The effects of antifracture therapies on the components of bone strength: assessment of fracture risk today and in the future.
OBJECTIVE
To summarize the current knowledge regarding the impact of the most common antifracture medications on the various determinants of bone strength.


METHODS
Relevant English-language articles acquired from Medline from 1966 to January 2005 were reviewed. Searches included the keywords bone AND 1 of the following: strength, remodeling, microcrack, structure, mineralization, collagen, organic, crystallinity, osteocyte, porosity, diameter, anisotropy, stress risers, or connectivity AND alendronate, estrogen, etidronate, hormone replacement therapy, parathyroid hormone, risedronate, OR teriparatide. Abstracts from relevant conference proceedings were also reviewed for pertinent information.


RESULTS
Antiresorptive therapies increase bone strength through decreasing bone turnover. This lower bone turnover results in a higher mean mineralization and decreases the number of active resorption pits within bone at any given time. These resorption pits are speculated to be areas of focal weakness and a higher number of them would, if all other things were equal, result in greater fragility. Parathyroid hormone therapy increases the rate of bone remodeling, which introduces many resorption pits, but this source of strength loss is thought to be compensated by rapid increases in bone mass.


CONCLUSIONS
Both the antiresorptives, particularly bisphosphonates, and the parathyroid hormone therapy increase bone strength; however, the changes that are elicited to achieve this differ significantly.
Davison
K Shawn
KS
Clinical Research Scientist, Department of Medicine, Laval University, Sainte Foy, Quebec, Canada. ebmedicine@gmail.com
Siminoski
Kerry
K
Adachi
J D
JD
Hanley
David A
DA
Goltzman
David
D
Hodsman
Anthony B
AB
Josse
Robert
R
Kaiser
Stephanie
S
Olszynski
Wojciech P
WP
Papaioannou
Alexandra
A
Ste-Marie
Louis-George
LG
Kendler
David L
DL
Tenenhouse
Alan
A
Brown
Jacques P
JP
D015519:Bone Density / Q000187:drug effects*; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D016723:Bone Remodeling / Q000502:physiology*; D001842:Bone and Bones / Q000187:drug effects / Q000293:injuries*; D002113:Calcification, Physiologic / Q000502:physiology*; D005598:Fractures, Spontaneous / Q000517:prevention & control*; D006801:Humans; D012307:Risk Factors
D050071:Bone Density Conservation Agents