Development of a fluorescent light technique for evaluating microdamage in bone subjected to fatigue loading

Sarandeep S. Huja, M. Sayeed Hasan, Ramana Pidaparti, Charles H. Turner, Lawrence P. Garetto, David B. Burr

Research output: Contribution to journalArticle

40 Scopus citations


A new method using fluorescent light microscopy has been developed to visualize and evaluate bone microdamage. We report the findings of two different experiments with a common aim of comparing the fluorescent light technique to the brightfield method for quantifying microdamage in bone. In Experiment 1, 36 canine femurs were tested in four-point cyclic bending until they had lost between 5 and 43% of their stiffness. The loaded portion of the bone was stained en bloc with basic fuchsin for the presence of damage. Standard point counting techniques were used to calculate fractional damaged area (Dm.Ar=Cr.Ar/B.Ar, mm2/mm2) under brightfield and fluorescent microscopy. In Experiment 2, bone microdamage adjacent to endosseous implants, subjected to fatigue loading (150,000 cycles, 2Hz and 37°C) ex vivo was examined. The bone around the implant was either allowed to heal (adapted specimen) for 12 weeks after placement in dog mid-femoral diaphyses prior to testing or was loaded immediately to simulate non-healed bone surrounding endosseous implants (non-adapted). Crack numerical density (Cr.Dn=Cr.N/B.Ar, #/mm2), crack surface density (Cr.S.Dn=Tt.Cr.Le/B.Ar, mm/mm2) and fractional damaged area were calculated separately by both techniques in the adapted and non-adapted specimens. In both Experiments 1 and 2, significantly more microdamage was detected by the fluorescent technique than by the brightfield method. Also, there was a trend towards higher intraobserver repeatability when using the fluorescent method. These results suggest that the brightfield technique underestimates microdamage accumulation and that the fluorescent technique better represents the actual amounts of microdamage present. The results demonstrate that the fluorescent method provides an accurate and precise approach for bone microdamage evaluation, and that it improves the prediction of stiffness loss from damage accumulation. Copyright (C) 1999 Elsevier Science Ltd.

Original languageEnglish (US)
Pages (from-to)1243-1249
Number of pages7
JournalJournal of Biomechanics
Issue number11
StatePublished - Nov 1 1999


  • Bone
  • Endosseous implant
  • Fatigue
  • Histomorphometry
  • Microdamage

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

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