Open AccessCement lines of secondary osteons in human bone are not mineral‐deficient: New data in a historical perspective
Author(s) -
Skedros John G.,
Holmes Jennifer L.,
Vajda Eric G.,
Bloebaum Roy D.
Publication year - 2005
Publication title -
the anatomical record part a: discoveries in molecular, cellular, and evolutionary biology
Language(s) - English
Resource type - Journals
eISSN - 1552-4892
pISSN - 1552-4884
DOI - 10.1002/ar.a.20214
Subject(s) - cement , scanning electron microscope , materials science , polymethyl methacrylate , bone cement , electron microscope , energy dispersive x ray spectroscopy , mineralogy , composite material , biomedical engineering , biophysics , chemistry , optics , biology , medicine , physics , polymer
Using qualitative backscattered electron (BSE) imaging and quantitative energy dispersive X‐ray (EDX) spectroscopy, some investigators have concluded that cement (reversal) lines located at the periphery of secondary osteons are poorly mineralized viscous interfaces with respect to surrounding bone. This conclusion contradicts historical observations of apparent highly mineralized (or collagen‐deficient) cement lines in microradiographs. Such conclusions, however, may stem from unrecognized artifacts that can occur during scanning electron microscopy. These include specimen degradation due to high‐energy beams and the sampling of electron interaction volumes that extend beyond target locations during EDX analysis. This study used quantitative BSE imaging and EDX analysis, each with relatively lower‐energy beams, to test the hypothesis that cement lines are poorly mineralized. Undemineralized adult human femoral diaphyses (n = 8) and radial diaphyses (n = 5) were sectioned transversely, embedded in polymethyl methacrylate, and imaged in a scanning electron microscope for BSE and EDX analyses. Unembedded samples were also evaluated. Additional thin embedded samples were stained and evaluated with light microscopy and correlated BSE imaging. BSE analyses showed the consistent presence of a bright line (higher atomic number) coincident with the classical location and description of the cement line. This may represent relative hypermineralization or, alternatively, collagen deficiency with respect to surrounding bone. EDX analyses of cement lines showed either higher Ca content or equivalent Ca content when compared to distant osteonal and interstitial bone. These data reject the hypothesis that cement lines of secondary osteons are poorly mineralized. © 2005 Wiley‐Liss, Inc.