Cartilage in hemophilic arthropathy. Ultrastructural and microanalytical studies.

The presence of iron in articular cartilage was investigated in five human and two canine cases of factor VIII-deficiency hemophilic arthropathy. The lesions were mild in three cases. Advanced destruction of the cartilage was present in four cases, in one of which sufficient cartilage was preserved to permit recognition of hemosiderin in chondrocytes. The Fe was present in the form of siderosomes and ferritin granules free in the cytoplasm. Iron and phosphorus were demonstrated in the siderosomes by energy dispersion analysis of x-rays; but no Fe was identified by this means or by light or transmission electron microscopy in chondrocytes from the three subjects in an early stage of the disease or in the matrix from any of the seven subjects. The findings lend no support to the hypothesis that salt formation or chelation of Fe ions by matrix proteoglycans is responsible for destruction of cartilage in hemophilic or other chronic hemarthroses. A second, nonferruginous, bilirubin-like pigment (hematoidin) was present in the matrix at the surface of the cartilage in two specimens.