DISTRIBUTION OF MINERALIZATION INDEXES OF MODELING AND REMODELING OVER 8 MONTHS IN MIDDIAPHYSEAL GROSS SECTIONS OF FEMURS FROM ADULT SWINE

Background: This study assessed the distribution of active mineral for mation sites within the middiaphyseal femoral cross section of swine a nd determined the extent to which various subsections represented bone formation activity in the entire cross section, Methods: Twenty adult female swine (sows) were injected with two double (10-day intervals) labels 8 months apart, Labels involved fluorochrome markers of active mineral formation sites, Intact femoral middiaphyseal cross sections w ere embedded in polymethylmethacrylate, cut, and ground to 80 mu m for analysis, Each specimen was subdivided into 16 anatomical and eight g eometric subsections, Labeled mineralizing surface and mineral apposit ion rate were determined in the periosteal and endocortical envelopes, The number of labeled osteons per unit area of bone and osteonal mine ral apposition rate were determined in the intracortical envelope. Res ults: Periosteal mineralizing surface followed a bimodal distribution with highest surface activation on the anterior and posterior segments , Periosteal mineral apposition rate followed a modal distribution wit h highest apposition rates in the posterior portion of the cross secti on, The distribution of forming osteons was modal with highest frequen cies of labeled osteons in the posterior segment, No significant regio nal differences were detected for osteonal mineral apposition rate, en docortical mineralizing surface, or endocortical mineral apposition ra te, The location of either a single or a combination of two to four su bsections that best predicted mineralizing surface and mineral apposit ion rate in the entire cross section differed with each trait and enve lope, Fifty percent of the entire area as alternate anatomical subsect ions was required to predict >90% of variation in all traits evaluated , Overall, the predictability of mineralizing surface and mineral appo sition rate was similar for geometrically defined subsections, Conclus ion: At least 50% of the cross-sectional area from alternate anatomica l subsections must be measured to predict >90% of variation in periost eal, intracortical, and endocortical mineralizing surface and mineral apposition rate in the sow middiaphyseal femur. (C) 1998 Wiley-Liss, I nc.