Rh. Ostendorf et al., CYCLIC LOADING IS HARMFUL TO ARTICULAR-CARTILAGE FROM WHICH PROTEOGLYCANS HAVE BEEN PARTIALLY DEPLETED BY RETINOIC ACID, Osteoarthritis and cartilage, 3(4), 1995, pp. 275-284
We studied whether cyclic loading is harmful to degraded cartilage. Se
ts of four cartilage-bearing sesamoid bones were dissected from 5-year
-old cows. One bone from each set was cultured for 17 h in control med
ium to serve as an ex vivo control. The three others were cultured for
1 week in control medium to which 0, 10 or 300 ng/ml retinoic acid (R
Ac), which depletes the cartilage matrix of proteoglycans, had been ad
ded, Two were then cultured for another week in control medium. During
the last week, one of the two was subjected to a cyclic load (1 MPa,
0.2 Hz). Following treatment with RAc, glycosaminoglycan content and s
ynthesis were significantly decreased, as confirmed by safranin 0 stai
ning and autoradiography. They were further diminished by loading duri
ng the second week of culture. Increased amounts of 3-B-3(-) epitope w
ere found in cartilage that had been treated with 300 ng/ml RAc and th
en loaded. While loading cartilage matrix that was only slightly degra
ded proved to be damaging, loading severely degraded cartilage matrix
apparently induced osteoarthritic-like changes.