Hyperphosphatemic Tumoral Calcinosis after Total Knee Arthroplasty

We report a case of hyperphosphatemic tumoral calcinosis (TC) that occurred after total knee arthroplasty. A 64-year-old Japanese man presented with painful swellings in both shoulders, the left elbow, and the right hip that developed after he underwent total knee arthroplasty (TKA). The pathology of the patient’s bone at the time of TKA included a thick osteoid seam with calcareous deposition at the margin of the trabecular bone, which is not generally seen in osteoarthritis. Computed tomography scans of the swollen joints demonstrated leaflet and amorphous calcification masses around the joints. We diagnosed the patient with TC. The present case highlights that TC lesions are rare but should be considered in the differential diagnosis of subcutaneous soft and hard masses around the joint.

Effect of testosterone on bone mineralization of the hypophosphataemic rat

Clinical observations in patients with X-linked hypophosphataemic rickets, that bone changes can be corrected during puberty, suggest that androgen can participate actively in the process of bone mineralization. In the present study we investigated the role of testosterone on the bone mineralization of male rats placed on a low phosphorus and vitamin D diet and kept in complete darkness after weaning. After 1 5 days the animals presented hypophosphataemia, rickets and osteomalacia, as assessed by histomorphometry of the tibia and seventh caudal vertebra calcification fronts respectively. Testosterone propionate administration for five days, while the animals were kept on the same rachitogenic diet, induced an improvement in the bone mineralization process of the hypophosphataemic rat independently of serum phosphate levels. Testosterone-treated rats were cured of rickets but not of osteomalacia, despite the reduction in osteoid seam area.

Calcitriol corrects bone loss induced by oophorectomy in rats

The effects of calcitriol on histomorphometric parameters of bone structure, formation, and resorption were evaluated in 21 normal or oophorectomized rats. Twelve rats were oophorectomized; six of these received daily subcutaneous injections of 135 pmol of calcitriol for 14 wk starting 38 wk after oophorectomy. Nine rats were sham operated; five of these received the same treatment with calcitriol. There were no differences in serum calcium and phosphorus between sham-operated and oophorectomized animals and rats with or without calcitriol. Calcitriol treatment of sham-operated rats produced an increase in cancellous and cortical bone mass. Oophorectomy resulted in decreased cancellous and cortical bone mass and in a decreased ratio between mineralized and nonmineralized bone. There was no difference in bone-osteoclast interface and osteoid seam width among all groups of rats. Calcitriol corrected, at least in part, the bone loss in oophorectomized animals, normalized the ratio between mineralized and nonmineralized bone, and restored mean growth plate width to normal.

Effects of long-term infusion of physiologic doses of 1-34 PTH on bone

It has been suggested that small doses of PTH could exert an anabolic effect on bone and could be beneficial in the management of bone diseases secondary to low bone formation. The effects of 20 wk of continuous infusion of 0.05 U.kg-1.h-1 of 1-34 PTH on cellular, structural, and dynamic parameters of bone were studied in inbred beagles. This physiologic or near physiologic dose of PTH caused a small but significant rise in the concentration of serum calcium and a significant increment in the plasma concentration of 1,25(OH)2D. In addition, the sustained infusion of PTH was associated with a significant increment in volume and surface density of osteoid without a change in bone mass. Mineralization of osteoid was not altered, as evidenced by normal double tetracycline uptake and normal osteoid seam thickness. The enhanced osteoid production was not due to augmented bone formation by individual osteoblasts or basic remodeling units but rather to increased activation frequency resulting in an increased number of remodeling units. There was also augmented bone resorption at the tissue level. The data indicate that small doses of PTH do not have an anabolic effect on the skeleton because they are not associated with increased net bone formation. Rather, PTH administration is associated with an increase in coupled bone turnover.

Tissue-level bone formation rates in chronic renal failure, measured by means of tetracycline bone labeling

In 16 patients entering a renal dialysis program and given tetracycline bone labels prior to 11th rib biopsy, tissue-level bone formation rates measured by quantitive histological analysis fell below normal in each case and on both the haversian and cortical–endosteal bone surfaces, averaging one-third of normal. On both envelopes there were increases in the relative and absolute amounts of osteoid seam perimeter in a unit amount of bone as well as in the total volume of osteoid in a unit amount of bone.

NUMBER OF OSTEOBLASTS PER UNIT AREA OF OSTEOID SEAM IN CORTICAL HUMAN BONE

The fifth, sixth, or seventh ribs from 97 metabolically normal people of all ages were examined. Mineralized longitudinal sections were specially stained to show both osteoid seams and osteoblasts. In 19 persons, the mean number of osteoblasts per mm2 of active osteoid seam surface on 111 seams was 4500. In 66 persons, a layer of osteoblasts was present on only 29% of 121 seams. The seams without layers of osteoblasts nevertheless were part of actively forming Haversian systems as judged by other criteria. No significant age differences were observed in either value.