CHANGES INDUCED BY SUSTAINED PRESSURE IN THE KNEE JOINT ARTICULAR CARTILAGE OF ADULT RABBITS.

Abstract

AbstractThe right knees of rabbits were rigidly fixed with metal clamps midway between full flexion and full extension. After six dayas the knees of six were preserved while clamped. Twenty other rabbits were sacrificed after 16 days. Ten received colchicine on the eighth, eleventh and fifteenth day following clamp application. Their knees were preserved after clamp removal. The femoral and tibial articular cartilages subjected to pressure for six days were extremely compressed but viable. In knees clamped for 16 days the changes found were related to the amount of knee movement present at autopsy. Where it was small but easily detectable the cartilages were normal. Where there was no movement the cartilage was dead. Where it was only slight variable cartilage changes were found ranging from surface abradement, Matrix swelling, enlargement of lacunae and chondrocytes, increased number of cells per lacuna, and an occasional chondrocyte in mitosis, to an extensive matrix alteration resulting in the disappearance of lacunae, chondrocytes released from the confines of lacunae and interspersed among a meshwork of fine collagen fibers, and a few released chondrocytes in mitosis. The most extensive change was where the cartilage defect area was occupied by a mass of proliferating richly‐cellular tissue. The knee articular cartilage changes of this experiment are compared with those occurring during pregnancy in the pubic symphyseal cartilage of mice.