Biochemical changes in the articular cartilage of the patella and femoral condyles in the lateral hyperpatellar syndrome.

The biochemical changes in the articular cartilage of the femoral condyles and the patella were studied during the earliest stage of patello-femoral arthrosis, with particular reference to chondromalacia of the patella in the "lateral hypertension syndrome", with the object of comparing them with the results obtained by Boni et al. (1977) in the initial phases of experimental arthrosis induced in rabbits by means of vitamin A. The biochemical determinations were done on samples of cartilage removed at operation from the medial and lateral femoral condyles and the medial and lateral patellar articular facets in ten patients. The biopsy samples were fixed in 80% alcohol and dried in the oven at 50 degrees C for twenty-four hours. The hexosamine and hydroxyproline content was then determined. This investigation demonstrated significant biochemical changes in this syndrome in the four areas examined. The data obtained indicate that only the mucopolysaccharide component of the joint cartilage is involved at this stage. The most interesting finding was marked diminution in the galactosamine/glucosamine ratio, which was markedly diminished - the opposite of what occurs in established arthrosis. These data appear to be identical with those found in the early phases of vitamin A induced arthrosis in experimental rabbits. The diminution of hexosamine content and the diminished galactosamine/glucosamine ratio were more marked in the femoral condyles, which appeared to have few lesions macroscopically. These changes were also present in both articular facets of patella, but were less marked, probably because the degeneration was more advanced in those areas, thus more closely resembling frank arthrosis.