondrocytes, particularly in the middle zone, became more active with hypertrophy of cytoplasmic organelles observed from 4 days. Superficial cells were initially healthy and their lipid content increased. Evidence of early cell proliferation was followed by cell degeneration several months after operation, when the superficial zone became fissured and cartilage fibrillation became permanent. In sections of control tibial cartilage, intracellular lipid content in the superficial zone was also greater beneath locally fibrillated than beneath locally smooth areas of articular surface.