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PART II: DEGENERATION AND OSTEOARTHROSIS, REPAIR, REGENERATION, AND TRANSPLANTATION*t BY J. A. BUCKWALTER, M.D.tt, IOWA CITY, IOWA, AND H. J. MANKIN, M.D., BOSTON, MASSACHUSETTS
Joint pain and loss of mobility are among the most common causes of impairment in middle-aged and older people36,134. In many instances, the degeneration of articular cartilage and alterations in other joint tissues that result from the loss of structure and function of articular cartilage cause the pain and the loss of motion28,46,47,85,118,150. This occurs most frequently in the clinical syndrome of idiopathic or primary osteoarthrosis, but it may also result from joint injury or from developmental, metabolic, and inflammatory disorders that destroy the articular surface, causing secondary osteoarthrosis28,46,118. An understanding of the degeneration of articular cartilage, osteoarthrosis, and the potential for restoring an articular surface depends to a large extent on an appreciation of the biological behavior and the responsiveness of articular cartilage to injury and disease. Of considerable importance is the observation, first reported centuries ago and confirmed by multiple investigators over the last fifty years, that adult articular cartilage does not have the capacity to repair structural damage resulting from injury or disease29,32,71. This observation has contributed to the view that adult articular cartilage is an inert bearing surface, like high-density polyethylene or metal, and that degeneration of the articular surface with age is the result of mechanical wear with inevitable, irreversible loss of structure and mechanical performance resulting from joint use62. The implication of this view is that, other than limiting joint use or loading, little or nothing can be done to prevent the degeneration of articular cartilage, and the most appropriate treatment for advanced degeneration of cartilage leading to the clinical syndrome of osteoarthrosis is replacement of the articular surface. Alternatively, if articular cartilage is not inert, in particular if it has the capacity to restore and remodel itself, then mechanical wear from joint use may not cause degeneration and osteoarthrosis, and therapeutic approaches aimed at maintaining or restoring articular cartilage are appropriate for at least some patients. A determination of which view is correct is critical for developing and implementing methods of preventing and treating osteoarthrosis.
This review covers the current understanding of the degeneration of articular cartilage (the alterations in composition and the...