Faculty Bibliography

STUDY DESIGN: Radiographic and direct quantitative measurements were made of the cortical and the trabecular anatomy of the sacrum. OBJECTIVES: To define the trabecular patterns and the cortical thickness of the sacrum. SUMMARY OF BACKGROUND DATA: The sacrum is a frequent site of internal fixation. In previous anatomic studies, investigators have focused on specific dimensional measurements of the sacrum, whereas others have described the anatomic course of the anterior sacral neurovascular or visceral structures. Computed tomographic imaging also has been used to quantify the sacral trabecular bone density. The internal architecture of the sacrum has yet to be described in detail. METHODS: Seventeen cadaveric sacra were studied by computed tomographic imaging and then were sectioned at 3-mm intervals in the axial or sagittal plane. The cortical thickness of each section was measured under microscopic visualization. The sections were radiographed with high-resolution imaging to delineate their trabecular patterns. RESULTS: The trabecular bone was densest adjacent to the endplates. The sacral body trabeculae were arranged in a cruciate pattern, and bony atrophy occurred in a systematic fashion. An alar void was a consistent finding in all specimens with definable boundaries. The cortical thickness was uniform throughout the surface of each specimen. The computed tomographic images correlated with the anatomy observed in the cadaveric sections. CONCLUSION: The internal bony architecture of the sacrum has several consistent features. The relatively uniform cortical thickness seen in each sacral specimen may have clinical significance in the internal fixation of this region

Parathyroid hormone (PTH), osteocalcin and alkaline phosphatase (AP) were investigated before and after parathyroidectomy in 12 patients receiving hemodialysis. Early post-parathyroidectomy, PTH decreased (p less than 0.001), AP increased (p less than 0.05), but osteocalcin remained unchanged. At 3 months, osteocalcin and AP declined. A negative correlation was observed between aluminum staining and post-parathyroidectomy osteocalcin. In conclusion, early post-parathyroidectomy, osteocalcin and AP reflect persistent osteoblastic activity, which declined after 3 months. In patients receiving hemodialysis both variables may represent different aspects of osteoblastic activity and osteocalcin allows mixed uremic osteodystrophy after parathyroidectomy

Selenium is involved in several important biochemical pathways relevant to rheumatic diseases. Experimental and clinical studies suggest that selenium modulates the inflammatory and immune responses. Patients suffering from inflammatory rheumatic diseases often have low selenium levels, but this finding does not correlate with disease severity. Selenium supplementation needs stricter selection criteria and better ascertainment of dose to obtain a stimulatory or inhibitory effect relevant to the disease state. Prevention of marginal selenium deficiency by moderate supplementation might enhance host defense mechanisms