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Critical Reviews™ in Biomedical Engineering

ISSN Print: 0278-940X
ISSN Online: 1943-619X

Critical Reviews™ in Biomedical Engineering

DOI: 10.1615/CritRevBiomedEng.v29.i4.10
pages 373-391

Relationship Among Biomechanical, Biochemical, and Cellular Changes Associated with Osteoarthritis

Frederick H. Silver
Department of Pathology and Laboratory Medicine, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854
Gino Bradica
Departments of Pathology and Laboratory Medicine and Surgery, UMDNJ-Robert Wood Johnson Medical School, Piscataway, NJ 08854
Alfred Tria
Rutgers Medical School

ABSTRACT

Articular cartilage that lines the surface of long bones is a multilayered material. The superficial layer consists of collagen fibrils and chondrocytes that run parallel to the joint surface. In the deeper layers, the collagen fibrils are more randomly arranged and support vertical units termed chondrons containing rows of chondrocytes. In the deepest layers, the collagen fibrils run almost vertically and ultimately insert into the underlying subchondral bone.
Osteoarthritis (OA) is a disease that affects articular cartilage and is characterized by enzymatic and mechanical breakdown of the extracellular matrix, leading to cartilage degeneration, exposure of subchondral bone, pain, and limited joint motion. Changes in mechanical properties of articular car-tilage associated with OA include decreases in modulus and ultimate tensile strength. These changes parallel the changes observed after enzymatic degradation of either collagen or proteoglycans in car-tilage. Results of recent viscoelastic studies on articular cartilage suggest that the elastic modulus of collagen and fibril lengths decrease in OA and are associated with a loss of the superficial zone and a decreased ability of articular cartilage to store elastic energy during locomotion. It is suggested that osteoarthritic changes to cartilage involve enzymatic degradation of matrix components and fibril fragmentation that is promoted by subsequent mechanical loading.