Bone Vol. 19, No. 3, Supplement September 1996:1298-1693
Abstracts 151s The 7th International Congress of Bone Morphometry
89 BONE MODELING AND REMODELING IN THE SKELETON OF A SUPERNUMERARY DIGIT OF A CHILD AFFECTED BY SEGMENTAL GIGANTISM. F. Marotti Jr., C. Palumbo. M.F. Bertolani Dipartimento di Scienze Ginecologiche, Ostetriche e Pediatriche, Sezione di Pediatria and Dipartimento di Scienze Morfologiche e Medico Legali, Sezione di Anatomia umana, Modena (Italy)
The present paper deals with bone modeling and remodeling in a metatarsal bone of a 6th supernumerary digit in a 3-year-old child affected by Cutis Marrnorala Telangiectafica Congenita. The patient showed hypertrophy of the right thigh, leg and foot, and post-axial exadactylism of the right foot and hand. The metatarsal bone soon after surgical excision was fixed in 4% buffered paraformaldehyde for 3 hours and methylacrylate embedded. Ground sections (50pm thick), taken from various levels of the shaft, were microradiographed (Italstructures Microradiograph: 1.7 Kw, 18 mA). Analyses were performed by light microscope under transmitted and polarized light on unstained sections and their microradiographs. An intense apposition of primary woven bone was found on the periosteal surface of the supernumerary metatarsus, not accompanied by endosteal osteoclastic resorption, as usually occurs during normal bone modeling. As a consequence the shaft displayed an abnormous thick cortex and a relatively narrow medullary canal. Osteoclastic activity, not followed by bone formation, appeared to be particularly high inside the cortex; this led to the formation of several large resorption cavities, which gave the diaphysis a spongy architecture. Bone structure and mineralization appeared qualitatively normal. These observations show that both processes of bone modeling and bone remodeling took place in an abnormal manner in the supernumerary metatarsus. In bone modeling osteoblast activity is not paralleled by osteoclast resorption, whereas in bone remodeling osteoclastic resorption is not followed by osteon formation. Since the external size of the supernumerary metacarpus seems to exceed mechanical demand, owing to congenital abnormality, and considering that the phalanx in which it is contained likely is partially unloaded, the osteoporotic appearance of the coltex seems to depend on mechanical disuse rather than on congenital abnormality.
88 ULTRASTRUCTURAL EVIDENCE OF THE EXISTENCE OF A DENDRITIC NETWORK THROUGHOUT THE CELLS OF THE OSTEOGENIC LINEAGE: THE NOVEL CONCEPT OF WIRING- AND VOLUME-TRANSMISSION IN BONE. G. Marotti, S. Palazzini, C. Palumbo, M. Ferretti Dipartimento di Scienze Morfologiche e Medico Legali, Sezione di Anatomia umana, Universita di Modena (Italy)
TEM studies carried out in our laboratorv showed that the cells of the osteogenic lineage [stromal cells (SC), preosteoblasts (POB), osteoblasts (OB), osteocytes (OC), bone lining cells (BLC)] form a continuous protoplasmic network which extends from osteocytes to vascular endothelium. More precisely we found the following: 1) OC display an asymmetrical arborization, the dendrites from the vascular side in contact with OB or BLC being more numerous and far longer than those from the opposite side contacting OC; 2) the number of vascular dendrites in contact with OB are inversely proportional to the bone forming activity of the latter, and this finding leads us to postulate a inhibitory effect by OC upon OB which should occur, for instance, in the recruitment of the osteoblast-transformig osteocyte; 3) SC inside perivascular spaces have a stellate shape with long and slender cytoplasmic processes connecting the cells carpeting the bone surfaces (OB or BLC) with endothelial cells.
The occurrence of gap junctions among the cells of the osteogenic lineage, namely of junctions enabling metabolic and electric coupling, suggests the hypothesis that the activity of bone cells might be regulated not only by diffusion through the intercellular fluids of systemic (hormones) and local (cytokines, etc.) factors, but also by signals issued through the contacts of the osteogenic cell network. According to the terminology used for the central nervous system, the former corresponds to the volume transmission (VT) and the latter to the wiring tfansmission (WT). In the central nervous system, VT and WT have been shown to be highly complementary though functionally different. A similar situation we suggest might occur in bone, where VT likely represents the route of metabolic signals whereas WT the main pathway of mechanical stimuli.
A LONGITUDINAL EVALUATION OF TIME-RELATED BONE REMODELING AROUND FEMORAL IMPLANTS. K., T. Nishii , K. Nakata, M. Matsui Department of Orthopaedic Surgery, Osaka University Medical School, Osaka, (Japan)
Evaluation and prevention of periprosthetic resorptive changes after the total hip arthoplasties are of great imoortance for its longevityl. We evaluated bone remodeling following cementless total hip arthroplasy by dual-energy X-ray absorptiometry (DEXA) in a longitudinal fashion in twenty-one patients. After insertion of a fully porous-coated anatomical stem made of cobalt-chromium, bone mineral density (BMD) was analyzed at time intervals out until two years postoperatively. Bone remodeling was evaluated in terms of regional changes in BMD in the seven consecutive zones around the stem as well as the global change in BMD distribution over the whole oeriorosthetic area. The averaoed reoional BMD in all the seven zones showed a progressive de&ease:ranging from 10% to 26% of the BMD value at two weeks out to twelve months after the operation, and stabilized thereafter. The global change in the BMD distribution was expressed as two summarizing indices derived statistically by principal components analysis: the first index represents the change of average BMD over the whole periprosthetic area, and the second represents the severity of BMD decrease in the Proximal vs. distal areas. These two indices demonstrated similar patterns of time-related change for each patient in terms of regional BMD. The second index proved that proximally dominant bone remodeling differed greatly among the patients and appeared to be correlated significantly with the stem size and initial BMD in the distal oeriprosthetic area. The oresent study suggests that over the whole periprosthetic area, a large part of the bone remodeling process ceases after a relatively short period following surgery, and that stem size and the initial bone density in the distal portion are important considerations for early progressive remodeling. 1. Engh, C.A. et al.; JBJS, 74A(7): 1009-1020, 1992.
90 CORRELATION BETWEEN BONE MINERAL DENSITY (BMD) OF LUMBAR SPINE AND VERTEBRAL MORPHOMETRY. G.F. Mazzuoli. D. Diacinti, M. Acca, R. Rosso, E. DErasmo, S. Minisola Internal Medicine, University La Sapienza, Rome (Italy)
Aim of the study is to investigate the correlation between lumbar spine bone mineral density (LS-BMD) and the loss of height evaluated by means of the sum of anterior, middle and posterior vertebral body heights (AHs, MHs and PHs) from Tq to Ls by morphometry. 163 women (age 39-74 years), 76 premenopausal (age 39-54 years) and 87 postmenopausal (age 46-74 years) were studied. LS-BMD was measured by dual energy X-ray absorptiometry. AHs, MHs and PHs significantly correlate with LS-BMD; the correlation is higher when AHs (r = 0.81, p