Evaluating methods of restoring cartilaginous articular surfaces.

Surgeons and scientists have developed various approaches to restoring cartilaginous articular surfaces with the intention of relieving pain and improving mobility for people with traumatic or degenerative damage to their synovial joints. These approaches can be divided into two categories: methods intended to stimulate formation of new cartilaginous tissue and transplantation of osteochondral allografts or autografts. Experimental studies have shown that multiple variations of these approaches can restore some form of cartilaginous articular surface, but formation or transplantation of cartilaginous tissue in an animal model does not prove that a given method has the potential to relieve joint symptoms or improve joint function in humans. The effort to restore cartilaginous articular surfaces has reached the point that investigators should now evaluate the experimental results of methods intended to restore cartilaginous articular surfaces in ways that will identify the most promising approaches to the solution of clinical problems. Important issues concerning the experimental models include the types of articular surface defects studied, the age of the animal, and differences in articular cartilage among species. Important considerations in assessing the outcome of procedures designed to restore an articular surface include the overall function of the animal or patient, the function of the joint, the structure of the joint, and the structure, composition, and mechanical properties of the new tissue. This approach to evaluating methods of restoring a cartilaginous articular surface assumes that the goal of any of these methods is to provide sustained improved joint function and decreased joint symptoms in people with traumatic or degenerative joint damage, and that tissues that differ from normal articular cartilage may achieve this goal.