Open AccessJoint motion in the absence of normal loading does not maintain normal articular cartilage
Author(s) -
Palmoski Marshall J.,
Colyer Robert A.,
Brandt Kenneth D.
Publication year - 1980
Publication title -
arthritis & rheumatism
Language(s) - English
Resource type - Journals
eISSN - 1529-0131
pISSN - 0004-3591
DOI - 10.1002/art.1780230310
Subject(s) - cartilage , knee joint , hyaluronic acid , osteoarthritis , anatomy , proteoglycan , articular cartilage , chemistry , weight bearing , medicine , surgery , pathology , alternative medicine
Articular cartilage from the knees of 4 dogs whose ipsilateral paws had been transected 6 weeks earlier (knee trans ), and from their contralateral knees (knee con ), was examined. Knee trans did not bear weight as a result of the surgical procedure but active motion of the joint, determined with an angular displacement monitor during walking, was comparable to that of knee con . In comparison to knee con cartilage, knee trans samples showed decreases in thickness, Safranin‐O staining of the matrix, and uronic acid content (mean, 24.4%), and increase in water content (mean, 5.9%). Incorporation of 35 S into proteoglycans was 34–67% less in knee trans than in knee con cartilage. Proteoglycan (PG) aggregation in knee con cartilage was normal, whereas in knee trans cartilage the bulk of the proteoglycans, and also those that had been newly synthesized ( 35 S‐proteoglyeans), did not exist in aggregates. This defect in aggregation was due, at least in part, to an abnormality in the hyaluronatebinding region of the core protein of the proteoglycans, since they did not interact in vitro with hyaluronic acid. These changes are essentially identical to those shown to occur in canine knee cartilage after immobilization of the leg in a cast. Thus, the loading of the joint which occurs from contraction of the muscles that span the knee and stabilize the limb in stance, and not merely joint movement, may be required to maintain the integrity of the articular cartilage.