VOLUME-REFERENT BONE TURNOVER ESTIMATED FROM THE INTERLABEL AREA FRACTION AFTER SEQUENTIAL LABELING

In the compact bony otic capsule remodeling is low, and bone remodelin g units are distributed centrifugally in relation to inner ear tissues and spaces. Fluorochrome-labeled bone remodeling units are scarce, ab ortive, and tortuous with no uniform direction of movement. This study presents a method for the estimation of volume-referent bone turnover based on measurements of the fractional area between labels after seq uential labeling with osteofluorochromes. The applicability of this me thod is tested against a classical quantification method in undecalcif ied cortical specimens from the canine humerus, where both methods can be used. The estimate of bone turnover derived from the new sequentia l labeling in eight dogs is 7.4% (SER 2.1%) per year and the classic e stimate derived from calculations of the formative osteonal area and t he formative period yields 6.9% (SEM 2.1%) per year. Agreement is suff icient to justify future measurements of absolute bone turnover in seq uentially labeled perilabyrinthine bone. (C) 1998 by Elsevier Science Inc. All rights reserved.