Exuberant articular cartilage response to osteoarthritis infemoral heads

IntroductionOsteoarthritis is an important cause of disability and dysfunction in the community.The incidence of osteoarthritis is rising with increasing obesity prevalence andlongevity. Osteoarthritis is a degenerative joint disease with articular cartilageloss and reactive bone changes. Some cartilage regeneration with cartilage cellproliferation and cartilage matrix production do occur.AimTo present a case of osteoarthritis with profound chondroid proliferation anddiscuss the possible reasons for this unusual reaction are discussed.Materials and methodsA 49 year old obese man decreased sensation on the left side correspondingto the L4 to S1 dermatomes after sustaining a low back injury while swimming.Investigations revealed osteoarthritis in his hip joints. He underwent bilateral totalhip replacement during a 12 month period.ResultsThe femoral heads were very irregular with a polypoid appearance due to areasof florid cartilage proliferation with some ossification. The new cartilage hadgrown over damaged cartilage and bone. Features of usual osteoarthritis withfrayed and fragmented cartilage, bone sclerosis and subchondral cyst formationwere also seen.ConclusionExuberant chondrocyte proliferation and pronounced new cartilage formation,as seen in this case, are rarely observed in surgically removed specimens. Thisproliferative articular cartilage change in this patient is likely to represent an attemptat repair. The reason for these proliferation changes is unclear but according tothe literature an imbalance between the catabolic and anabolic growth factors andcytokines may account for the changes.