An automated analysis of intracortical porosity in human femoral bone across age

The matrix of human cortical bone is arranged around a network of vascular spaces (hereafter referred to as "pores"). Our aim was to investigate age-r elated differences in human cortical porosity (total pore area divided by c ortical bone area), pore size and number, and surface to volume ratios, whi le adjusting for sex, height, and weight, Ninety-six specimens of entire tr ansverse sections of human femoral diaphysis, from subjects aged 21-92 year s, were examined. We used our established automated image acquisition and a nalysis stem which measures pores from entire sections of multiple specimen s of bone, Over 400,000 pores were recorded. Results showed a greater poros ity in older bone (p < 0.01) but marked variation in porosity for any given age, The cohort median, of the specimen medians, of pore cross-sectional a rea was 2050 mu m(2) Older specimens did not have more pores than younger s pecimens but had a greater proportion of larger pores (p < 0.05) and greate r intraspecimen variation in pore size (p < 0.001). The pore surface to bon e matrix volume ratio was a median 2.3 mm(2)/mm(3). This varied more than 4 -fold between individuals but did not relate to age. No simple relationship s were found between any of the measured parameters and either sex, height, or weight, even after adjustment for age. We conclude that the greater por osity in older specimens is due to greater pore size rather than a larger n umber of pores. Age, however, explains little of the inter-individual varia tion in the parameters studied.