Cyclic loading can denature type II collagen in articular cartilage.
We sought to explain previously reported associations between osteoarthritis, cartilage collagen denaturation, and repetitive mechanical loading. Eighty specimens of cartilage-on-bone were obtained from bovine patella grooves. After soaking in protease inhibitors, specimens were subjected to 3,600 cycles of compressive loading by means of a flat indenter. Loaded cartilage was supported by adjacent cartilage and subchondral bone. Peak stress ranged between 3.5 MPa and 14 MPa. Collagen denaturation was assessed by an inhibition ELISA assay using the col2-3/4 m antibody. Results showed that denaturation increased with loading severity, from 2% in control (unloaded) cartilage to 7.5% at 14 MPa (p < .0003). Collagen and glycosaminoglycan content of cartilage were unchanged after loading. Denaturation was largely unaffected by the absence of protease inhibitors or when chondrocytes were killed by repeated freeze-thaw cycles prior to loading. We conclude that vigorous cyclic mechanical loading causes an immediate dose-related increase in collagen denaturation in bovine articular cartilage.
Clements
Kristen M
KM
Department of Anatomy, University of Bristol, UK.
Hollander
Anthony P
AP
Sharif
Mohammed
M
Adams
Michael A
MA
D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism*; D002417:Cattle; D024043:Collagen Type II / Q000737:chemistry* / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D011489:Protein Denaturation / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology*
D024043:Collagen Type II