UNBIASED ESTIMATION OF VERTEBRAL TRABECULAR CONNECTIVITY IN CALCIUM-RESTRICTED OVARIECTOMIZED MINIPIGS

The topological changes in vertebral cancellous bone were estimated in vertebrae from calcium-restricted ovariectomized Sinclair S-l minipig s, a recently described animal model of cancellous osteopenia, Connect ivity was estimated using unbiased stereological principles in disecto r pairs of sections from the first lumbar vertebrae, Connectivity dens ity was increased approximately twofold when compared with sham-operat ed minipigs fed a standard diet, These alterations in topology occurre d coincident with a 25% increase in final resorption depth and a 150% increase in vertebral marrow star volume, Taken together, these change s suggest that in calcium-restricted ovariectomized minipigs, trabecul ar plates are transformed into rods by perforation, These changes in t opology appear to be due, at least in part, to excessive resorptive ce ll function at the level of the bone remodeling unit, Conventional two -dimensional estimators of structural parameters of cancellous bone we re not only less sensitive to these changes in topology but, in some c ases, the estimates were directionally reversed.