Six months of disuse during hibernation does not increase intracortical porosity or decrease cortical bone geometry, strength, or mineralization in black bear (Ursus americanus) femurs

Meghan Elizabeth McGee Lawrence, Samantha J. Wojda, Lindsay N. Barlow, Thomas D. Drummer, Kevin Bunnell, Janene Auger, Hal L. Black, Seth W. Donahue

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Disuse typically uncouples bone formation from resorption, leading to bone loss which compromises bone mechanical properties and increases the risk of bone fracture. Previous studies suggest that bears can prevent bone loss during long periods of disuse (hibernation), but small sample sizes have limited the conclusions that can be drawn regarding the effects of hibernation on bone structure and strength in bears. Here we quantified the effects of hibernation on structural, mineral, and mechanical properties of black bear (Ursus americanus) cortical bone by studying femurs from large groups of male and female bears (with wide age ranges) killed during pre-hibernation (fall) and post-hibernation (spring) periods. Bone properties that are affected by body mass (e.g. bone geometrical properties) tended to be larger in male compared to female bears. There were no differences (p>0.226) in bone structure, mineral content, or mechanical properties between fall and spring bears. Bone geometrical properties differed by less than 5% and bone mechanical properties differed by less than 10% between fall and spring bears. Porosity (fall: 5.5±2.2%; spring: 4.8±1.6%) and ash fraction (fall: 0.694±0.011; spring: 0.696±0.010) also showed no change (p>0.304) between seasons. Statistical power was high (>72%) for these analyses. Furthermore, bone geometrical properties and ash fraction (a measure of mineral content) increased with age and porosity decreased with age. These results support the idea that bears possess a biological mechanism to prevent disuse and age-related osteoporoses.

Original languageEnglish (US)
Pages (from-to)1378-1383
Number of pages6
JournalJournal of Biomechanics
Volume42
Issue number10
DOIs
StatePublished - Jul 22 2009
Externally publishedYes

Fingerprint

Ursidae
Hibernation
Porosity
Femur
Bone
Bone and Bones
Geometry
Ashes
Minerals
Mechanical properties
Cortical Bone
Bone Fractures
Bone Resorption
Osteogenesis
Sample Size
Bone Density
Osteoporosis

Keywords

  • Black bear
  • Cortical bone
  • Disuse osteoporosis
  • Mechanical properties

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine
  • Biomedical Engineering
  • Rehabilitation

Cite this

Six months of disuse during hibernation does not increase intracortical porosity or decrease cortical bone geometry, strength, or mineralization in black bear (Ursus americanus) femurs. / McGee Lawrence, Meghan Elizabeth; Wojda, Samantha J.; Barlow, Lindsay N.; Drummer, Thomas D.; Bunnell, Kevin; Auger, Janene; Black, Hal L.; Donahue, Seth W.

In: Journal of Biomechanics, Vol. 42, No. 10, 22.07.2009, p. 1378-1383.

Research output: Contribution to journalArticle

McGee Lawrence, Meghan Elizabeth ; Wojda, Samantha J. ; Barlow, Lindsay N. ; Drummer, Thomas D. ; Bunnell, Kevin ; Auger, Janene ; Black, Hal L. ; Donahue, Seth W. / Six months of disuse during hibernation does not increase intracortical porosity or decrease cortical bone geometry, strength, or mineralization in black bear (Ursus americanus) femurs. In: Journal of Biomechanics. 2009 ; Vol. 42, No. 10. pp. 1378-1383.
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abstract = "Disuse typically uncouples bone formation from resorption, leading to bone loss which compromises bone mechanical properties and increases the risk of bone fracture. Previous studies suggest that bears can prevent bone loss during long periods of disuse (hibernation), but small sample sizes have limited the conclusions that can be drawn regarding the effects of hibernation on bone structure and strength in bears. Here we quantified the effects of hibernation on structural, mineral, and mechanical properties of black bear (Ursus americanus) cortical bone by studying femurs from large groups of male and female bears (with wide age ranges) killed during pre-hibernation (fall) and post-hibernation (spring) periods. Bone properties that are affected by body mass (e.g. bone geometrical properties) tended to be larger in male compared to female bears. There were no differences (p>0.226) in bone structure, mineral content, or mechanical properties between fall and spring bears. Bone geometrical properties differed by less than 5{\%} and bone mechanical properties differed by less than 10{\%} between fall and spring bears. Porosity (fall: 5.5±2.2{\%}; spring: 4.8±1.6{\%}) and ash fraction (fall: 0.694±0.011; spring: 0.696±0.010) also showed no change (p>0.304) between seasons. Statistical power was high (>72{\%}) for these analyses. Furthermore, bone geometrical properties and ash fraction (a measure of mineral content) increased with age and porosity decreased with age. These results support the idea that bears possess a biological mechanism to prevent disuse and age-related osteoporoses.",
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AU - Barlow, Lindsay N.

AU - Drummer, Thomas D.

AU - Bunnell, Kevin

AU - Auger, Janene

AU - Black, Hal L.

AU - Donahue, Seth W.

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