Primary hyperparathyroidism: bone structure, balance, and remodeling before and 3 years after surgical treatment.

In 19 patients with primary hyperparathyroidism (PHPT) (14 women and 5 men; age 53 +/- 11 years, range 29-69 years), bone densitometry, biochemical markers of bone turnover, and iliac crest bone biopsies were obtained before and 3 years after successful surgical treatment. A significant increase in bone mineral content (BMC) was observed in both the lumbar spine (p < 0.001) and the proximal part of the distal forearm (p < 0.001), whereas the increase in BMC in the femoral neck was insignificant. Biochemical markers of bone formation (serum alkaline phosphatase, serum bone alkaline phosphatase and serum osteocalcin) and resorption (serum pyridinoline cross-linked telopeptide of type I collagen and urine N-telopeptide of type I collagen) all decreased following treatment. In cortical bone, relative cortical width increased following surgery (p < 0.05) and cortical porosity decreased (p < 0.01). No changes were observed in core width or cortical width. In cancellous bone, no significant changes were observed in any of the measured structural parameters. However, significant reductions in the extent of osteoid- (p < 0.01) and tetracycline-labeled surfaces (p < 0.001), and in bone formation rate (p < 0.001) and activation frequency (p < 0.001), were found. The numerical decrease in the extent of eroded surfaces did not reach significance (p = 0.057). No changes were observed in mineral appositional rate and adjusted appositional rate. The amount of bone resorbed (expressed as the resorption depth) and the amount of bone reformed (expressed as wall thickness) per remodeling cycle seemed unaffected by the treatment. Consequently, no effect on bone balance per remodeling cycle could be detected. The present study of PHPT patients showed that, within 3 years after surgery, BMC of both cancellous and cortical bone areas had increased. At the same time, bone turnover decreased markedly, as judged from biochemical as well as histomorphometric data, but no changes were seen in trabecular bone structure. In cortical bone, the relative cortical width increased and the cortical porosity decreased.

Three-dimensional reconstruction of entire vertebral bodies.

This paper describes a technique for 3-D reconstruction of large cancellous bone regions. The output is a 3-D array describing the original cancellous bone region, and the output can be used for any kind of measurement of the bone architecture. The technique was developed as a tool for researchers conducting experimental and clinical studies related to cancellous bone architecture and, ultimately, to cancellous bone quality. A set of new and unbiased methods for quantification of cancellous bone has been a stimulus for the development of the technique, as the quantification methods rely on 3-D information. The technique is based on automated serial sectioning, and all steps from specimen preparation to image segmentation are described in detail. Examples of 3-D reconstructed vertebral bodies are given. By use of the described technique, between 300 and 600 sections can be made and registered per hour, which means that an average vertebral body can be reconstructed in about 2 h. Compared to previous implementations of the general principle of serial sectioning, this is a significant improvement both in resolution and in time efficiency.

Marked changes in iliac crest bone structure in postmenopausal osteoporotic patients without any signs of disturbed bone remodeling or balance.

Successful iliac crest bone biopsies were obtained from 63 women with postmenopausal vertebral crush fracture osteoporosis. Structural and static histomorphometric parameters were compared with 25 age-matched normal females, who had suffered an unexpected and sudden death. The control group for dynamic parameters comprised 13 younger normal females. Marked structural changes were observed in the osteoporotic patients in cortical as well as cancellous bone. Cortical width, trabecular volume, trabecular bone surface density and trabecular number were all reduced, whereas trabecular separation and star volume were increased. On the other hand trabecular thickness was normal in the patients. These structural changes in cancellous bone indicate that extensive perforations of trabecular plates have occurred or that whole trabecular elements have been removed. The remodeling cycles of cancellous bone surface and the frequency by which they were repeated (activation frequency) did not differ significantly between osteoporotic patients and normal younger women. The bone balance per remodeling cycle in osteoporotic patients and controls was not significantly different. No subset of individuals in the group of osteoporotic patients could be identified regarding extent of resorptive and formative surfaces, bone formation rate or activation frequency. In the present osteoporotic patients nothing in the ongoing remodeling process could explain the marked changes in bone structure. The pathophysiological changes leading to osteoporosis may therefore occur earlier in life, maybe long before the manifestation of the disease.