A study of 260 cases of skeletal fluorosis demonstrated that the large joints of the extremities were severely damaged, especially the elbow, which was involved in 93% of the cases. In order to dctermine whether fluorosis damages cartilage, 20 young rabbits, and 10 young dogs were fed with sodium fluoride 20 mglkg/day for periods up to 6 months. Radiographs and correlated HE-stained sections of the large joints of the extremities were made. Electromicroscopic examinations were also made of cartilage specimens of 5 young dogs.
Histologic study showed irregular calcareous deposits and globules in the matrix of the articular and epiphyseal cartilage. In the epiphyseal cartilage the way these were concentrated demonstrated that the disturbance occurred in the course of epiphyseal cartilage calcification. We also saw multiple dry necroses in the anicular cartilage.
Electromicroscopic cxamination showed chondrocyte deformations, with cellular processes shortened or disappeared, calcareous deposits within the cytoplasm, increased glycogen deposition which almost filled the cell body, with
organelles disappeared and myelin appearing in the cell. All the above changes indicate necrosis of the cell, demonstrating the direct damage to chondrocytes which is the origin of the damage to cartilage caused by fluorosis. We suggest that this pathologic change be called the “arthropathy of fluorosis.”
The radiographic changes of this arthropathy of fluorosis include: cyst formation, sclerosis of subarticular cartilage, and narrowing of the joint space, similar to general degenerative arthropathy. But the calcification and ossification of tendons and ligaments around the joints, and of synovia and ligaments within the joints, arc characteristic changes of fluorosis and are rarely seen in degenerative arthropathy.