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Quantification of ovine bone adaptation to altered load: morphometry, density, and surface strain
1Department of Anatomy, Royal College of Surgeons in Ireland, Dublin, Ireland. tclee@rcsi.ie
European Journal of Morphology
|October 18, 2005
Summary
Bone adapts to altered mechanical loading through a process that utilizes and refines initial responses. Increased loading led to sustained bone growth and reduced strain, demonstrating intelligent and accurate adaptation.
Area of Science:
- Orthopedic biomechanics
- Bone adaptation
- Skeletal remodeling
Background:
- Mechanical loading is crucial for bone health and adaptation.
- Understanding bone's response to altered loading is key for orthopedic interventions.
Purpose of the Study:
- To investigate bone's adaptive response to increased and decreased mechanical loading in vivo.
- To differentiate between adaptive bone remodeling and the regional acceleratory phenomenon (RAP).
Main Methods:
- Sheep proximal radius model with ulnar osteotomy (increased load) or Steinmann pinning (decreased load).
- Intravenous fluochromes for bone formation labeling.
- In vitro surface strain measurements.
- Analysis of cross-sectional area (CSA) and bone density up to 24 weeks.
Main Results:
- Increased loading (Group O) led to sustained CSA increase and bone density, reducing surface strain.
- Decreased loading (Group P) resulted in initial RAP, followed by bone resorption and reduced CSA below controls.
- Bone adaptation in Group O was intelligent and accurate, utilizing RAP and achieving near-normal strain levels.
Conclusions:
- Bone exhibits an 'intelligent' and accurate adaptive response to altered mechanical loading.
- The adaptive response can be distinguished from the non-specific RAP caused by surgical trauma.
- Sustained adaptation in response to increased load optimizes bone structure to reduce surface strain.