Black bear femoral geometry and cortical porosity are not adversely affected by ageing despite annual periods of disuse (hibernation)

Meghan E. McGee, Danielle L. Miller, Janene Auger, Hal L. Black, Seth W. Donahue

Research output: Contribution to journalArticle

11 Scopus citations


Disuse (i.e. inactivity) causes bone loss, and a recovery period that is 2-3 times longer than the inactive period is usually required to recover lost bone. However, black bears experience annual disuse (hibernation) and remobilization periods that are approximately equal in length, yet bears maintain or increase cortical bone material properties and whole bone mechanical properties with age. In this study, we investigated the architectural properties of bear femurs to determine whether cortical structure is preserved with age in bears. We showed that cross-sectional geometric properties increase with age, but porosity and resorption cavity density do not change with age in skeletally immature male and female bears. These findings suggest that structural properties substantially contribute to increasing whole bone strength with age in bears, particularly during skeletal maturation. Porosity was not different between skeletally immature and mature bears, and showed minimal regional variations between anatomical quadrants and radial positions that were similar in pattern and magnitude between skeletally immature and mature bears. We also found gender dimorphisms in bear cortical bone properties: females have smaller, less porous bones than males. Our results provide further support for the idea that black bears possess a biological mechanism to prevent disuse osteoporosis.

Original languageEnglish (US)
Pages (from-to)160-169
Number of pages10
JournalJournal of Anatomy
Issue number2
Publication statusPublished - Feb 1 2007
Externally publishedYes



  • Ageing
  • Black bear
  • Cortical bone
  • Disuse osteoporosis
  • Porosity

ASJC Scopus subject areas

  • Anatomy
  • Histology
  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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